Patent Publication Number: US-9852594-B2

Title: Electronic apparatus and method for determining states of door thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Korean Patent Application No. 10-2015-0172990, filed on Dec. 7, 2015, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Apparatuses and methods consistent with the embodiments relate to an electronic apparatus and a method of determining states of a door thereof, and more particularly, to an electronic apparatus capable of determining states of a door, to which the electronic apparatus is attached, by sensing an acceleration and an angular speed, and a method of determining the states of the door thereof. 
     2. Description of the Related Art 
     The recent development of electronic technology has increased demands for technology that determines states of a thing and transmits the determined states to a user or a network such as a cloud server. 
     Existing door sensors determine states of a door by using a magnet, infrared (IR), or laser. Therefore, the existing door sensors have problems of limited sensing ranges and use scenarios. 
     The existing door sensors may frequently sense merely opening and closing of the door. Also, even when a door sensor is installed, the door sensor may be physically fixed to a door by using screws or the like. 
     There exist attempts to increase a use scenario by attaching a camera or the like, but there are problems of increasing electric power consumption and dropping a door sensor due to shocks occurring when opening and closing a door due to weight of the door sensor. 
     SUMMARY 
     Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the embodiments. 
     Exemplary embodiments overcome the above disadvantages and other disadvantages not described above. Also, the embodiments are not required to overcome the disadvantages described above, and an exemplary embodiment of the may not overcome any of the problems described above. 
     The embodiments provide an electronic apparatus capable of solving an inconvenience of an existing door sensor and determining states of a door based on sensed acceleration and angular speed, and a method of determining states of a door thereof. 
     According to an aspect, an electronic apparatus attached onto a door, includes a sensor configured to measure an acceleration and an angular speed of the electronic apparatus, a processor configured to sense an arrangement or arrangement form between the door and a doorframe to which the door is fixed, by using the measured acceleration and angular speed and determine whether the door is opened or closed, according to the sensed arrangement or arrangement form, and a communicator configured to transmit the determined state of the door to an external apparatus. 
     According to another aspect, a method of determining a door state of an electronic apparatus attachable onto a door, includes measuring an acceleration and an angular speed of the electronic apparatus, sensing an arrangement form between a doorframe to which the door is fixed and the door, by using the measured acceleration and angular speed, determining whether the door is opened or closed, according to the sensed arrangement form, and transmitting the determined state of the door to an external apparatus. 
     According to an aspect, a non-transitory computer readable recording medium storing a method of determining a door state of an electronic apparatus attachable onto a door, the method including measuring an acceleration and an angular speed of the electronic apparatus, sensing an arrangement between a doorframe to which the door is fixed and the door, by using the acceleration and angular speed, determining a door state as to whether the door one of is opened and closed, according to the sensed arrangement and transmitting the state of the door to an external apparatus. 
     According to an aspect, a method of determining a state of a door relative to a door frame, the method including sensing an acceleration and an angular speed of the door, determining the state as open when change in the acceleration and change in the angular speed is sensed, determining the state as closed when change in the acceleration is sensed and no change in angular speed is sensed and transmitting the state of the door to an external apparatus. 
     According to various exemplary embodiments, various types of door operations may be sensed by using sensed acceleration and angular speed. Also, a door may be simply installed, and an operation of the door may be sensed with a small amount of electric power. 
     Additional and/or other aspects and advantages will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects will be more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  is a concept view illustrating a concept of an electronic apparatus according to an exemplary embodiment; 
         FIG. 2  is a block diagram of a schematic configuration of an electronic apparatus according to an exemplary embodiment; 
         FIG. 3  is a block diagram of a detailed configuration of an electronic apparatus according to an exemplary embodiment; 
         FIG. 4  is a graph illustrating data collected by a gyro sensor of an electronic apparatus according to an exemplary embodiment; 
         FIG. 5  is a graph illustrating data collected by an acceleration sensor of an electronic apparatus according to an exemplary embodiment; 
         FIG. 6  is a graph illustrating a result of sensing vibrations in an electronic apparatus according to an exemplary embodiment; and 
