Environmental monitoring device

The disclosure is directed to a sensor device including processing circuitry, at least one sensor coupled to the processing circuitry, a serial data interface coupled to the processing circuitry and memory responsive to the processing circuitry. The memory includes a static unique identification number. The serial data interface provides access to retrieve the static unique identification number and sensed data measured with the at least one sensor from the memory.

FIELD OF THE DISCLOSURE

This disclosure relates generally to a serial interface connected device for environmental monitoring.

BACKGROUND

Typical environmental monitoring devices tend to be either stand-alone network attached appliances or simple, proprietary add-on sensors connected to such appliances. These typical environmental monitoring devices generally have high power consumption rates and are expensive. In addition, these typical environmental monitoring devices are often large and difficult to install.

Environmental monitoring systems are often used to measure moving fluid mass. HVAC, irrigation, fuel distribution, ventilation and cooling are some of the applications in which it is desirable to measure mass flow rate. Typical flow rate sensors use calibration or rely on precision components to maintain accuracy from unit to unit. These sensors typically consume a great deal of power and are expensive. Many such sensors lack sensitivity to low mass flow.

Accordingly, an improved environmental monitoring device would be desirable.

SUMMARY

In a particular embodiment, the disclosure is directed to a sensor pod including a housing, a temperature sensor, a humidity sensor, an airflow sensor, an external sensor interface, a processing circuitry located within the housing, a memory responsive to the processing circuitry, and a universal serial bus (USB) interface coupled to the processing circuitry. The temperature sensor, the humidity sensor, the airflow sensor, and the external sensor interface are responsive to the processing circuitry. The memory includes a static identification number. The USB interface is configured to provide access to measured data associated with the temperature sensor, the humidity sensor, the airflow sensor, and the external sensor interface. The measured data is associated with the static identification number.

In another embodiment, the disclosure is directed to a computer-implemented method of determining airflow including measuring a reference temperature, measuring a heater temperature associated with a heating element, determining a temperature difference between the reference temperature and the heater temperature, heating the heating element until the temperature difference reaches a first specified value and determining a cooling time period for the temperature difference to reach a second specified value.

In a further exemplary embodiment, the disclosure is directed to a sensor device including processing circuitry, at least one sensor coupled to the processing circuitry, a serial data interface coupled to the processing circuitry and memory responsive to the processing circuitry. The memory includes a static unique identification number. The serial data interface provides access to retrieve the static unique identification number and sensed data measured with the at least one sensor from the memory.

In an exemplary method, the disclosure is directed to a method of providing data including receiving a data request from a host device via a serial data interface, retrieving sensor data associated with at least one sensor, associating a static unique identification with the retrieved sensor data and providing the retrieved sensor data and the static unique identification to the host device via the serial data interface.

In another exemplary embodiment, the disclosure is directed to a method of providing notification of a sensor condition including requesting sensor data associated with at least one sensor from a peripheral device via a serial data interface, receiving the sensor data via the serial data interface, interpreting the sensor data associated with the at least one sensor and a static unique identification number to produce a condition result and sending a notification in response to the condition result. The sensor data comprising the static unique identification number to uniquely identify the peripheral device.

In a further embodiment, the disclosure is directed to a sensor device including a temperature sensor, a humidity sensor, an airflow sensor, processing circuitry responsive to the temperature sensor, the humidity sensor and the airflow sensor and a serial data interface coupled to the processing circuitry.

DETAILED DESCRIPTION OF THE DRAWINGS

The present disclosure relates to a device with integrated environmental sensors that measure temperature, relative humidity, airflow, and audio. The device may also include external expansion ports for connecting additional environmental sensors and general purpose sensors. The device generally collects data from its integrated sensors and external ports and delivers this data to a host device when requested by the host device via a serial data interface, such as a universal serial bus (USB) interface. Once this data is delivered to the host device, the host can display current environmental conditions to a user, display historical values of one or more sensors in a graphical display, archive the data, and/or notify the user when conditions violate user-specified conditions.

