Patent Publication Number: US-11639806-B2

Title: Thermostat control using touch sensor gesture based input

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/005,666, entitled “Thermostat Control Using Touch Sensor Gesture Based Input,” filed Aug. 28, 2020, which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     A thermostat is used to control the operation of a heating system, cooling system, or both. Users can benefit from using a smart thermostat that can communicate via a wireless network with a cloud-based server. Such wireless network connectivity can allow for the thermostat to be controlled remotely by a user, such as via an application executed on a user&#39;s mobile device. The more straightforward and easy to interact with a smart thermostat is, the more likely users will desire to interact with the smart thermostat and take advantage of its features. 
     SUMMARY 
     Various methods and systems for smart thermostats are presented herein. A smart thermostat can include a thermostat housing defining a rounded front aperture and having a sidewall. A smart thermostat can include a wireless network interface housed by the thermostat housing. A smart thermostat can include a capacitive touch strip, housed by the thermostat housing, that senses a plurality of gestures. The capacitive touch strip can be positioned within the thermostat housing such that the plurality of gestures sensed by the capacitive touch strip are performed on an arc of an external surface of the sidewall. A smart thermostat can include an electronic display, housed by the thermostat housing, such that the electronic display is visible in the front rounded aperture of the thermostat housing. A smart thermostat can include a processing system, comprising one or more processors, housed by the thermostat housing, that is in communication with the wireless network interface, the capacitive touch strip, and the electronic display. The processing system can be configured to cause the electronic display to display a plurality of icons arranged in a graphical arc. 
     Embodiments of a smart thermostat may have one or more of the following features: A smart thermostat can include a reflective cover positioned within the rounded front aperture of the thermostat housing such that the electronic display is viewed through the reflective cover. The reflective cover can have a reflectivity sufficient to produce a mirrored effect when viewed and a transmissivity sufficient to allow illuminated portions of the electronic display to be visible when viewed through the reflective cover. The reflective cover can be continuous over an entirety of the rounded front aperture such that no gaps, holes, lens, or other discontinuities are present within the reflective cover. The electronic display might not a touch screen and no user interface component of the smart thermostat has a moving part. The arc on the external surface of the sidewall can extend continuously from a starting angle to an ending angle. The plurality of icons arranged in the graphic arc may be between the starting angle and the ending angle. The plurality of gestures can include a tap gesture and a swipe gesture. An icon of the plurality of icons may be selected using the tap gesture. Switching selection among the plurality of icons can be performed using the swipe gesture. A smart thermostat can include a radar sensor, housed by the thermostat housing, that detects occupancy within an environment of the smart thermostat through the reflective cover positioned within the rounded front aperture of the thermostat housing by emitting electromagnetic radiation and receiving reflected electromagnetic radiation. A smart thermostat can include an ambient light sensor, housed by the thermostat housing, that detects an ambient lighting level through the reflective cover positioned within the rounded front aperture of the thermostat housing. The ambient light sensor may be in communication with the processing system. The processing system can be further configured to control a brightness of the electronic display at least partially based on information from the ambient light sensor. The reflective cover can be continuous over an entirety of the rounded front aperture such that no gaps, holes, lenses, or other discontinuities are present within the reflective cover. The reflective cover can include a ceramic oxide layer and does not include any metallic layers. The capacitive touch strip can include a plurality of electrodes. The plurality of electrodes can include at least six electrodes. Each electrode of the plurality of electrodes can be shaped such that a multi-segment border with an adjacent electrode of the plurality of electrodes is present to increase a likelihood that a finger is sensed by multiple electrodes of the plurality of electrodes. The radar sensor can be positioned approximately a distance equal to an odd multiple of a quarter wavelength of the emitted electromagnetic radiation to decrease constructive interference. The radar sensor may emit frequency-modulated continuous wave (FMCW) radar, comprising a plurality of chirps. The processing system may be further configured to select information to present on the electronic display based on a distance to a person detected using the FMCW radar. 
     A smart thermostat can include a backplate, comprising a plurality of wire terminals configured to receive wires that are connected with a heating, ventilation, and cooling (HVAC) system. The backplate can removably attached with the thermostat housing. 
     In some embodiments, a method for interacting with a smart thermostat is presented. The method can include emitting, by a radar sensor of the smart thermostat, radio waves through a reflective cover of the smart thermostat. The reflective cover may be positioned within a rounded front aperture of a thermostat housing of the smart thermostat. The reflective cover may have a reflectivity sufficient to produce a mirrored effect when viewed and a transmissivity sufficient to allow illuminated portions of an electronic display of the smart thermostat to be visible when viewed through the reflective cover. The method can include receiving, by the radar sensor, reflected radio waves through the reflective cover of the smart thermostat. The method can include determining, by the smart thermostat, based on the reflected radio waves, that a user is present in a vicinity of the smart thermostat. The method can include activating an electronic display of the smart thermostat in response to determining that the user is present in the vicinity of the smart thermostat, such that a user interface is visible through the reflective cover. 
     Embodiments of such a method can include one or more of the following features: The reflective cover may have a transmissivity between 25% and 55%. The method can include displaying, by the electronic display, a plurality of icons arranged in a graphical arc. A capacitive touch strip may be positioned within the thermostat housing such that a plurality of gestures sensed by the capacitive touch strip are performed on an arc of an external surface of a sidewall of the thermostat housing. The arc on the external surface of the sidewall can extend continuously from a starting angle to an ending angle. The plurality of icons can be arranged in the graphic arc are between the starting angle and the ending angle. The method can include receiving user input via the capacitive touch strip, wherein the user input is selected from the plurality of gestures that comprises a tap gesture and a swipe gesture. The icon of the plurality of icons is selected using the tap gesture and switching selection among the plurality of icons is performed using the swipe gesture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A further understanding of the nature and advantages of various embodiments may be realized by reference to the following figures. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
         FIG.  1    illustrates an embodiment of a smart thermostat with an electronic display presenting information. 
         FIG.  2    illustrates an embodiment of a user&#39;s hand being present near thermostat that is mounted to a wall. 
         FIG.  3 A  illustrates an embodiment of a smart thermostat as viewed from the front. 
         FIG.  3 B  illustrates an embodiment of a smart thermostat as viewed from the right. 
         FIG.  4 A  illustrates an embodiment of a layer stack of a reflective cover. 
         FIG.  4 B  illustrates another embodiment of a layer stack of a reflective cover. 
         FIG.  5    illustrates an embodiment of a thermostat mounting system. 
         FIG.  6    illustrates an embodiment of a smart thermostat system. 
         FIG.  7    illustrates an embodiment of a default user interface that may be presented by thermostat. 
         FIG.  8    illustrates an embodiment of a default user interface that may be presented by thermostat. 
         FIG.  9    illustrates an embodiment of a thermostat presenting a default user interface that may be presented when heating is active while a dual heating-cooling mode is enabled. 
         FIG.  10    illustrates an embodiment of a thermostat presenting a main menu. 
         FIG.  11    illustrates an embodiment of a thermostat presenting a main menu on which a warning is present. 
         FIG.  12    illustrates an embodiment of a thermostat presenting a heating/cooling menu. 
         FIG.  13    illustrates an embodiment of thermostat in which a more items available icon is present on a menu. 
         FIG.  14    illustrates a top view of an embodiment of a thermostat using radar to sense for a user in an ambient environment of the thermostat. 
         FIG.  15    illustrates an embodiment of a thermostat with its cover removed. 
         FIG.  16    illustrates a chirp timing diagram for frequency-modulated continuous wave (FMCW) radar radio waves output by a radar sensor. 
         FIG.  17    illustrates an embodiment of a radar sensor that may be used by a thermostat. 
         FIG.  18    illustrates an embodiment of a touch strip. 
         FIG.  19    illustrates an embodiment of a touch strip flexed in an arc for mounting to an interior surface of a thermostat housing. 