         FIGS. 7 and 8  are flowcharts of methods of determining door states of an electronic apparatus according to various exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below by referring to the figures. 
     Certain exemplary embodiments will now be described in greater detail with reference to the accompanying drawings. 
     In the following description, the same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding. Thus, it is apparent that the exemplary embodiments may be carried out without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the embodiments with unnecessary detail. Also, terminology that will be described hereinafter is defined in consideration of functions in the embodiments and may be changed according to intentions, customs, or the like of users or operators. Therefore, the definition of the terminology may be given based on overall contents of the present specification. 
     Also, the terms “first”, “second”, etc. may be used to describe diverse components, but the components are not limited by the terms. The terms are merely used to distinguish one component from the others. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items. 
     The terminology used herein is for the purpose of describing particular embodiments merely and is not intended to be limiting of example embodiments. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “includes” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
       FIG. 1  is a view illustrating an electronic apparatus  100  according to an exemplary embodiment. Referring to  FIG. 1 , the electronic apparatus  100  may operate with being attached onto a door. Also, the electronic apparatus  100  may determine states of the door by using acceleration and angular speed sensed in response to motions of the door. The electronic apparatus  100  may also transmit the sensed states of the door to an external apparatus  200 . 
     For example, the external apparatus  200  may be realized as a cloud server, a management server, a home network hub, a wearable device, a mobile device, or the like. The electronic apparatus  100  and the external apparatus  200  may be connected to each other through a network to form an Internet of Things (IoT) environment. In detail, the electronic apparatus  100  and the external apparatus  200  may communicate with each other according to various methods such as Zigbee, Z-Wave, WFi, WiFi Direct, Bluetooth, and the like. 
     The electronic apparatus  100  is illustrated as being attached onto a pivotable hinged door in the exemplary embodiment of  FIG. 1 , but the types of door onto which the electronic apparatus  100  is attached so as to determine states are not limited thereto. For example, the electronic apparatus  100  may be attached onto various types of doors such as a revolving door, a sliding door, an automatic door, a window, a drawer, and the like. 
     The electronic apparatus  100  according to the exemplary embodiment may be made small, and thus is simply installed and consumes a small amount of electric power. For example, the electronic apparatus  100  may embody an acceleration sensor and a gyro sensor in one chip. Also, the electronic apparatus  100  may determine states of the door by using a Micro Controller Unit (MCU) of a communicator  120  without additionally including a processor  130 . 
       FIG. 2  is a block diagram of a schematic configuration of the electronic apparatus  100 , according to an exemplary embodiment. Referring to  FIG. 2 , the electronic apparatus  100  may include a sensor  110 , the communicator  120 , and the processor  130 . 
     The sensor  110  may measure acceleration and angular speed of the electronic apparatus  100 . For example, the sensor  110  may include an acceleration sensor and a gyro sensor. The sensor  110  may also be realized as a type constituted as one chip into which the acceleration sensor and the gyro sensor are integrated. Since the sensor  110  measures the acceleration and the angular speed of the electronic apparatus  100  attached to the door, the electronic apparatus  100  may sense a position change of the door, a shock applied onto the door, and the like. 
     The communicator  120  may transmit the determine states of the door to the external apparatus  200 . For example, the external apparatus  200  may be realized as a cloud server or the like. Also, the communicator  120  may receive a state request signal from the external apparatus  200 . 
     The processor  130  may determine the states of the door, onto which the electronic apparatus  100  is attached, by using the acceleration and angular speed measured by the sensor  110 . The processor  130  may be realized as an additional chip or the MCU embedded in the communicator  120  may perform an operation of the processor  130 . 
     In detail, the processor  130  may sense an arrangement or arrangement form between a doorframe to which the door is fixed and the door, by using the acceleration and the angular speed measured by the sensor  110 . Also, the processor  130  may determine whether the door is opened and closed, according to the sensed arrangement form. 
     For example, if the door is a door that is pivotable based on an axis of a doorframe, the processor  130  may determine the arrangement form based on the measured angular speed. The processor  130  may also compensate for the angular speed by using the measured acceleration. Since an angle is acquired according to a method of integrating the angular speed with respect to time, errors gradually increase if the angular speed is not compensated for. Therefore, the processor  130  may compensate for an error value of the angle by using an acceleration value. 