FIG. 1is a block diagram depicting an exemplary system for monitoring space or equipment134external to the device. A sensor device112connects to a network environmental management system126via a connection122, such as a serial data connection, for example, a USB connection. The sensor device112may include several sensors and an interface120. The interface120may communicate with a host interface124of the environmental management system126through the connection122. The environmental management system126may retrieve sensor data from the sensor device112and provide the sensor data to a user132or a storage system130through an interconnected network128. In this manner, the sensor device112may be used to monitor the environmental conditions and operations associated with a space or designated equipment134and provide data to a remote user132.

The sensor device112may include a plurality of sensors, such as the illustrated sensors114,116, and118. The sensors may, for example, include temperature sensors, humidity sensors, airflow sensors, audio sensors, and various external sensors such as door sensors and moisture sensors.

In addition, the sensor pod112may include a static unique identification number that may be stored and included with sensor data. In one particular embodiment, each sensor device receives a unique static identification at the time of manufacture. In another embodiment, a user may set the unique static identification. The unique static identification may be used to maintain data integrity. For example, labels, sensor value thresholds, and sensor value history associated with a given sensor device may be “re-associated” with the device when the device is disconnected, and a USB hub or USB extender cable is inserted before reconnecting to a host device. The unique static identification number may be included both on a label on the physical device and as the default label used for the device within a host or user application software, providing the end-user with a simple mechanism for correlating a device in the host or user application with a physical device. Software associated with this embodiment also supports “hot plugging” the device. When the device is detected by the USB subsystem, the host application automatically configures the device, generates default sensor thresholds and begins collecting and recording sensor data. The host system software may assume that the device should not be removed without user approval once connected, and may be optionally configured to generate both visual status and notifications in the form of SNMP trap, e-mail, HTTP Posts, FTP, and audio output to report the failure of the device, such as through a lost connection.

The sensor pod112may also include a display and audio speaker system. The sensor pod112may use the display or audio speaker system to indicate errors, failures, or threshold violating measurements.

In another exemplary embodiment, the host device, such as the environmental management system126may connect with other environmental management systems via wired and wireless communication methods. More than one sensor device may be coupled to a host device.

The other environmental management systems may associate sensor data with previous measurements based on the static unique identification number.FIG. 2depicts a sensor device200. In this exemplary embodiment, the sensor device200includes a humidity sensor202, a temperature206, an airflow sensor210, an audio sensor214, and an external sensor connection218. The sensors may be connected to processing circuitry222through connections204,208,212,216, and220, respectively. Digital sensors may be connected directly to the processing circuitry222. Alternately, analog sensors may utilize analog-to-digital converters. The processing circuitry222is coupled to an interface224and an optional display226. The interface224may be a serial data interface, such as a USB interface,

The processing circuitry222may interact with the sensors and provide data to a network environmental management system through the interface224. The circuitry222and sensors202,206,210,214, and218may also be powered from electricity supplied through the interface224. The circuitry222may associate a static unique identification number228that may be stored separately or together with the retrieved sensor data. If, for example, the USB address of the sensor device200were to change or the sensor device200were to be connected to a different USB host, the data may be correlated with previous data collected by the sensor unit200.

In addition to the integrated environmental sensors and expansion ports, a particular embodiment includes a display226such as status LEDs to indicate when an environmental condition has exceeded the user-specified threshold or when an error condition is detected. The embodiment may also include an audio transducer to generate an audible alert under programmatic control. The status LEDs implement a cycling “blink pattern”, using the combination of 4 sensor-type-specific LEDs (“Temp”, “Humidity”, “Airflow”, “Audio”) and an external sensor indicator LED (“External”) to provide a simple summary of error conditions associated with the device. In one exemplary embodiment, the summary may show appropriate sensor-type LED for a short period of time, for example 1 second, combined with the “External” LED when the error refers to an attached sensor as opposed to an integrated sensor. In one particular embodiment, the LEDs may be turned off for a short time (½ second), and the next error condition in the cycle is shown. When the last condition has been shown, the cycle returns to the first condition. When no errors are being reported, the LEDs may be off.