         FIG.  20    illustrates an embodiment of a method for interacting with a smart thermostat. 
     
    
    
     DETAILED DESCRIPTION 
     A smart thermostat refers to a thermostat that can communicate via a network and allows a user to interact with the smart thermostat from a remote location, such as via a mobile device (e.g., smartphone, tablet computer, desktop computer, laptop computer, etc.). Additionally or alternatively, a smart thermostat has advanced features such as sensing as to whether any persons are in the vicinity of the smart thermostat and adjusting a setpoint temperature of the thermostat based on the sensed occupancy. 
     When a smart thermostat is installed, such as in a user&#39;s home, the user may desire that the smart thermostat be relatively easy to interact with and is also aesthetically pleasing. Embodiments detailed herein are directed to smart thermostats that can include a touch strip that is used by the user to provide input directly to the smart thermostat. In some embodiments, the touch strip is the only user interface present on the smart thermostat. Additionally, the user can interact with the thermostat via an application executed on a mobile device. 
     The smart thermostat may have a mirrored cover on a face of the thermostat. When the electronic display is turned off, the mirrored cover may have the visual effect of appearing to be a mirror to a user viewing the face of the thermostat. When the electronic display is illuminated, the mirrored cover has a sufficient transmissivity to allow the illuminated portion of the electronic display to be viewed by the user through the cover. In some embodiments, the cover does not have any cutouts, holes, lenses, or variations on the front surface that could be visible to the user. 
     The smart thermostat may have a radar sensor. The radar sensor may sense the ambient environment of the smart thermostat through the cover. The cover may use one or more ceramic oxide layers to achieve reflectivity rather than using any metallic layers. In some embodiments, no metallic layer is present within the cover. The lack of a metallic layer can help increase the transmissivity for electromagnetic radiation (or radio waves) emitted by the radar sensor and received by the radar sensor through the cover. 
     Further detail regarding the smart thermostat is provided in relation to the figures.  FIG.  1    illustrates an embodiment of a smart thermostat  100  with an electronic display presenting information. As visible in  FIG.  1   , housing  110 , cover  120 , and a portion of an illuminated electronic display  130  (“display  130 ”) can be seen. 
     Housing  110  defines rounded aperture  112 , such as a circular aperture, in which cover  120  may be attached with housing  110 . Housing  110  includes sidewall  111 . In the illustrated embodiment, sidewall  111  is generally cylindrical. Around an axis perpendicular to cover  120 , a radius of sidewall  111  may be greater at front of housing  110  where cover  120  is housed and smaller toward a back of housing  110 . 
     Cover  120  is housed by housing  110  such that within aperture  112  cover  120  is visible when the front of smart thermostat  100  is viewed. Cover  120  can have a reflectivity such that when display  130  is not illuminated, cover  120  appears to be a mirror when viewed by a user. 
     Display  130  is housed behind cover  120  such that, when illuminated, the portion of display  130  that is illuminated is visible through cover  120  by a user. In some embodiments, due to the reflectivity of cover  120 , an edge of display  130  is not visible to a user regardless of whether display  130  is illuminated, partially illuminated, or not illuminated. Therefore, the overall effect experienced by a user may be that cover  120  appears as a mirror and portions of display  130 , when illuminated, are visible through cover  120 . 
     In some embodiments, display  130  is not a touch screen. Therefore, in such embodiments, a user is required to use another user interface to interact with smart thermostat  100 . The user may use an application executed by a mobile device to interact with the thermostat via a wireless network or a direct wireless connection (e.g., Bluetooth). A user interface, such as a capacitive touch strip, may be present on smart thermostat  100 . In some embodiments, the capacitive touch strip is the only user interface present on smart thermostat through which a user can interact with presented menus, icons, and other data presented on display  130 . Further, in some embodiments, no user interface present on smart thermostat  100  has any moving parts. When smart thermostat  100  is fully installed, no components may be accessible or visible to the user that are movable. 
       FIG.  2    illustrates an embodiment  200  of a user&#39;s hand being present near thermostat  100  that is mounted to wall  201 . In embodiment  200 , cover  120  is sufficiently reflective that a reflection  220  of user&#39;s hand  210  is visible. Cover  120  has a sufficient transmissivity that temperature  230 , as presented by display  130  through cover  120 , is also visible. To calculate transmittance, a perception weighted average can be used. In some embodiments, such as those in which cover  120  appears to have a “silver” tint, transmissivity may be 29%. For other colors, such as when cover  120  has a “rose” or “nickel” tint, transmissivity may be 22% and 18.6% respectively. In other embodiments, transmissivity may be between 15% and 55%. Reflectivity may be between 75% and 40% depending on embodiment. 
     As can be seen in embodiment  200 , except for portions of display  130  that are illuminated, cover  120  appears as an uninterrupted surface with no gaps, holes, lens, or other discontinuities present on cover  120 . 
       FIG.  3 A  illustrates an embodiment of a smart thermostat  300  as viewed from the front. When mounted on a wall or other surface, cover  120  is opposite the portion of thermostat  300  that mounts to the wall or other surface. Therefore, when a user is facing mounted thermostat  300 , cover  120  is visible. 
     Smart thermostat  300  can represent an embodiment of thermostat  100  of  FIGS.  1  and  2   . Housing  110  can define a rounded aperture in which cover  120  is located. In some embodiments, housing  110  defines a circular aperture in which cover  120  is located. In such embodiments, cover  120  can be circular. As previously detailed, cover  120  can form an uninterrupted surface with no gaps, holes, lens, or other discontinuities present on cover  120 . Cover  120  has sufficient transmissivity to allow light emitted by electronic display  130  located within housing  110  to be visible through cover  120 . Cover  120  can have sufficient reflectivity such that a mirrored effect is present on portions of cover  120  that are not currently being illuminated from behind by electronic display  130 . Notably, in some embodiments, it is not possible for a user to view where an edge of electronic display  130  is through cover  120  due to the reflectivity of cover  120 . 
       FIG.  3 B  illustrates an embodiment of a smart thermostat  300  as viewed from the right. Thermostat  300  can represent thermostat  100  of  FIG.  1   . When thermostat  300  is mounted to a wall or other surface, touch strip indicator  310  may be visible on the right side of sidewall  111 . Touch strip indicator  310  may be a visible indicator, such as a line, shading, or some form of shape or marking that serves as a visible indicator as to where a user can touch sidewall  111  to provide user input. Within housing  110 , on an inner side of the sidewall opposite touch strip indicator  310 , can be a touch strip that can detect one or more types of gestures performed by a user on or near touch strip indicator  310 . For example, a user can perform a tap gesture (touch and release), a swipe gesture (e.g., swipe upward along touch strip indicator  310 , swipe downward along touch strip indicator  310 ), or a long hold gesture (touch and hold for at least a threshold amount of time). 
     The touch strip may be capacitive and, through sidewall  111  of housing  110 , a user&#39;s touch against sidewall  111  can be detected. Touch strip indicator  310  may serve to indicate to a user the region in which the user&#39;s touch is sensed. Any gesture performed significantly away from touch strip indicator  310  may be unlikely to be sensed by the touch strip. The touch strip located within housing  110  may represent the only user input component present on thermostat  300  through which a user can directly provide input to thermostat  300 . Additionally, a user may use an application or website executed on another computerized device to interact with thermostat  300 . 
     The tactile sensation when a user moves his finger over touch strip indicator  310  might be no different than sidewall  111 . Alternatively, touch strip indicator  310  may have a variance in protrusion or texture from sidewall  111  so that a user can determine the location of touch strip indicator  310  by touch. For instance, a multi-layer (e.g., 4 layer) pad print may be performed to create touch strip indicator  310  such that a subtle protrusion of touch strip indicator  310  is present. Such an arrangement may be beneficial when interacting with thermostat  300  in a darkened environment. 