     As another example, if the door is a door that is movable back and forth in a straight line direction based on the doorframe, the processor  130  may determine the arrangement form based on the measured acceleration. Also, the processor  130  may determine a direction toward which a sliding door moves, by using the gyro sensor. 
     As another example, if the door is a window, the processor  130  may determine states such as vibrations and the like occurring due to an environment such as a knock, wind, or the like, by using a value measured by the acceleration sensor. 
     If it is determined that the door is in a closed state, the processor  130  may determine whether a state of the door is changed, by using the measured acceleration. For example, if an angular speed change is sensed in the sensor  110  after the door is determined as being in the closed state, the processor  130  may determine that the door is changed into an opened state. 
     As another example, if there is no angular speed change after the door is determined as being in the closed state but an angular speed change is sensed by the sensor  110 , the processor  130  may determine a detailed state of the door according to an angular speed change pattern. The processor  130  may determine the detailed state of the door by using at least one selected from an intensity, a cycle, the number of acceleration changes. 
     If the detailed state of the door is determined as a knock or an external intrusion state, the processor  130  may control the communicator  120  to notify the external apparatus  200  of a state of the door. If the external apparatus  200  is realized as a wearable device, a mobile device, or the like carried by the user, the processor  130  may notify the user that a particular state occurs. 
     Also, the processor  130  may control the communicator  120  to transmit the state of the door and a control command that enables the external apparatus  200  to perform an operation corresponding to the state of the door. For example, if the state of the door is determined as the external intrusion state, the processor  130  may notify the external apparatus  200  of the external intrusion state. Simultaneously with this, the processor  130  may control the communicator  120  to transmit a control command that enables the external apparatus  200  to automatically transmit a message for requesting a mobilization to a police or a security company. 
     In addition, if the determined state of the door is changed or a signal for requesting state information is received from the external apparatus  200 , the processor  130  may control the communicator  120  to transmit a current state of the door to the external apparatus  200 . 
     According to the electronic apparatus  100  according to various exemplary embodiments as described above, various types of scenarios may be sensed with respect to various types of doors. 
       FIG. 3  is a block diagram of a detailed configuration of the electronic apparatus  100  according to an exemplary embodiment. Referring to  FIG. 3 , the electronic apparatus  100  may include the sensor  110 , the communicator  120 , the processor  130 , and a power unit  140 . However, the electronic apparatus  100  according to the exemplary embodiment is not limited to an inclusion of all of the above-described elements. Also, the electronic apparatus  100  may additionally include elements that are not shown in the exemplary embodiment of  FIG. 3 . For example, the electronic apparatus  100  may further include a storage unit (not shown) capable of storing acceleration and angular speed values sensed by the sensor  110 . 
     The sensor  110  may measure acceleration and angular speed in response to a type of a door to which the electronic apparatus  100  is attached. An existing door sensor includes two parts and thus mainly uses a magnet method of fixing one part to the door and the other part to a doorframe. However, the electronic apparatus  100  according to the exemplary embodiment may determine a state of the door through the sensor  110  realized as one part and thus may be simply installed. 
     The sensor  110  may include an acceleration sensor for measuring acceleration and a gyro sensor for measuring an angular speed. The sensor  110  may embody the acceleration sensor and the gyro sensor as one chip. The electronic apparatus  100  may sense a start position and a current position of a motion and measure position changes by using six axes of the acceleration sensor and the gyro sensor. 
     The acceleration sensor may sense a gravity direction. Also, the acceleration sensor may sense a gradient in an immovable state. The acceleration sensor senses changes in a speed with respect to a unit time. The acceleration sensor may be realized as three axes. If the acceleration sensor is realized as a triaxial acceleration sensor, the acceleration sensor includes X, Y, and Z acceleration sensors that are disposed in different directions to be orthogonal to one another. 
     The acceleration sensor respectively converts output values of the X, Y, and Z acceleration sensors into digital values and provides the digital values for a preprocessor. Here, the preprocessor may include a chopping circuit, an amplifier circuit, a filter, an analog-to-digital converter (ADC), and the like. Therefore, the preprocessor chops, amplifies, and filters an electrical signal output from the triaxial acceleration sensor, and converts the electrical signal into a digital voltage value. 