A particular implementation may support using distinctive audio tone and beep patterns to enable audio notification of alert conditions, including sensitivity to the severity of the problem being reported. For example, a “warning” level condition may blink the LEDs, an “error” level may provide a short, attention-grabbing BEEP, and a “failure” may provide a very urgent and annoying high pitched whistle. An exemplary display is illustrated byFIG. 3, which shows an external housing of an exemplary sensor device300. The housing includes LEDs302to form the display.

In a particular embodiment, the temperature sensor includes an integrated digital temperature sensor and an integrated analog temperature sensor. The device reads the temperature value from the digital temperature sensor via a digital serial interface. The device determines the temperature value from the analog temperature sensor by sampling the output voltage of the analog temperature sensor with, for example, a 12-bit analog-to-digital converter. The analog temperature sensor may be mounted on the outside surface of the device and the digital temperature sensor may be mounted inside the device. Multiple readings from each of the temperature sensors are taken and averaged to produce an averaged digital temperature reading and an averaged analog temperature reading. When a host requests environmental data, the recent average values of the digital temperature sensor and the analog temperature sensor are sent to the host. Software on the host device may manipulate these average values to provide temperature readings in degrees Fahrenheit and degrees Celsius. A particular embodiment, which operates with a peak power consumption of under 100 mA at 5V and typical power use, measures temperature accurately while reducing thermal contamination of the reading.

The device may include an integrated digital humidity sensor. Alternate variations of the device may have an analog humidity sensor in place of the digital humidity sensor. The device reads the humidity value from the digital humidity sensor via a digital serial interface. In one exemplary embodiment, the humidity sensor is mounted inside the device. Multiple readings from the humidity sensor may be taken and averaged to produce an averaged humidity reading.

In one particular embodiment, when the host requests the environmental data, the recent average values for the humidity reading, digital temperature sensor reading, and analog sensor reading are sent to the host. Software on the host device may manipulate the humidity reading, the digital temperature reading and the analog temperature reading to determine a relative humidity reading corresponding to the vapor pressure density of the air outside the device. The relative humidity value and the temperature values may also be used to calculate the current dew point value.

The dew point “sensor” may be a synthesized sensor using readings of the humidity sensor and a digital temperature sensor. Relative humidity is a function of both temperature and the amount of the water present, so a shift in relative humidity can result from adding or removing water in the environment, shifting temperature, or a combination of both. Dew point eliminates temperature-sensitivity of the measurement. A change in dew point implies a change in the amount of water present in the environment. In some situations, such as environmentally controlled spaces, raised equipment floors or manufacturing facilities, specific detection of a change in the mass of water vapor present is preferred over relative humidity measurement. An increase in dew point may indicate a water leak or a possible failure of part of the cooling system, such as a blocked condensation drain.

Accurate measurement of the temperature and humidity at the same location within the device, combined with an external temperature sensor, allows relative humidity of the air outside the device to be accurately measured without directly exposing the humidity sensor to the outside environment and without a forced airflow or other solution to assure that the humidity reading is not compromised by the self-heating of the device. The outside environment is subject to both mechanical stresses due to device handling or dropping, dust, contaminants, and other potentially damaging stresses.

FIGS. 4 and 5depict exemplary mass flow rate sensors. One of the applications of the mass flow sensor is to measure air flow rates. The circuit shown inFIG. 4is designed to enhance air flow rate measurement. Other embodiments can be constructed to measure rates of other flowing masses. The physical elements which make up the disclosed system include reference temperature sensor406, temperature sensor402, heater404, thermal coupling418between heater and temperature sensor, heater control circuit408, analog to digital converter410, time reference416, code store containing process parameters and values to convert the process output to accurate flow readings414, and processing element412.

The reference temperature sensor406is used in calculating a difference between the reference and the temperature sensor402coupled to the heater404. The converter410changes the format of the temperature sensors so the processing element412can access it. The physical layout of the components determines their thermal interaction. The reference sensor406is isolated or separated from the temperature sensor402associated with the heater404. The thermal association418of the temperature sensor402and the heater404through, for example, copper and the isolation of the heater404from the reference temperature sensor406form the basis of the thermal system.

As the mass flows across the physical components, some of the heat added by the process is removed. The reference temperature sensor406provides a baseline temperature of the mass so that the process can add an appropriate amount of heat for the measurement.