     In the embodiment of thermostat  300 , touch strip indicator  310  and the corresponding touch strip are located on a right side of thermostat  300  when viewed from the front (such as seen in  FIG.  3   ). In other embodiments, the touch strip and corresponding touch strip indicator  310  may be present on a top, bottom, or left of sidewall  111 . In some embodiments, multiple touch strips may be present, such as on the left and right of sidewall  111 . 
       FIG.  4 A  illustrates an embodiment  400 A of a layer stack of a reflective cover. Embodiment  400 A can represent the layers of cover  120 . An outermost glass layer  410  may be present. Glass layer  410  may serve as a transparent layer. By not using a reflective coating or layer adjacent the ambient environment, small scratches or other physical wear that occurs on glass layer  410  might not significantly affect reflectivity, transmissivity, and/or the aesthetic properties of the cover. 
     Adjacent glass layer  410  may be optical coating layer  420 . Optical coating layer  420  may include multiple sublayers of dielectric coatings that create an interference pattern. Sublayers may alternate between having relatively low and relatively high refractive indexes. In some embodiments, the sublayers may alternate between layers of SiO2 and TiO2. Other dielectric materials that are used for optical coatings and anti-reflective coatings may alternatively be used. A total thickness of optical coating layer  420  may be 1.5 μm. In other embodiments, the total thickness of optical coating layer  420  is between 1 μm and 2 μm. In still other embodiments, the total thickness of optical coating layer  420  is less than 1 μm or greater than 2 μm. Optical coating layer  420  may be formed by performing a physical vapor deposition process on an inner surface of glass layer  410 . Optical coating layer  420  may be formed using various non-metallic coatings. Non-metallic coatings may serve to interfere less with radio waves emitted by the radar sensor or reflected by objects and are desired to be measured by the radar sensor. Such non-metallic coatings can include coatings such as TiO 2 , SiO 2 , NB 2 O 5 . A total of fewer than 10 or 15 sublayers may be present. 
     Within optical coating layer  420 , different thicknesses of sublayers of high and low refractive index coatings may be present. For instance, some number of non-metallic coatings may be present, with each having a different thickness, such as ranging from 10 nm to 510 nm. The various sublayers can serve to cause interference reflection of various wavelengths of light. 
     Optically-clear adhesive (OCA) layer  430  can serve to adhere optical coating layer  420  to anti-shatter film  440 . 
     Anti-shatter film  440  may serve to prevent the cover from shattering into potentially dangerous pieces if glass layer  410  is impacted by an object sufficient to cause damage. Masking  450 , where present on the cover, may serve to prevent any light internal to the thermostat from being transmitted through the cover into the ambient environment. Masking  450  may help enhance the effect that the mirror display is seamless. Similarly, masking  450 , where present on the cover, may prevent light from the ambient environment from penetrating into the interior of the thermostat. 
     Embodiment  400 A may generally have a neutral or silver tint to it. In other embodiments, a color tint may be desirable, such as for aesthetic reasons.  FIG.  4 B  illustrates embodiment  400 B of a layer stack of a reflective cover. For example, a rose or pink tinted cover may be desirable or a nickel tinted cover may be desirable. Embodiment  400 B may include: glass layer  410 ; OCA layer  430 ; coloring layer  460 ; mirror film  470 ; and masking  450 . Glass layer  410 , OCA layer  430 , and masking  450  may function as detailed in relation to embodiment  400 A. In embodiment  400 B, OCA layer  430  can adhere glass layer  410  with coloring layer  460 . 
     Coloring layer  460  may include a particular coloring, dye, or tinting that filters visible light to provide a particular visual tint, such as rose, nickel, or some other color. 
     Mirror film  470  may include multiple sublayers of polymers that create an interference pattern. A total thickness of mirror film  470  may be between 80 μm and 200 μm in thickness. Mirror film  470  may use polyethylene terephthalate (PET) within the sublayers. Such sublayers may be non-metallic. Non-metallic coatings may serve to interfere less with radio waves emitted by the radar sensor or reflected by objects and are desired to be measured by the radar sensor. Mirror film  470  may include more than one hundred sublayers that are on the order nanometers in thickness; in some embodiments, 1,000 layers or more are present. Composition of the sublayers are differentiated by applying differing amounts of strain to the layer in order to induce differences in the index of refraction. For aesthetic reasons, mirror film  470  may be preferable when used in combination with coloring layer  460 , such as when a coloring of rose or nickel is desired. If a silver appearance is desired, optical coating layer  420 , as used in embodiment  400 A may be preferable. 
       FIG.  5    illustrates an embodiment of thermostat mounting system  500 . Thermostat mounting system  500  can include: trim plate  510 ; backplate  520 ; fasteners  530 ; batteries  540 ; and thermostat  550 . Thermostat  550  can represent an embodiment of thermostat  100  of  FIG.  1    and the other thermostat embodiments detailed herein. Trim plate  510  may be plastic, wooden, or metallic plate that defines several holes to accommodate fasteners  530  and allow HVAC (heating, ventilation, and air conditioning) control wires to pass through. Trim plate  510  may serve to conceal any unsightly holes present in wall  501 , such as where previous drilling occurred, electrical boxes, paint mismatches, or other aesthetic variances. 
     Backplate  520  may include multiple receptacles, with each receptacle designated to receive a particular HVAC control wire. Backplate  520  can define one or more holes configured to receive fasteners  530 . Fasteners  530  can secure backplate  520  and, if being used, trim plate  510 , to a surface, such as a wall. 
     In some embodiments, two fasteners, fastener  530 - 1  and fastener  530 - 2  may be presented. Fasteners  530  may be screws, nails, or some other form of fastener. Fasteners  530  can securely hold backplate  520  and, possibly, trim plate  510  to a surface, such as a wall. Thermostat  550  may removably attach with backplate  520 . A user may be able to attach thermostat  550  to backplate  520  by pushing thermostat  550  against backplate  520 . Similarly, a user can remove thermostat  550  from backplate  520  by pulling thermostat  550  away from backplate  520 . When thermostat  550  is connected with backplate  520 , electrical connections between thermostat  550  and HVAC control wires that have been connected with the receptacles of backplate  520 . 
     In some embodiments, HVAC control wires can include a “C” wire, which stands for common wire. The C wire delivers power, such as in the form of 24 V AC, to thermostat  550 . Thermostat  550 , being connected with a C wire (and, possibly an “R” wire, which is typically red), can have access to a power supply that does not need to be periodically replaced or recharged, such as batteries  540 . In some embodiments, if a C wire is not present, thermostat  550  can function using batteries  540  as its exclusive power source. 
     Batteries  540 , which can include one or more batteries, such as battery  540 - 1  and battery  540 - 2 , can serve as a primary power source or as a backup power source. In some embodiments, one or more features of thermostat  550  can be disabled if only batteries  540  are available as a power supply. Batteries  540  may be replaceable by a user. Batteries  540  may be rechargeable. 
       FIG.  6    illustrates an embodiment of a smart thermostat system  600 . Smart thermostat system  600  can include smart thermostat  610 ; backplate  620 ; trim plate  630 ; network  640 ; cloud-based server system  650 ; and computerized device  660 . Smart thermostat  610  can represent any of the thermostats detailed in relation to  FIGS.  1 - 5   . Thermostat  610  can include: electronic display  611 ; touch sensor  612 ; radar sensor  613 ; network interface  614 ; speaker  615 ; ambient light sensor  616 ; temperature sensor  617 ; HVAC interface  618 ; processing system  619 ; housing  621 ; and cover  622 . 
     Electronic display  611  may be visible through cover  622 . In some embodiments, electronic display  611  is only visible when electronic display  611  is illuminated. In some embodiments, electronic display  611  is not a touch screen. Touch sensor  612  may allow one or more gestures, including tap and swipe gestures, to be detected. Touch sensor  612  may be a capacitive sensor that includes multiple electrodes. In some embodiments, touch sensor  612  is a touch strip that includes five or more electrodes. 