     The gyro sensor is an element that senses angular speed by sensing changes in a preset direction of the electronic apparatus  100  for a unit time. The gyro sensor may be a gyroscope having three axes. The gyro sensor may analyze an angle through a definite integral value of a sensed angular speed. However, if merely the gyro sensor is used, an accurate angle may be determined due to an accumulation of errors occurring in integral calculations. 
     The electronic apparatus  100  according to the exemplary embodiment may compensate for angular speed by using the measured acceleration. For example, the processor  130  may compensate for the angular speed by using a complementary filter or a Kalman filter. In other words, since the processor  130  includes the acceleration sensor and the gyro sensor, the sensor  110  may measure an accurate angle of the door. 
     According to another exemplary embodiment, if the door is determined as a closed state and then maintains the closed state until a preset time elapses, the sensor  110  may delete an accumulative error, which may occur, by re-calibrating or resetting the gyro sensor. 
     The sensor  110  may additionally include a geomagnetic sensor besides the acceleration sensor and the gyro sensor. The geomagnetic sensor is a sensor capable of detecting azimuth by detecting a flow of a magnetic field. The geomagnetic sensor may detect azimuth coordinates of the electronic apparatus  100  and detect a direction in which the electronic apparatus  100 , based on the azimuth coordinates. 
     The geomagnetic sensor detects geomagnetism according to a method of measuring a voltage value induced by the geomagnetism by using a flux-gate or the like. The geomagnetic sensor may be realized as two axes or three axes. In this case, since a geomagnetic output value calculated by each axial geomagnetic sensor depends on a surrounding magnetic field size, the geomagnetic sensor normally performs normalization of mapping the geomagnetic output value in a preset range (e.g., within a range between −1 and 1). The normalization is performed by using a normalization factor such as a scale value or an offset value. In order to calculate the normalization factor, output values of the geomagnetic sensor may be calculated with rotating the geomagnetic sensor several times, and then a maximum value and a minimum value of the output values may be detected. A value normalized by the normalization factor is used for an azimuth correction job. 
     The communicator  120  may perform transmission and reception with the external apparatus  200 . In detail, the communicator  120  may transmit the state of the door determined by the processor  130  to the external apparatus  200 . The communicator  120  may also receive a state request command from the external apparatus  200 . 
     For example, the communicator  120  may be realized as a module performing a Zigbee or Z-Wave communication. Zigbee and Z-Wave are short-range wireless communication methods for remote monitoring and controlling. Zigbee has a higher data speed and a narrower operation range than Z-wave. The communicator  120  may communicate with the external apparatus  200  by using a Zigbee or Z-Wave method according to a distance from the external apparatus  200  and the like. 
     Zigbee is a wireless standard complying with a Personal Area Network (PAN) wireless standard of Institute of Electrical and Electronics Engineers (IEEE) 802.15.4. Zigbee mainly operates in a band of 2.4 GHz and uses an Offset Quadrature Phase-Shift Keying (OQPSK) modulation. Also, Zigbee has a data speed of about 250 kbit/s and an operation range of about 10 m. 
     Z-Wave operates in a band of 908.42 MHz and uses a Gaussian Frequency-Shift Keying (GFSK) modulation. Also, Z-Wave has a data speed between about 9.6 kbit/s and about 40 kbit/s and an operation range of about 30 m. 
     Also, the communicator  120  may communicate with the external apparatus  200  by using various types of wireless communication methods such as WiFi, WiFi Direct, Bluetooth, Bluetooth Low Energy (BLE), and the like. 
     The power unit  140  may supply other elements of the electronic apparatus  100  with electric power under control of the processor  130 . 
     If acceleration and angular speed changes measured for a preset time or more are in a preset range, the processor  130  may control the power unit  140  to supply electric power to merely the minimum number of elements maintaining an operation of the electronic apparatus  100 . In other words, the processor  130  may change an operation mode of the electronic apparatus  100  into a standby mode. For example, in the standby mode, the processor  130  may control the power unit  140  to stop supplying power to the communicator  120 . 
     If an acceleration change higher than or equal to a preset value is sensed after the operation mode is changed into the standby mode, the processor  130  may control the power unit  140  to supply power to all elements of the electronic apparatus  100 . In other words, the processor  130  may change the operation mode of the electronic apparatus  100  from the standby mode into an operating mode. 