The mass flow sensor utilizes the consistent thermal mass, size and shape of the components and circuit by measuring the amount of time the components take to cool from a preset high temperature to a low temperature. The small geometries and low thermal mass make for a quick reacting sensor with low energy consumption to produce a temperature difference. Lower cost, less accurate components can be used in this mass flow sensor. The system has a high accuracy due to the ability of the processing element to calculate and save the difference between the temperature sensors prior to any airflow measurements.

One particular implementation is shown inFIG. 5with the heaters labeled R18and R19, the temperature sensor labeled U6, the reference temperature sensor labeled U5and the heater control circuit labeled Q1. The reference temperature sensor U5is thermally isolated from the temperature sensor U6and the heaters R18and R19through an absence of substrate and limited interconnects between the reference temperature sensor U5and the heaters R18and R19. Thin, low thermal conduction traces interconnect the areas to be thermally isolated. Copper planes are generally absent in isolated areas. Holes and voids may also be used as thermal barriers.

FIG. 6depicts an exemplary method to determine airflow rate. A reference temperature measurement is made, as shown at step602. A heater temperature measurement is made, as shown at step604. Referring toFIG. 4, the processing element412determines that the temperature difference between the reference temperature sensor406and the heated sensor402is below a preset amount, as shown at step606, and applies thermal energy to the heaters404through the heater control circuit408, as shown at step608. A minimum amount of energy needed to produce the desired temperature difference is applied. In high airflow situations, more energy is applied to the heater until a predetermined temperature difference is reached. This method uses low amounts of energy and has the effect of producing low thermal corruption. The energy is increased until the time when the predetermined temperature difference is reached.

Energy is removed and the temperature difference is monitored until a lower temperature difference is reached. To allow for the thermal inertia of the system, the point in time when the difference (minus any stored correction offsets) reaches this low temperature difference is the base time for the processing element to reference when deciding the time period for cooling.

The processing element, using the time reference, tracks the amount of time between crossing the last temperature threshold and when the temperature difference reaches a lower temperature threshold, as shown at step610. This time is empirically correlated to mass flow, as shown at step612. The relationship is stored in the parameters and code store element and referenced by the processing element for reporting the mass flow value. This process is done again as needed to measure a continuum of mass flows.

The temperature decays exponentially, as shown inFIG. 7, but the cooling varies significantly with mass flow across the components. The difference in cooling time is used to calculate the mass flow. It has been observed that the log (time) vs. log (massflow) exhibits a linear relationship.

Because the heater is turned off for the measurement period, the circuit is insensitive to heater voltage and component tolerances. The granularity of the readings is expanded towards the low end, providing greater sensitivity for lower mass flow measurements.

The zero mass flow point can be established to avoid factory calibration. When components used are consistent (not high tolerance, but same components), the cost of production is reduced because the calibration step is removed. The illustrated mass flow sensor uses lower power in low airflow, is easy to produce and has low sensitivity to power supply and other component tolerances. The sensor uses a low level of average power due to the exponential nature of cooling has greater sensitivity at low airflow. It facilitates removal of offsets due to component tolerances and only consumes power when reading mass flow rates. The sensor is also quick reacting.

In a particular embodiment, when a USB host requests environmental data, the most recent airflow reading is sent to the USB host. Software on the USB host device manipulates this value to provide airflow readings in feet per minute and meters per minute.

FIG. 8illustrates an exemplary method for providing data. As shown at step802, the sensor pod receives a request for data through the USB interface. The sensor pod accesses the sensor, as shown at step804. The sensors may be accessed as a result of the data request or accessed periodically. In some cases, the sensors may be accessed periodically and an average determined. The data is prepared, as shown at step806, and a unique static identification is incorporated with the data, as shown at step808. The unique static identification may be used to associate the data with other data from the device in the event that the USB address or host device change. The data is sent to a host device through the USB interface, as shown at step810.