     Radar sensor  613  may be configured to output radio waves into the ambient environment in front of electronic display  611  of thermostat  610 . Radar sensor  613  may be an integrated circuit that includes one or more antennas, one or more RF emitters, and one or more RF receivers. Radar sensor  613  may be able to detect the presence of a user and the distance at which the user is located. Radar sensor  613  may use frequency-modulated continuous wave (FMCW) radar. Radar sensor  613  may emit radio waves and receive reflected radio waves through cover  622 . Radar sensor  613  may emit chirps of radar that sweep from a first frequency to a second frequency. Therefore, the waveform output by radar sensor  613  may be a saw tooth waveform. Using receive-side beam steering on the reflected radio waves received using multiple antennas, certain regions may be targeted for sensing the presence of users. For instance, beam steering away from the ground may be performed to avoid pets being potentially incorrectly detected as a user. 
     Network interface  614  may be used to communicate with one or more wired or wireless networks. Network interface  614  may communicate with a wireless local area network, such as a WiFi network. Additional or alternative network interfaces may also be present. For example, thermostat  610  may be able to communicate with a user device directly, such as using Bluetooth. Thermostat  610  may be able to communicate via a mesh network with various other home automation devices. Mesh networks may use relatively less power compared to wireless local area network-based communication, such as WiFi. In some embodiments, thermostat  610  can serve as an edge router that translates communications between a mesh network and a wireless network, such as a WiFi network. In some embodiments, a wired network interface may be present, such as to allow communication with a local area network (LAN). One or more direct wireless communication interfaces may also be present, such as to enable direct communication with a remote temperature sensor installed in a different housing external and distinct from housing  621 . The evolution of wireless communication to fifth generation (5G) and sixth generation (6G) standards and technologies provides greater throughput with lower latency which enhances mobile broadband services. 5G and 6G technologies also provide new classes of services, over control and data channels, for vehicular networking (V2X), fixed wireless broadband, and the Internet of Things (IoT). Thermostat  610  may include one or more wireless interfaces that can communicate using 5G and/or 6G networks. 
     Speaker  615  can be used to output audio. Speaker  615  may be used to output beeps, clicks, or other audible sounds, such as in response to the detection of user input via touch sensor  612 . 
     Ambient light sensor  616  may sense the amount of light present in the environment of thermostat  610 . Measurements made by ambient light sensor  616  may be used to adjust the brightness of electronic display  611 . In some embodiments, ambient light sensor  616  senses an amount of ambient light through cover  622 . Therefore, compensation for the reflectivity of cover  622  may be made such that the ambient light levels are correctly determined via ambient light sensor  616 . A light pipe may be present between ambient light sensor  616  and cover  622  such that in a particular region of cover  622 , light that is transmitted through cover  622 , is directed to ambient light sensor  616 , which may be mounted to a printed circuit board (PCB), such as a PCB to which processing system  619  is attached. 
     One or more temperature sensors, such as temperature sensor  617 , may be present within thermostat  610 . Temperature sensor  617  may be used to measure the ambient temperature in the environment of thermostat  610 . One or more additional temperature sensors that are remote from thermostat  610  may additionally or alternatively be used to measure the temperature of the ambient environment. 
     Cover  622  may have a transmissivity sufficient to allow illuminated portions of electronic display  611  to be viewed through cover  622  from an exterior of thermostat  610  by a user. Cover  622  may have a reflectivity sufficient such that portions of cover  622  that are not illuminated from behind appear to have a mirrored effect to a user viewing a front of thermostat  610 . 
     HVAC interface  618  can include one or more interfaces that control whether a circuit involving various HVAC control wires that are connected either directly with thermostat  610  or with backplate  620  is completed. A heating system (e.g., furnace, heat pump), cooling system (e.g., air conditioner), and/or fan may be controlled via HVAC wires by opening and closing circuits that include the HVAC control wires. 
     Processing system  619  can include one or more processors. Processing system  619  may include one or more special-purpose or general-purpose processors. Such special-purpose processors may include processors that are specifically designed to perform the functions detailed herein. Such special-purpose processors may be ASICs or FPGAs which are general-purpose components that are physically and electrically configured to perform the functions detailed herein. Such general-purpose processors may execute special-purpose software that is stored using one or more non-transitory processor-readable mediums, such as random access memory (RAM), flash memory, a hard disk drive (HDD), or a solid state drive (SSD) of thermostat  610 . 
     Processing system  619  may output information for presentation to electronic display  611 . Processing system  619  can receive information from touch sensor  612 , radar sensor  613 , and ambient light sensor  616 . Processing system  619  can perform bidirectional communication with network interface  614 . Processing system  619  can output information to be output as sound to speaker  615 . Processing system  619  can control the HVAC system via HVAC interface  618 . 
     Housing  621  may house all of the components of thermostat  610 . Touch sensor  612  may be interacted with a user through housing  621 . Housing  621  may define a sidewall and an aperture, such as a rounded aperture (e.g., a circular aperture) in which cover  622  is present. 
     Thermostat  610  may be attached (and removed) from backplate  620 . HVAC control wires may be attached with terminals or receptacles of backplate  620 . Alternatively, such control wires may be directly connected with thermostat  610 . In some embodiments, trim plate  630  may additionally be installed between backplate  620  and a surface, such as a wall, such as for aesthetic reasons (e.g., cover an unsightly hole through which HVAC wires protrude from the wall. 
     Network  640  can include one or more wireless networks, wired networks, public networks, private networks, and/or mesh networks. A home wireless local area network (e.g., a Wi-Fi network) may be part of network  640 . Network  640  can include the Internet. Network  640  can include a mesh network, which may include one or more other smart home devices, may be used to enable thermostat  610  to communicate with another network, such as a Wi-Fi network. Thermostat  610  may function as an edge router that translates communications from a relatively low power mesh network received from other devices to another form of network, such as a relatively higher power network, such as a Wi-Fi network. 
     Cloud-based server system  650  can maintain an account mapped to smart thermostat  610 . Thermostat  610  may periodically or intermittently communicate with cloud-based server system  650  to determine whether setpoint or schedule changes have been made. A user may interact with thermostat  610  via computerized device  660 , which may be a mobile device, smartphone, tablet computer, laptop computer, desktop computer, or some other form of computerized device that can communicate with cloud-based server system  650  via network  640  or can communicate directly with thermostat  610  (e.g., via Bluetooth or some other device-to-device communication protocol). A user can interact with an application executed on computerized device  660  to control or interact with thermostat  610 . 
       FIGS.  7  through  13    illustrate various user interfaces that may be used by embodiments of smart thermostats, as detailed herein.  FIG.  7    illustrates an embodiment of a default user interface that may be presented by thermostat  700 . Thermostat  700  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 6   . Thermostat  700  may present such an interface when a user is detected in a vicinity of thermostat  700 , such as via radar sensor  613 . Besides being detected, a user might not have provided any input to cause the interface to be presented. Additionally or alternatively, the interface may be presented when a user has exited from a main menu, such as detailed in relation to  FIG.  10   , or selected a particular icon or option from the main menu. Setpoint temperature  710  may be presented in the middle of the electronic display and may indicate the temperature to which the environment is being warmed. Setpoint temperature  710  may be presented in a larger size than other information presented on the display screen of thermostat  700 . 
     Message  705  may indicate that heating is enabled and make clear to a user that setpoint temperature  710  is indicative of a temperature to which the environment of thermostat  700  is being heated. If instead of heating, cooling was enabled, message  705  may indicate something similar to “Cooling set to” to indicate that cooling is activated. Message  715  may indicate what the current measured temperature the thermostat&#39;s environment is, such as measured by temperature sensor  617 . 