       FIG. 4  is a graph illustrating data collected by a gyro sensor of the electronic apparatus  100 , according to an exemplary embodiment. In the exemplary embodiment of  FIG. 4 , the electronic apparatus  100  is attached onto a door that is opened and closed according to X direction pivoting. 
     For example, if the door pivots in a closed state, the sensor  110  may sense an angular speed change as at a peak marked with number {circle around (1)}. The processor  130  may determine that an arrangement or arrangement form between the door and a doorframe is changed, by using angular speed value sensed by the sensor  110 . In other words, the processor  130  may determine that the door is in an opened state when the peak marked with the number {circle around (1)} is generated. 
     On the contrary, if the door pivots in an opposite direction, the sensor  110  may sense angular speed change as at a peak marked with number {circle around (2)}. The processor  130  may determine that the door pivots in the opposite direction. In other words, the processor  130  may determine that the door is in a closed state when the peak marked with the number {circle around (2)} is generated. 
       FIG. 5  is a graph illustrating data collected by an acceleration sensor of the electronic apparatus  100 , according to an exemplary embodiment. In the exemplary embodiment of  FIG. 5 , the electronic apparatus  100  is attached onto a door where an acceleration change occurs in a Y direction. Also, in the exemplary embodiment of  FIG. 5 , the door may be in a closed state. 
     If the door is in the closed state, and an acceleration change is measured as at a peak marked with number {circle around (3)} of  FIG. 5 , the processor  130  may determine a detailed state of the door according to a measured acceleration change pattern. 
     According to an exemplary embodiment, the processor  130  may determine one of a knock state, a vibration state caused by an environment such as wind and the like, and an external intrusion attempt state according to the measured acceleration change pattern. The processor  130  may determine states based on an intensity, a cycle, and the number of acceleration changes. 
     For example, when the door is in a vibration state caused by an environment such as wind or the like, an intensity of an acceleration change sensed by the sensor  110  is lowest. Therefore, if an acceleration change is sensed as being lower than or equal to a preset intensity, the processor  130  may determine a state of the door as the vibration state caused by the environment. 
     As another example, if periodic acceleration changes between two times and three times are sensed as intermediate level intensities, the processor  130  may determine the state of the door as a knock state. 
     As another example, if the sensor  110  senses an acceleration change higher than or equal to a preset intensity or senses a periodic acceleration change for a preset time or more, the processor  130  may determine the state of the door as an external intrusion state. 
     The intensity, the cycle, and the number of the acceleration changes that are determination criterions of the processor  130  may be differently set according to specifications of a door onto which the electronic apparatus  100  is installed. 
     According to an exemplary embodiment, if acceleration and angular speed changes measured for a preset time or more are in a preset range, the processor  130  may change an operation mode of the electronic apparatus  100  into a standby mode. In detail, if there is the small number of changes in data measured by the sensor  110  for a preset time or more, the processor  130  may change a calculation block of the communicator  120  or the processor into a standby mode. 
     Also, if the sensor  110  senses acceleration or angular speed change higher than or equal to a preset value, the processor  130  may change the operation mode of the electronic apparatus  100  from the standby mode into an operating mode. In detail, when a change in data measured by the sensor  110  is higher than or equal to a preset value, the processor  130  may change the calculation block of the communicator  120  or the processor  130 , which is changed into the standby mode, into the operating mode. 
       FIG. 6  is a graph illustrating a result of sensing external vibrations in the electronic apparatus  100 , according to an exemplary embodiment.  FIG. 6  illustrates a test result of sensing vibrations occurring in an air cleaner that rarely vibrates. 
     On a vertical axis of  FIG. 6 , an acceleration (a gravity acceleration) of 1G as an acceleration value is written in unit of 8,192. As shown in  FIG. 6 , the sensor  110  according to an exemplary embodiment may measure an acceleration change between about 1/20 and 1/30 of the gravity acceleration. The processor  130  may set a preset value for changing a standby mode into an operating mode from a very low acceleration value. 
     Also, the processor  130  takes merely a time between 5 μs and 110 μs to change an operation mode of the electronic apparatus  100  as shown in Table 1 below. Therefore, the change into the standby mode does not affect a performance of a sensing operation of the processor  130 . 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Parameter 
                 Test Condition 
                 Min 
                 Typ 
                 Max 
                 Unit 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 System wake 
                 From wake up event to 
                 — 
                 110 
                 — 
                 μs 
               