FIG. 9depicts an exemplary method for providing data. A host device requests data associated with a sensor from a peripheral device through a USB interface, as shown at step902. The host device receives the data including a unique static identification number, as shown at step904. The data is interpreted in accordance with conditional logic associated with the unique identification number and the sensor, as shown at step906. The conditional logic may, for example, include comparison with threshold values. A notification may be sent in response to a result of the interpretation, as shown at step908. The notification may be sent in an email, text message, post message, or page, among other methods. The data may also be sent to storage, as shown at step910.

A particular embodiment includes an integrated audio sensor to measure audio level in the vicinity of the USB device. The audio sensor includes a microphone, analog filtering and amplification, an analog-to-digital converter and software-based digital filtering. The resulting data generated for the audio sensor is a relative measurement of the peak amount of high-frequency (1–2 KHz or higher) audio energy currently found in the environment. In most environments, sound levels in these frequency ranges are relatively low unless an audio alarm is present, such as a fire alarm, or the alarm “beeps” of a UPS, cooling system, or other electronic device, is present. High frequency detection provides an effective mechanism for detecting such alarms, while not intruding on the privacy of any persons present, since the audio samples do not exit the device.

A particular embodiment includes four expansion ports for the purpose of connecting additional environmental sensors, general purpose analog sensors, general purpose digital sensors, analog measurement devices, digital measurement devices, dry-contact inputs, and dry-contact outputs.FIG. 10depicts an exemplary device1002with expansion slots1004located on the bottom of the sensor pod.

Each of the expansion connectors may include a bi-directional digital serial interface, 5V power, 3.3V power, an analog input, and a ground reference. A particular embodiment implements this connector using an 8-pin DIN connector.

The voltage of an exemplary analog input on each expansion port is sampled via an analog-to-digital converter. These samples are accumulated and used to determine an average DC reading and an average RMS AC reading. When the USB host requests the expansion port data, the most recent average DC reading and the most recent average AC reading are sent to the USB host. Software on the USB host device may manipulate these values according to the type of sensor or measurement device connected to the port to provide a more meaningful interpretation of the data to a user.

The digital serial interface on each expansion port is used for digital input and output between a device and the sensor or monitoring device connected to the external port. When a USB host requests the expansion port data from the device, the most recent digital value from the expansion port is sent to the USB host. The digital interface on the expansion port may also allow the USB host to control the state of an output device such as a dry-contact connected to the expansion port of the device.

A particular embodiment of the device utilizes a Cypress EZ-USB FX processor. This processor includes an on-chip USB interface. This embodiment also utilizes a 128 Kbyte static RAM for program and data storage and a 128 Kbit EEPROM for non-volatile program and data storage.

In one particular embodiment, the device may be attached to a host device or be detached and located remotely from the host device.FIG. 11depicts a side view of an exemplary sensor pod or device1102. Because this embodiment utilizes a USB interface, it allows the device to function when connected to any device that includes a standard USB host interface. For instance, the same device can be connected either to a standard PC or to a proprietary data collection instrument.

The device includes a USB connector1106, such as a USB Type-B connector for connecting the device to the USB host or USB hubs via standard USB cables. The embodiment draws its power from the USB interface, allowing the device to operate with a single cable attachment. The embodiment includes docking hardware1104and a card-edge connector1108for use as an alternate USB interface connection and allowing the device to be docked to a proprietary data collection instrument. When the device is docked in this manner, the USB Type-B connector is not accessible, ensuring that only one of the two connections is used at any time.

FIGS. 12 and 13depict an exemplary host device for attaching the device.FIG. 12illustrates a cross-section of an exemplary host unit1202. The host unit1202has a base unit printed circuit assembly (PCA)1204coupled to an interposer PCA1208via connector1206, such as a ribbon cable. The interposer PCA1208includes mating connectors1212for PCA card edges. The card-edge connectors1212may include a positive data connection, a negative data connection, a positive power connection, and a ground connection. The card-edge connectors1212may also include a shielded ground connection.

In addition, the host unit1202may include a sliding mechanism or docking pin retainer1210. Docking pins may be inserted into the docking pin retainer1210. The retainer may then be adjusted by, for example, using a screw to lock the docking pins in place. The docking pins maybe released by re-adjusting the docking pin retainer1210.