     In some embodiments, message  705  switches between presenting two or more pieces of information. A ranked listing of types of information may be stored. Some number of the highest ranking pieces of information that are available for output may be presented as message  705  and periodically switched between. For instance, a low battery message may also be presented as message  705 . In this example, periodically, such as every two seconds, message  705  may rotate between reading “Heat set to” and “Low Battery,” or any other two messages that are selected for presentation based on having the highest rank. 
     A user swiping up or swiping down on the touch sensor of thermostat  700  can cause setpoint temperature  710  to be adjusted up or down, respectively. The shorter the swipe, the smaller the adjustment in temperature. A fast swipe may cause the temperature to rapidly be adjusted, while a slow swipe may cause the temperature to slowly change. A fast swipe may cause the temperature to change in greater increments than a slow swipe. For example, a fast swipe may cause the temperature to adjust by 2 or 3 degrees (or some other, higher value) at a time; a slow swipe may cause the temperature to adjust by 0.5 or 1 degree (or some other, smaller value) at a time. 
       FIG.  8    illustrates an embodiment of a default user interface that may be presented by thermostat  800  when a dual heating-cooling mode is enabled. Thermostat  800  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 7   . For thermostat  800 , a joint heating and cooling mode is enabled in which a temperature setpoint range  810  is defined for heating and cooling. Cooling is used to keep the temperature at or below the higher setpoint temperature and heating is used to keep the temperature at or above the lower setpoint temperature. Temperature  815  indicates the current temperature measured by thermostat  800 . 
     For thermostat  800 , message  805  displays “Comfort” with a graphical heart. A user may define multiple preset setpoint temperatures or setpoint temperature ranges. In the example of thermostat  800 , a user has defined a preset temperature range named “comfort” as corresponding to the temperature range of 69° F.-75° F. Other predefined setpoint temperatures or setpoint temperature ranges may be possible, such as “Eco” and “sleep” modes. Such predefined setpoint temperatures or setpoint temperature ranges may be helpful to a user when creating a schedule: for a given time period, a user can select one of the predefined and named temperature setpoints or setpoint ranges rather than directly entering a specific numerical setpoint temperature value. For each predefined temperature setpoint or setpoint range, a graphical symbol may be displayed that represents the predefined setpoint temperature or setpoint temperature range. For example, a heart may be displayed for “comfort,” a leaf may be displayed for “eco,” and a bed may be displayed for “sleep.” 
     For thermostat  700  and thermostat  800 , the setpoint temperatures and words may be presented in a color, such as white, that is indicative of neither heating or cooling of the HVAC system being activated. In  FIG.  9   , thermostat  900  illustrates an embodiment of a default user interface that may be presented by thermostat  900  when heating is active while a dual heating-cooling mode is enabled. Thermostat  900  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 8   . To indicate that heating is active, lower setpoint  910 , which is the controlling temperature for heating, may be emphasized using color and/or brightness. For example, temperature setpoint  910  can be displayed in red, red/orange, or orange to indicate heating is active. Higher setpoint  915  used for cooling (75° F. in this example) may be indicated in white or blue. Additionally, setpoint  915  may be deemphasized by the value not being displayed as bright as setpoint  910 . If cooling was active instead of heating, the reverse situation would be true: setpoint temperature  915  would be emphasized (e.g., brighter), while the setpoint  910  would be deemphasized. Other forms of emphasis are possible, such as the size of the setpoint, bolding the setpoint, flashing the setpoint, etc. 
     Message  905  may indicate whether heating or cooling is active. If heating is active, message  905  may be displayed in a same color as setpoint  910 . If cooling is active, message  905  may be displayed in a same color as setpoint  915 . An icon or other form of graphic may be presented as part of message  905  that is indicative of active heating or cooling. For example, a flame may be indicative of heating and a snowflake may be indicative of cooling. The icon or graphic may use the same color as the remainder of message  905 . 
     Message  920  may present the current measured ambient temperature, possibly along with a location at which the temperature was measured. For instance, “indoor” may indicate that the temperature was measured using temperature sensor  617 . An outdoor temperature may occasionally be presented that is indicative of a temperature retrieved from a remote server for the general location of the thermostat. 
       FIG.  10    illustrates an embodiment of a thermostat  1000  presenting a main menu. The main menu may be presented in response to a user tapping or touching and holding a touch sensor, such as a touch strip, of thermostat  1000 . Thermostat  1000  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 9   . To navigate the main menu, a user can interact with the touch strip. The user may swipe down to move selection to lower icons of selectable icons  1015 . The user may swipe up to move selection to higher icons of selectable icons  1015 . The currently selected icon may be emphasized, such as by being brighter and/or larger than other icons. In some embodiments, color is used to emphasize the selected icon. In order to return back to the default interface, a user may highlight and select a back icon, which in some embodiments is represented by an arrow pointed left. Selection of an icon may be accomplished by a user tapping the touch sensor while the icon is emphasized. 
     The main menu may also include additional information, such as information  1005 . 
     Information  1005  may include weather information, outdoor temperature information, the day, and/or the time. Such information may be retrieved from a remote server or may be tracked by the thermostat. Information  1010  may indicate the indoor temperature and indoor humidity. Icons or graphics may be used to indicate at least some of information  1005  and information  1010  graphically. For example, weather information may be indicated using graphics such as the sun, clouds, rain, snow, wind, etc. A graphic indicating a temperature that corresponds to the indoor temperature may include a graphic of a house. A graphic indicating the relative humidity may be a raindrop. 
       FIG.  11    illustrates an embodiment of a thermostat  1100  presenting a main menu on which a warning is present. Thermostat  1100  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 10   . An icon, such as a gear, may be used to indicate thermostat settings. If there is a problem that needs to be addressed by a user, the setting icon may be changed to alert the user to the problem. For instance, an exclamation point, which may be colored, may be presented on the settings icon, such as on icon  1105 . Additionally or alternatively, text may be presented that indicates the nature of the problem. For instance, “low battery” may be presented as message  1107  to indicate the nature of the problem that needs to be addressed by the user. If no problem is present, message  1107  might not be displayed. Message  1106  may indicate text that corresponds to the current icon selection. Since icon  1106  is selected, message  1106  indicates “settings.” 
     Angle  1115  and angle  1116 , originating from a center of cover  1101  of thermostat  1100 , indicates the relationship that can exist between icons or graphics of a menu, such as a main menu, and the location and length of a touch sensor, such as a touch strip. Arc  1110  represents the location and angle of a touch strip that is interacted with by a user via a sidewall of thermostat  1100 , such as indicated by touch strip indicator  310  of  FIG.  3 B . To allow for more intuitive input from a user, the arrangement of multiple icons or graphics may approximately or exactly match the shape and position of the touch strip. On the user interface of thermostat  1100 , icons are presented in an arc from angle  1115  to angle  1116 . Angle  1115  and angle  1116  also correspond to the ends of the touch strip corresponding to arc  1110 . In some embodiments, the entirety of the region on the sidewall of the housing on which a user can provide touch input is within the arc defined by angle  1115  and angle  1116 . In some embodiments, the region on the sidewall of the housing on which a user can provide touch input approximately (e.g., within +/−10°, within +/−5°) corresponds to arc  1110  defined by angle  1115  and angle  1116 . 
     In some embodiments, a downward swipe gesture along an entirety of arc  1110  on the touch sensor may be sufficient to move selection from a top icon of the menu to a bottom icon of the menu. Similarly, an upward swipe gesture along an entirety of arc  1110  on the touch sensor may be sufficient to move selection from a bottom icon of the menu to a top icon of the menu. As such, to navigate the menu, a user might not need to perform more than one swipe gesture. A tap gesture can be performed to select an icon and present the icon&#39;s associated submenu. In some embodiments, a touch and hold gesture (where the hold is performed for at least a threshold amount of time) may perform an alternative function, such as returning to the previous menu or default interface or jumping to a user-selected favorite interface. 