               
                 time from 
                 first ARM ® Cortex ™-M3 
               
               
                 deep sleep 
                 instruction running from 6 
               
               
                   
                 MHz internal RC clock 
               
               
                   
                 includes supply ramp time 
               
               
                   
                 and oscillator startup time 
               
               
                 Shutdown 
                 From last ARM ® Cortex ™- 
                 — 
                 5 
                 — 
                 μs 
               
               
                 time going 
                 M3 instruction to deep 
               
               
                 into deep 
                 sleep mode 
               
               
                 sleep 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, a deep sleep mode corresponds to a standby mode, and a wake up event corresponds to a change into an operating mode. According to the test result shown in  FIG. 1 , the electronic apparatus  100  takes a time of 5 μs to change into the standby mode and takes a time of 110 μs to change into the operating mode. 
     The electronic apparatus  100  according to an exemplary embodiment may be changed into the standby mode so as to reduce an amount of consumed electricity power. Table 2 below shows an amount of consumed current if the electronic apparatus  100  is changed into the standby mode. An amount of current consumed in the standby mode may be merely several μA. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Parameter 
                 Test Condition 
                 Min 
                 Typ 
                 Max 
                 Unit 
               
               
                   
               
             
            
               
                 Regulator input voltage 
                   
                 2.1 
                 — 
                 3.6 
                 V 
               
               
                 (VDD_PADS) 
               
               
                 Power supply range 
                 Regulator output or external 
                 1.7 
                 1.8 
                 1.9 
                 V 
               
               
                 (VDD_MEM) 
                 input 
               
               
                 Power supply range 
                 Regulator output 
                 1.18  
                 1.25 
                 1.32  
                 V 
               
               
                 (VDD_CORE) 
               
            
           
           
               
            
               
                 Deep Sleep Current 
               
            
           
           
               
               
               
               
               
               
            
               
                 Quiescent current, internal 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 0.9 
                 — 
                 μA 
               
               
                 oscillator disable, 4 kB 
               
               
                 RAM retained 
               
               
                   
                 +25°, VDD_PADS = 3.6 V 
                 — 
                 1.0 
                 — 
                 μA 
               
               
                   
                 +85°, VDD_PADS = 3.6 V 
                 — 
                 2.2 
                 — 
                 μA 
               
               
                 Quiescent current, 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 1.2 
                 — 
                 μA 
               