FIG. 13illustrates another example of a host unit1302. A front view and side view are shown. To dock a peripheral device, the docking pins are inserted into access points1310on a slider bar1312. The card-edge connectors1318contact the card-edge on the peripheral device. The slider bar1312may then be adjusted using, for example, a screw1304.

A host unit may permit the connection of more than one device. In this example, two devices may be connected. Two pin access points1310and a card-edge connector1318is provided for each device.

When the peripheral devices are disconnected, a wire may be run from a USB connector on the base unit to a USB connector on the peripheral device. The peripheral device may, for example, also have a Type B USB connector. Wires may be provided with various connectors such as USB Type A or USB Type B to connect with connectors on the peripheral device.

The peripheral devices may have two connectors. In the exemplary embodiment shown inFIG. 11, the side is shown having a USB type B connector, a card-edge connector, and docking pins. The card-edge fingers shown on the device ofFIG. 11may be used for connection and communication using USB protocols during docked operation. When pods are docked, the USB type B connector is not accessible.

Docking pins are located on the same side as the USB port and card-edge connector and are used for the mechanical coupling of the peripheral and base unit. This location of the docking pins prevents the user from incorrectly configuring the system by incorrectly connecting a USB cable to the device while docked, and protects the connector from contamination when no cable is present.

The USB type B connector may be used for tethered operation using a standard USB Cable. When pods are provided separately, an overlay, such as a label, may cover the card-edge fingers and may leave the USB type B connector uncovered. As the connector is recessed behind the plane of the metal enclosure, an end-user can also be supplied with a label for covering the connector when using the docked pod in a tethered configuration.

Because the USB type B and card-edge connectors are located on the docking side of the device, only one of the connections may be used at a time. If the USB connectors are coupled in parallel when connecting with the circuitry of the peripheral device, USB signals go to both connectors on the pod.

FIG. 14shows the docking pins1408connected to the peripheral devices1404and1406and sliding into access points on the host unit1402. The host unit1402includes a sliding retaining mechanism. Access points or keyholes in the slider slide over docking pins, locking peripheral devices1404and1406onto the base unit. The dimensions may be tailored so the pods are tightly coupled, thereby reducing problems with vibration or audible rattling of the assembly.

In one example, turning a screw1414moves the slider position to lock peripherals1404and1406into place, thereby preventing an accidental disconnection of the devices and providing a secure connection for the electrical and data signals. The screw1414may have a retainer ring on the inside to protect against the screw being removed from the chassis. Since the screw's position cannot move, the slider is forced to move as the screw is turned, allowing enough force to be used so the docked peripherals are rigidly attached, and reducing vibration that may loosen the docked pods.FIG. 15depicts the peripheral units coupled to the base unit.

In one particular embodiment of the system depicted inFIGS. 12 through 15, a Beak board is provided with card-edge connectors to connect to docked pods, allowing propagation of the data and power signals from the header of a ribbon cable to the docked pods through the dual connectors. A ribbon cable from the Beak to Main board may be designed with symmetric signals so the cable can be oriented either direction (pin1to pin1or pin1to pin10), thereby reducing assembly errors when connecting the cable. The flexible design allows for “blanks” to be put into place when both peripheral devices are not attached. Blanks may be used in place of a camera for a camera-less unit, a sensor pod for a sensor-less unit, or in place of a sensor pod and a camera for “monolith” product that uses only external tethered cameras and sensor pods. Optionally, the design allows for the placement of a cover or the manufacturing-time option to remove the beak, slider, and ribbon cables, and to cover the remaining openings with a label, allowing for a unit to be produced that does not support docking without additional or alternate manufactured parts.

The system design also allows for a large single peripheral device to be implemented (a single device utilizing the full height of the unit, and either of the USB interface or the card-edge connector). Since both peripheral devices in the exemplary utilization shown inFIG. 14are secured using the same retaining mechanism, the large single peripheral device can use the same mechanism.

In one embodiment, when a sensor device or peripheral device is connected to a host, the host is able to retrieve identifying information from the device. The host transfers program code into the device and the device begins execution of the program code. This programming function allows the host to update the program code inside the sensor device.