       FIG.  12    illustrates an embodiment of a thermostat  1200  presenting a heating/cooling menu. Thermostat  1200  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 11   . Thermostat  1200  is presenting a heating/cooling menu. In the heating/cooling menu, a user can select whether a heating mode should be enabled, a cooling mode should be enabled, or a combined heating and cooling mode should be enabled. In the heating mode, only the heating source controlled by thermostat  1200  may be eligible for activation. In the cooling mode, only the cooling source controlled by thermostat  1200  may be eligible for activation by thermostat  1200 . In the heating/cooling mode, which is indicated by a split flame/snowflake icon, thermostat  1200  may be authorized to activate either heating or cooling based on a range of defined temperature setpoints (e.g., a low temperature setpoint for heating and a high temperature setpoint for cooling) such as detailed in relation to  FIGS.  8  and  9   . Since heating/cooling mode is currently emphasized, message  1205  indicates text corresponding to heating/cooling mode. Message  1210  may serve as a reminder for the user how to select the currently emphasized icon. 
     In some embodiments, no more than a predefined number of selectable icons may be presented at a time, such as to allow the icons to match or remain within angles  1115  and angle  1116 .  FIG.  13    illustrates an embodiment of thermostat  1300  in which a “more items available” icon is present on a menu. Thermostat  1300  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 12   . In some embodiments, no more than five icons may be presented at a time, such as to allow all presented icons to be approximately within angle  1115  and angle  1116 . 
     Icon  1305  may be presented as part of a menu but might not be selectable. The presence of icon  1305  may signal to a user that additional icons are available for presentation and selection if the user scrolls down, such as by swiping down. When swiping down toward icon  1305 , an icon at the top of the menu may be hidden and an additional, selectable icon may be presented at the bottom of the menu. Icon  1305  may be presented at the top of the menu if additional icons will be presented if a user scrolls upward. Icon  1305  may disappear at the bottom of the menu when no additional icons are available to be presented at the bottom of the menu. Similarly, icon  1305  may only be presented as a top icon when additional icons are available to be presented at the top of the menu. Icon  1305  may be presented at both the top and bottom at a same time if additional icons are available in both directions. 
     As previously detailed, a radar sensor may be incorporated as part of the various detailed embodiments of thermostats.  FIG.  14    illustrates a top view of an embodiment of a thermostat using radar to sense for a user in an ambient environment of the thermostat. Thermostat  1400  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 13   . Thermostat  1400  can have a radar sensor, such as radar sensor  613 , that emits radio waves, such as having a frequency between 58-62 GHz, into the ambient environment of thermostat  1410 . The emitted radar may be FMCW radar, such as in a saw tooth pattern. Reflected radio waves that are received by the radar sensor may be reflected by stationary and moving objects. By using FMCW, a distance to an object may be determined. Therefore, in contrast to passive infrared sensing, it may be possible to determine a distance to a user. 
     In some embodiments, based on a distance at which a user is detected, different information may be presented by the electronic display of thermostat  1410 . For example, outside of far distance range  1422 , the electronic display of thermostat  1410  may be turned off. Within far distance range  1422 , a basic setpoint temperature display may be presented, such as just the temperature as indicated in  FIG.  2   . Within middle distance range  1421 , a greater amount of detail may be presented on the display, such as default interfaces, such as those of  FIG.  7 ,  8   , or  9 . Within a near distance range  1420 , a still greater (or different) amount of information may be presented. For instance, the presented interfaces may be augmented with weather, time, and/or humidity data. In other embodiments, as the distance to a user changes as measured by thermostat  1410 , greater or fewer numbers of different interfaces may be presented. 
     In some embodiments, whether the display of thermostat  1410  is activated may be based on whether the user is detected as moving toward or away from thermostat  1410 . Using radar, a direction of movement of the user, such as indicated by arrow  1430  or arrow  1440  may be determined. If the user is moving away from thermostat  1410 , the display of thermostat  1410  may be disabled or the brightness decreased. If the user is moving toward thermostat  1410 , the display of thermostat  1410  may be enabled or the brightness increased. 
     In order to detect whether a user is moving toward or away from thermostat  1410 , data across multiple radar chirps may be analyzed. For a given emitted chirp, a reflected radar chirp may be received by the radar sensor, possibly through cover  622 . The reflected radar chirp may be mixed with a portion of the radar chirp about to be emitted to get baseband raw waveform data. The frequency of the baseband raw waveform data, which is indicative of the difference between the currently-being emitted radar and the received radar, is indicative of the distance to the object that reflected the radar. Filtering may be performed to remove reflections due to static objects. Therefore, a filtered set of waveform data may be indicative of radar reflected by moving objects. 
     A Fast Fourier transform (FFT) may be performed across the filtered waveform data from multiple chirps. This performed FFT may be indicative of a velocity at which a moving object is moving toward or away from the radar sensor. Therefore, for example, a positive velocity may be indicative of a user moving toward the thermostat while a negative velocity may be indicative of a user moving away from the thermostat. Based upon the speed at which a user is moving toward the thermostat, the information or interface presented may be selected. For instance, if the user is moving relatively quickly toward the thermostat, a different interface may be presented than if the user is relatively slowly moving toward the thermostat. 
     Additionally or alternatively, a FFT may be performed on the filtered waveform data for a single chirp. As previously noted, reflected received radio waves are mixed with radio waves being transmitted. Due to propagation delay of electromagnetic radiation, the frequency obtained by mixing will vary based on the distance to the object that reflected the radio waves. After filtering out reflections due to static objects, a FFT may be performed on the filtered waveform data. The predominant frequency identified by the FFT can be indicative of the distance at which the user is located. In addition or in alternate to the direction and/or speed at which a user is moving, the distance at which the user is located may be used to determine whether and which interface should be presented by thermostat  1410 . 
       FIG.  15    illustrates an embodiment of thermostat  1500  with its cover removed as viewed from a front of thermostat  1500 . Thermostat  1500  can represent thermostat  100  or any of the other embodiments of a thermostat detailed in relation to  FIGS.  1 - 14   . With the cover removed, printed circuit board (PCB)  1501  may be visible. PCB  1501  may be housed by housing  1505  (which corresponds to housing  621 ). PCB  1501  may be rounded, such as circular in shape. Attached with PCB  1501  may be electronic display  1510 , temperature sensor  1520 , ambient light sensor  1530 , and radar sensor  1540 . Electronic display  1510  may be generally rectangular in shape. While display  1510  does not span the entire surface of PCB  1501 , when the cover is present, it might not be possible for a user to see edge  1511  of display  1510 . Therefore, while display  1510  may be rectangular in shape, this shape might not be discernable through the cover, when present. 
     Ambient light sensor  1530  may be attached with PCB  1501 . A light pipe, such as made from translucent or transparent plastic, may be present that directs light that passes through a portion of the cover to ambient light sensor  1530 . The light pipe may contact ambient light sensor  1530  and a back side of the cover, when present. However, no lens, hole, or other incongruity may be present on the cover for the light pipe or ambient light sensor  1530 . 
     Temperature sensor  1520 , which corresponds to temperature sensor  617  and is used to measure the ambient temperature of the environment of thermostat  1500 , may be isolated from heat sources on PCB  1501 . Such isolation may be performed by locating temperature sensor  1520  away from other electronic components (e.g., processors, wireless network interfaces, display  1510 ) that generate heat. Additionally or alternatively, one or more cutouts on PCB  1501  may be present to decrease heat transfer through the PCB from heat-generating components to temperature sensor  1520 . 
     Radar sensor  1540 , which corresponds to radar sensor  613  of  FIG.  6   , may be located to avoid metallic components of thermostat  1500  and components that could create interference, such as a wireless network interface. Particularly, radar sensor  1540  might be located on PCB  1501  such that it is located behind a cover (when present), but not behind display  1510 . Display  1510  may include metallic shielding that could negatively impact the ability of radar sensor  1540  to transmit and receive radio waves into the ambient environment of thermostat  1500 . Therefore, radar sensor  1540  may be positioned such that it can transmit radio waves into the ambient environment and receive reflected radio waves through the cover, but not through display  1510 . Radar sensor  1540  may be a single integrated chip (IC), such as detailed in relation to  FIG.  17   . 