               
                 including internal RC 
               
               
                 oscillator, 4 kB RAM 
               
               
                 retained 
               
               
                   
                 25°, VDD_PADS = 3.6 V 
                 — 
                 1.25 
                 — 
                 μA 
               
               
                   
                 85°, VDD_PADS = 3.6 V 
                 — 
                 2.5 
                 — 
                 μA 
               
               
                 Quiescent current, 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 1.3 
                   
                 μA 
               
               
                 including 32.768 kHz 
               
               
                 oscillator, 4 kB RAM 
               
               
                 retained 
               
               
                   
                 25°, VDD_PADS = 3.6 V 
                 — 
                 1.6 
                 — 
                 μA 
               
               
                   
                 85°, VDD_PADS = 3.6 V 
                 — 
                 2.9 
                 — 
                 μA 
               
               
                 Quiescent current, 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 1.6 
                 — 
                 μA 
               
               
                 including RC oscillator 
               
               
                 and 32.768 kHz oscillator, 
               
               
                 4 kB RAM retained 
               
               
                   
                 25°, VDD_PADS = 3.6 V 
                 — 
                 1.9 
                 — 
                 μA 
               
               
                   
                 85°, VDD_PADS = 3.6 V 
                 — 
                 3.2 
                 — 
                 μA 
               
               
                 Additional quiescent 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 0.007 
                 — 
                 μA 
               
               
                 current per 4 kB block of 
               
               
                 RAM retained 
               
               
                   
                 25°, VDD_PADS = 3.6 V 
                 — 
                 0.067 
                   
                 μA 
               
               
                   
                 85°, VDD_PADS = 3.6 V 
                 — 
                 0.76 
                 — 
                 μA 
               
               
                 Additional quiescent 
                 −40°, VDD_PADS = 3.6 V 
                 — 
                 0.57 
                 — 
                 μA 
               
               
                 current when retained 
               
               
                 RAM exceeds 32 kB 
               
               
                   
                 25°, VDD_PADS = 3.6 V 
                 — 
                 0.67 
                 — 
                 μA 
               
               
                   
                 85°, VDD_PADS = 3.6 V 
                 — 
                 2.0 
                 — 
                 μA 
               
               
                 Simulated deep sleep 
                 with no debugger activity 
                 — 
                 500 
                 — 
                 μA 
               
               
                 (debug mode) current 
               
               
                   
               
            
           
         
       
     