     In some embodiments, a space may be present between radar sensor  1540  and a cover of thermostat  1500 , when present. This space may be open, in that it is filled with air, but no components. The distance from the antennas of the radar sensor to the cover may be approximately one-fourth of a wavelength or some other odd multiple of one-fourth of a wavelength. Such a distance may help decrease constructive reflections by the cover that could be received by one or more antennas of radar sensor  1540 . If FMCW is used by the radar sensor, a sweep from a first frequency to a second frequency is performed. Therefore, the distance may be selected to minimize constructive reflections across the frequency range of the frequency sweep. 
       FIG.  16    illustrates chirp timing diagram  1600  for frequency modulated continuous wave (FMCW) radar radio waves output by a radar subsystem. Chirp timing diagram  1600  is not to scale. Radar sensor  613  may generally output radar in the pattern of chirp timing diagram  1600 . Chirp  1650  represents a continuous pulse of radio waves that sweeps up in frequency from a low frequency to a high frequency. In other embodiments, individual chirps may continuously sweep down from a high frequency to a low frequency. In some embodiments, the low frequency is 61 GHz and the high frequency is 61.5 GHz. (For such frequencies, the radio waves may be referred to as millimeter waves.) The low frequency and the high frequency may be varied by embodiment. For instance, the low frequency may be between 40 and 60 GHz, and the high frequency may be between 45 GHz and 80 GHz. In some embodiments, the low frequency is between 57 GHz and 63 GHz and the high frequency is greater than the low frequency and is also between 57 GHz and 63 GHz. In some embodiments, each chirp includes a linear sweep from a low frequency to a high frequency (or the reverse). In other embodiments, an exponential or some other pattern may be used to sweep the frequency from low to high or high to low. The shape of the chirp (as defined by the bandwidth sweep and chirp duration) may be designed to meet a particular distance detection requirement. 
     Chirp  1650 , which can be representative of all chirps in chirp timing diagram  1600 , may have chirp duration  1652  of 128 μs. In other embodiments, chirp duration  1652  may be longer or shorter, such as between 30 μs and 600 μs. In some embodiments, a period of time may elapse before a subsequent chirp is emitted. Chirp period may be 500 μs, thus meaning the chirps repeat at 2 kHz. In other embodiments chirp period  1654  may be between 100 μs and 1 ms. This duration varies based on the selected chirp duration  1652  and inter-chirp pause  1656 . 
     A number of chirps that are output, separated by inter-chirp pauses, may be referred to as burst  1658  or frame  1658 . Frame  1658  may include sixteen chirps. In other embodiments, the number of chirps in frame  1658  may be greater or fewer, such as between one and one hundred. The number of chirps present within frame  1658  may be determined based upon the average power that is to be radiated. By limiting the number of chirps within frame  1658  prior to an inter-frame pause, the average output power may be limited. In some embodiments, the peak power radiated by a radar subsystem may be 13 dBm, 7 dBm, 5 dBm. In other embodiments, the peak power radiated may be greater than 13 dBm or less than 5 dBm. That is, at any given time, the amount of power radiated by the radar subsystem never exceeds such values. 
     The number of chirps and the rate at which chirps are repeated in a frame can be adjusted based on velocity detection requirements of the device. The number of chirps per frame and the frame repetition rate can be used to limit the on time of RF transmissions, which reduces the power consumption of the product. A reduced power mode may be used until an event is detected, and then power consumption may be increased to send more chirps to collect more data to better assess the environment. The more chirps transmitted can result in more data collected, which can in some cases be averaged or analyzed to obtain a higher signal to noise reading of the data. 
     The FCC or other regulatory agency may set a maximum amount of power that is permissible to be radiated into an environment on average. For example, a duty cycle requirement may be present that limits the duty cycle to less than 10% for any 33 ms time period. In one particular example in which there are twenty chirps per frame, each chirp can have a duration of 128 us, and each frame being 33.33 ms in duration. The corresponding duty cycle is (20 frames)*(0.128 ms)/(33.33 ms), which is about 7.8%. By limiting the number of chirps within frame  258  prior to an inter-frame pause, the total amount of power output may be limited. In some embodiments, the peak EIRP (effective isotropically radiated power) may be 13 dBm (20 mW) or less, such as 12.86 dBm (19.05 mW). In other embodiments, the peak EIRP is 15 dBm or less and the duty cycle is 15% or less. In some embodiments, the peak EIRP is 20 dBm or less. That is, at any given time, the average power radiated over a period of time by the radar subsystem might be limited to never exceed such values. Further, the total power radiated over a period of time may be limited. In some embodiments, a duty cycle is not be required. 
     Frames may be transmitted at a frequency of 5-10 Hz as shown by time period  1660 . In other embodiments, the frequency may be higher or lower. The frame frequency may be dependent on the number of chirps within a frame and the duration of inter-frame pause  1662 . For instance, the frequency may be between 1 Hz and 50 Hz. In some embodiments, chirps may be transmitted continuously, such that the radar subsystem outputs a continuous stream of chirps interspersed with inter-chirp pauses. Inter-frame pause  1662  represents a period of time when no chirps are output. In some embodiments, inter-frame pause  1662  is significantly longer than the duration of frame  1658 . 
     In the illustrated embodiment of  FIG.  16   , a single frame  1658  and the start of a subsequent frame are illustrated. It should be understood that each subsequent frame can be structured similarly to frame  1658 . Further, the transmission mode of the radar subsystem may be fixed. That is, regardless of whether a user is present or not, the time of day, or other factors, chirps may be transmitted according to chirp timing diagram  1600 . Therefore, in some embodiments, the radar subsystem always operates in a single transmission mode, regardless of the state of the environment (e.g., whether likely occupied, not occupied, or occupants are likely asleep or not). A continuous train of frames similar to frame  1658  may be transmitted while the thermostat is powered on. 
     In some embodiments, the radar sensor is not be powered if the batteries are low on power and/or no C-wire is connected with the thermostat. In such embodiments, the thermostat may operate in a touch-to-activate mode in which a user is required to touch the touch sensor in order to activate a display of the thermostat. When touched, the thermostat may default to an interface such as presented in  FIGS.  7 - 9   . 
       FIG.  17    illustrates an embodiment of a radar sensor  1700  that may be used by a thermostat. Radar sensor  1700  may represent an embodiment of radar sensor  613  and the other embodiments of radar sensors. The entirety of the radar sensor can be a single integrated circuit. The entire IC may have dimensions of 6.5 mm (length  1705 ) by 5 mm (width  1704 ). In other embodiments, the entire IC has a length  1705  by width  1704  of between 7 mm by 7 mm and 4 mm by 4 mm. The illustrated embodiment of radar subsystem  205  has three receive antennas and one transmit antenna, but other embodiments may have a greater or fewer number of antennas. Radar sensor  1700  may have receive antennas  1710 - 1 ,  1710 - 2 , and  1710 - 3  distributed in an “L” pattern. That is, antennas  1710 - 1  and  1710 - 2  may be aligned on axis  1701  and antennas  1710 - 2  and  1710 - 3  may be aligned on axis  1702  which is perpendicular to axis  1701 , as illustrated in  FIG.  17   . The center of antenna  1710 - 2  may be located 2.5 mm or less from the center of antenna  1710 - 1 . The center of antenna  1710 - 2  may be located 2.5 mm or less from the center of antenna  1710 - 3 . 