     If a camera and the like are attached to improve an existing sensor, a current is consumed on a level of 300 mA, and thus it is inappropriate to use a miniaturized coin battery (225 mAh capacity). However, the electronic apparatus  100  according to an exemplary embodiment may determine a state of a door by using data sensed by the sensor  110  and thus may operate even at a capacity of a miniaturized coin battery. Also, if the electronic apparatus  100  is changed into a standby mode, an amount of consumed current is further reduced. 
     According to this characteristic, the electronic apparatus  100  according to an exemplary embodiment may reduce an amount of consumed electricity power and may additionally reduce a space restriction and a size. 
       FIG. 7  is a flowchart of a method of determining a door state of the electronic apparatus  100 , according to an exemplary embodiment. 
     Referring to  FIG. 7 , in operation S 710 , the electronic apparatus  100  may measure acceleration and angular speed. The electronic apparatus  100  may check acceleration and angular speed of a door onto which the electronic apparatus  100  is attached, by measuring acceleration and angular speed thereof. For this, the electronic apparatus  100  may include an acceleration sensor and a gyro sensor. 
     In operation S 720 , the electronic apparatus  100  may determine a state of the door by using the measured acceleration and angular speed. In detail, the electronic apparatus  100  may sense an arrangement form between the door and a doorframe to which the door is fixed, by using the measured acceleration and angular speed. This is because a position change of the electronic apparatus  100  is checked through acceleration and angular speed. Also, the electronic apparatus  100  may determine whether the door is opened or closed, according to the sensed arrangement form. 
     For example, if the door is a door that is pivotable based on an axis of the doorframe, the electronic apparatus  100  may sense the arrangement form based on the measured acceleration. The electronic apparatus  100  may determine a movement angle by performing a definite integral with respect to the measured angular speed. In this case, the electronic apparatus  100  may compensate for an angular speed value by using the measured acceleration. Since errors caused by the definite integral gradually increase, the electronic apparatus  100  may compensate for the angular speed value by using a Kalman filter or a complementary filter. 
     As another example, if the door is a sliding door that is movable back and forth in a straight line direction based on the doorframe, the electronic apparatus  100  may sense the arrangement form based on the measured acceleration. The electronic apparatus  100  may sense a movement distance by using an acceleration value. The electronic apparatus  100  may also sense in which direction the door slides, by using an angular speed value. 
     In operation S 730 , the electronic apparatus  100  may transmit the determined state of the door to the external apparatus  200 . The electronic apparatus  100  may be connected to the external apparatus  200  to form an Internet of Things (IoT) environment. 
       FIG. 8  is a flowchart of a method of determining a door state of the electronic apparatus  100 , according to another exemplary embodiment. The exemplary embodiment of  FIG. 8  is a flowchart for describing an operation performed after a state of a door is determined as a closed state. 
     In operation S 810 , the electronic apparatus  100  may determine the state of the door as the closed state. For example, the electronic apparatus  100  may determine that the state of the door is the closed state, based on an angle range sensed by the gyro sensor. 
     If an acceleration shock occurs when the door is in the closed state, the electronic apparatus  100  may sense an acceleration change. If the acceleration change is sensed in operation S 820  (S 820 -Y), the electronic apparatus  100  may determine whether an angular speed change also occurs in operation S 830 . 
     If the angular speed change is sensed in operation S 830  after sensing the acceleration change (S 830 -Y), the electronic apparatus  100  may determine that the door pivots. In other words, the electronic apparatus  100  may determine the state of the door as an opened state in operation S 840 . 
     If the acceleration change is sensed but there is no angular speed change in operation S 830  (S 830 -N), the electronic apparatus  100  may determine that the state of the door is maintained as the closed state in operation S 850 . Also, the electronic apparatus  100  may determine a detailed state occurring in the closed state. 
     In detail, the electronic apparatus  100  may determine the detailed state of the door on which the electronic apparatus  100  is installed, according to a preset acceleration change pattern in operation S 860 . For example, the electronic apparatus  100  may determine the state of the door as one selected from a knock state, a vibration state caused by an environment such as wind and the like, and an external intrusion attempt state. The electronic apparatus  100  may respectively determine states of the door based on intensity, a cycle, and a number of acceleration changes. 
     If the state of the door is determined as a state where a notification message needs to be transmitted to a user as in the knock state or in the external intrusion attempt state, the electronic apparatus  100  may notify the external apparatus  200  of the state of the door. 
     The electronic apparatus  100  according to various exemplary embodiments as described above may be simply installed on a door so as to determine various states of a door such as opening and closing, vibrations, knocks, external intrusions, and the like. 
     Methods as described above may be embodied as a program command form that may be performed by various types of computer means and then may be recorded on a non-transitory computer readable medium. The computer readable medium may singly include or may combine a program command, a data file, a data structure, and the like. The program command recorded on the computer readable medium may particularly designed or constituted for the embodiments or may be well known to and used by software developers. Examples of the computer readable medium include magnetic media such as a hard disk, a floppy disk, and a magnetic tape, optical media such as a CD-ROM and a DVD, magneto-optical media such as an optical disk, and a hardware device that is particularly configured so as to store and perform a program command, such as an ROM, an RAM, a flash memory, and the like. Examples of the program command include a machine language code that is formed by a compiler and a high-level language code that may be executed by a computer by using an interpreter or the like. The hardware device may be configured to operate as one or more software modules so as to perform an operation of the embodiments, and an opposite case thereof is possible. 
     The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art. 
     Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit thereof, the scope of which is defined in the claims and their equivalents.