     Transmit antenna  1710 - 4  may be arranged separately from the L-shaped pattern of the receive antennas  1710 - 1 ,  1710 - 2 , and  1710 - 3 . That is, in some embodiments, a center of transmit antenna  1710 - 4  is not be located on an axis with antenna  1710 - 3  that is parallel to axis  1701 . In some embodiments, transmit antenna  1710 - 4  is on axis  1703  with center of antenna  1710 - 1 , with axis  1703  being parallel to axis  1702 . 
     Each of antennas  1710  may be hollow rectangular dielectric resonance antennas (DRAs). Each of antennas  1710  may have a same set of dimensions. Alternatively, each of receive antennas  1710 - 1 ,  1710 - 2 , and  1710 - 3  may have the same dimensions and transmit antenna  1710 - 4  may vary in dimensions from the receive antennas. In some embodiments, transmit antenna  1710 - 4  has a larger width, such as 0.2 mm larger, than receive antennas  1710 - 1 ,  1710 - 2 , and  1710 - 3 , but the same length. 
     In such an arrangement, the phase delay introduced by applied weights between the antenna data stream of antenna  1710 - 1  and the data stream of antenna  1710 - 2  may affect the vertical direction of the receive beam and the phase delay introduced by weights between the antenna data stream of antenna  1710 - 2  and data stream of antenna  1710 - 3  may affect the horizontal direction of the receive beam (assuming the radar subsystem integrated circuit is present within the contactless sleep tracking device in approximately the same orientation). For instance, beam steering may be performed to deemphasize moving objects in the direction of the floor (e.g., more than 0°, 5°, 10°, or some other angle below horizontal) to decrease false detection of a user (e.g., due to a pet). 
     In some embodiments, separate antennas are used for transmitting and receiving. For example, antenna  1710 - 4  may be used exclusively for transmitting, while antennas  1710 - 1 ,  1710 - 2 , and  1710 - 3  are used exclusively for receiving. 
     In some embodiments, antenna  1710 - 3  may be deactivated, such as to save power. Therefore, despite three receive antennas being present, waveform data streams may only be output for antennas  1710 - 1  and  1710 - 2 . These two antennas may be understood to be vertically aligned such that when the thermostat is installed on a wall, antenna  1710 - 1  is directly above antenna  1710 - 2 . Such vertically-aligned receive antennas can allow beam steering to be performed vertically, such as to avoid areas near the ground where a pet might reside. 
       FIG.  18    illustrates an embodiment of a touch strip  1800 . Touch strip  1800  may be used as touch sensor  612  of  FIG.  6   . Touch strip  1800  may be affixed to an inside of housing  621  such that a user can provide input via the user&#39;s finger moving along an exterior sidewall of housing  621  opposite the interior portion of housing  621  to which touch strip  1800  is attached. Touch strip  1800  may be curved (as indicated by arc  1806 ) along a length of touch strip  1800  to allow touch strip  1800  to be flexed in an arc and lay flat against the interior of a sidewall of housing  621 . The sidewall of housing  621  may have a radius that varies in length between the thermostat&#39;s cover and a back of housing  621  that attaches with a backplate or mounts to a wall. Thus, the curvature indicated by arc  1806  can help touch sensor  1800  make contact with the interior surface of the sidewall. 
     Touch strip  1800  can include multiple electrodes. For example, 16 electrodes may be present. In other embodiments, greater (e.g., 20, or 20 or more electrodes) or fewer numbers of electrodes (e.g., 4, 6, 8, or fewer electrodes) are present. For simplicity in  FIG.  18   , only three electrodes are labeled: electrode  1801 , electrode  1802 , and electrode  1803 . 
     The electrodes of touch strip  1800  may be shaped in a “Z” or in zig-zag pattern. More generally, two electrodes, such as electrodes  1801  and  1802 , can intersect an axis  1804  that is generally perpendicular to the length of touch strip  1800 , as indicated by axis  1805 . By having regions that overlap along a perpendicular axis, when a user moves their finger along touch strip  1800 , the user&#39;s finger will be detected across multiple electrodes. For instance, as the user slides his finger from left to right across electrodes  1801  and  1802 , capacitive measurements obtained from electrode  1801  will decrease while capacitive measurements obtained from electrode  1802  will increase. By having overlap along axis  1804 , the decrease and increase in measurements between adjacent electrodes can be more gradual as the user swipes their finger. By having the increase and decrease in measurements be more gradual as the user&#39;s finger slides, the processing system of the thermostat can resolve finer movements of the user&#39;s finger (or fingers). This finer movement can be translated by the processing system into more precise and/or finer movements among setpoint temperatures and/or scrolling within menus of the thermostat interface. 
       FIG.  19    illustrates an embodiment  1900  of touch strip  1905  flexed in an arc for mounting to an interior surface of housing  1915 . Housing  1915  can represent housing  621  of  FIG.  6    or any other housing detailed herein. Touch strip  1905  can represent touch sensor  612 , touch strip  1800 , or any other touch strip detailed herein. To mount to interior surface  1920 , touch strip  1905  may be flexed in an arc and attached with interior surface  1920 , which represents an interior surface of housing  1915  along the sidewall. Touch strip  1905  may be attached using an adhesive and may remain generally in the shape of an arc. Since the radius of sidewall  1916  varies from a front (where a cover would be located) of housing  1915  to a back, the curvature of touch strip  1905 , represented by arc  1806  in  FIG.  18   , can allow touch sensor  1905  to be situated flat against interior surface  1920 . 
     Various methods may be performed using the systems, devices, components, and interfaces detailed in reference to  FIGS.  1 - 19   .  FIG.  20    illustrates an embodiment of a method  2000  for interacting with a smart thermostat. The thermostat used to perform method  2000  can be the thermostat embodiments detailed in relation to  FIGS.  1 - 19   . At block  2010 , radio waves are emitted by a radar sensor. The radar emitted may be FMCW radar. Radar chirps can be emitted as detailed in relation to  FIG.  16   . The radar may be emitted through a visually reflective cover of the thermostat in the ambient environment of the thermostat. 
     At block  2020 , radio waves are reflected off of moving and stationary objects and reflected back toward the thermostat. The radar sensor can receive the reflected radio waves through the visually-mirrored cover. This cover can be non-metallic to prevent reflection of emitted radio waves and radio waves reflected by objects in the ambient environment. 
     At block  2030 , a determination of whether a user is present may be at least partially based on the reflected radio waves received by the radar sensor at block  2020 . In some embodiments, block  2030  additionally or alternatively involves detecting whether the user is moving toward or away from the radar sensor, the distance at which the user is located, and/or a velocity at which the user is moving. 
     At block  2040 , an electronic display may be activated such that information is presented and visible by the user in response to detection of the user at block  2030  (and/or the user&#39;s distance, direction, and/or velocity). The electronic display may present a user interface such as present in  FIG.  7    or any other default user interface, such as presented in  FIGS.  8 - 10   , or some other default user interface. 
     At block  2050 , the user may interact with the thermostat via a touch sensor, such as a touch strip. The user interface presented is altered in response to the user performing a gesture on the touch strip. The gesture could be a tap gesture, a swipe upward gesture, a swipe downward gesture, or a touch-and-hold gesture. Other gestures may also be possible. Input provided via the touch strip may be used to alter the presented user interface and/or control operation of the thermostat at block  2060 . For example, a user can provide input via the touch strip that activates an HVAC system, deactivates an HVAC system, adjusts a control schedule used to control the HVAC system, adjust a setpoint of the HVAC system, alters settings of the thermostat, etc. 
     The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative configurations, the methods may be performed in an order different from that described, and/or various stages may be added, omitted, and/or combined. Also, features described with respect to certain configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims. 
     Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure. 
     Also, configurations may be described as a process which is depicted as a flow diagram or block diagram. Although each may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process may have additional steps not included in the figure. Furthermore, examples of the methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments to perform the necessary tasks may be stored in a non-transitory computer-readable medium such as a storage medium. Processors may perform the described tasks. 
     Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of the invention. Also, a number of steps may be undertaken before, during, or after the above elements are considered.