JP4333809B2 - Electronic circuit and control method thereof - Google Patents

Description

The present invention relates to an electronic circuit with a wireless communication function. In particular, the present invention relates to a small and low power consumption electronic circuit suitable for constructing a sensor network system.

In recent years, a network system (hereinafter referred to as a sensor network) in which a small electronic circuit having a wireless communication function is added to a sensor and various information in the real world is taken into an information processing device in real time has been studied. A wide range of applications is considered for sensor networks. For example, a small ring-type electronic circuit that integrates a wireless circuit, processor, sensor, and battery monitors the pulse and other data at all times, and sends the monitoring result to the diagnostic device via wireless communication. In addition, medical applications such as determining the health status based on the monitor result are also considered (Non-patent Document 1).

However, in order to put the sensor network into practical use, an electronic circuit (hereinafter referred to as a sensor node) on which a wireless communication function, a sensor, and a power source such as a battery are mounted is maintenance-free for a long time and sensor data. It is important to continue to transmit and to reduce the outer shape. For this reason, development of a sensor node that can be installed anywhere is very small. At the present stage, it is considered necessary from the standpoint of maintenance cost and usability to be usable without replacing the battery for a period of about one year.

Thus, the sensor node is required to be ultra-small and have low power consumption. For example, Non-Patent Document 2 introduces a prototype of a small sensor node having a diameter of about 3 cm called “Mica2Dot”. The Mica2Dot includes an RF chip that integrates functions necessary for wireless communication and a processor chip with low power consumption.
In this prototype, 99% of the time is in a standby state, and only the remaining 1% of time is intermittently activated and the sensor is moved to perform wireless communication of the results. Operation is possible. In this sensor node, wireless communication is performed using frequency bands such as 260 to 470 MHz and 902 to 928 MHz that are usable in the United States without requiring a license. In general, in order to perform wireless communication, it is necessary to use a special transmitter / receiver that is licensed or pre-authenticated. Therefore, if a frequency that does not require a license is used, it can be installed without labor and cost, and the construction of the system is facilitated. Therefore, it is advantageous to use such a frequency band. In particular, in the United States, the maximum value of the transmission power is stipulated to be 11 mV / m or less in the 433 MHz band and 50 mV / m or less in the 900 MHz band (all at a distance of 3 m from the transmission point). Among the frequency bands that do not require a license, good communication performance and cost reduction are realized by using frequency bands in which the regulation values of transmission power are relatively relaxed.

However, radio wave regulations differ depending on the country or region. For example, radio wave regulations in Japan are as described in Non-Patent Document 3, and the electric field strength allowed in the frequency band that does not require a license is alleviated. Not necessarily.
Non-Patent Document 4 discloses a small button battery suitable as a power source for a sensor node.

Sokwoo Rhee et al. `` Artifact-Resistant Power-Efficient Design of Finger-Ring Plethysmographic Sensors '', IEEE Transactions On Biomedical Engineering, Vol.48, No.7, July 2001, pp.795-805

Crossbow “Smarter Sensors In Silicon” [online] [Search February 16, 2004], Internet <URL: http://www.xbow.com/Support/Support_pdf_files/Motetraining/Hardware.pdf> “Weakly used wireless devices” [online] [searched on February 17, 2004], Internet <URL: http://www.circuitdesign.jp/jp/technical/technical_pdf/bijaku.pdf.PDF> “Data Sheet CR2032” [online] [searched on February 21, 2004], Internet <URL: http://www.maxell.co.jp/e/products/industrial/battery/pdf/CR2032_DataSheet.pdf>

Radio resources indispensable for wireless communication (available frequency band and maximum transmission power) vary depending on the country and region. As shown in Non-Patent Document 3, the radio resources that can be used without license in Japan are as follows. It is street.
Frequency band of 1.322 MHz or less or 10 GHz or more Frequency band of 500 μV / m or less 2.322 MHz or more and 10 GHz or less at a distance of 3 μm from the transmission point 35 μV / m or less at a distance of 3 m from the transmission point.

This regulation value is much stricter than the regulation value in the United States. For this reason, in order to use a sensor node designed on the assumption of high transmission power in a severe radio wave regulation environment, the transmission power must be made lower than the initial set value. However, it does not operate well because it can receive only power much lower than the power originally assumed at the receiving side. For example, if a sensor node designed under US radio wave regulations is to be used under Japanese radio wave regulations, the transmission power must be reduced from 50 mV / m to 35 μV / m in the 900 MHz band. It is. That is, the radio field intensity is 63 dB (= 20 × log (50 mV / 0.03
5 mV)) also needs to be weakened.

In a general RF chip, the minimum reception sensitivity (minimum value of the signal level of a receivable high-frequency radio signal) is about −100 dBm. If the radio field intensity is weakened by 63 dB, reception is almost impossible. Specifically, what can be transmitted and received stably at a distance of several tens of meters may fall into a situation where communication is impossible even at a distance of several meters. Use frequency 3
If the frequency is changed to 15 MHz, the radio wave intensity is allowed to be 500 μV / m, so the situation is somewhat improved. However, even in this case, 40 dB (= 20 × log (50 mV / 0.5 mV
)) Will also deteriorate, and it will be inevitable that the communication distance will deteriorate.

In order to improve the reception sensitivity, first, the RF chip must be made more sensitive. However, it is considered difficult to further improve the sensitivity with the current CMOS technology. for that reason,
A method of increasing the reception sensitivity by adding an external high frequency low noise amplifier (Low Noise Amplifier, LNA) to the input of the RF chip is widely performed. Add such an amplifier,
If the received signal is amplified by about 20 dB, the communication distance of about 10 m is theoretically possible.

However, this was not enough in the range we actually tried. Usually, in a sensor node, a processor chip and an RF chip are very small regions (˜several c) due to size restrictions.
m square). On the other hand, as is well known, when wireless communication is performed with a weak high-frequency wireless signal such as a sensor node, the reception sensitivity cannot be easily improved due to the radiation noise from the processor chip. Usually, digital circuits exchange signals with square waves. A square wave is composed of alternating signals of various frequency components, and includes signals in a frequency band very close to signal components used in wireless communication. On the other hand, the RF chip amplifies a very weak high-frequency radio signal (typically on the order of μV or less) and demodulates desired data. For this reason, if the signal of the digital circuit wraps around even the input part of the RF chip, the RF chip cannot properly demodulate the high-frequency radio signal from the antenna. In addition, even with frequency components that are completely different at first glance, a new frequency component signal is synthesized by the input / output nonlinear characteristics of the semiconductor device used inside the amplifier circuit LNA and RF chip, and a noise signal appears in the frequency band to be received. Resulting in. So in the worst case,
It may also mean that the amplifier LNA added for the purpose of increasing the reception sensitivity is amplifying radiation noise from the processor chip. Therefore, in the sensor node, it is necessary to solve the conflicting problems of downsizing and improvement of reception sensitivity.

Further, the use of the amplifier LNA affects the power consumption and thus the battery life. Amplifier LN
Even if A has a function of reducing the power consumption by setting the entire amplifier LNA chip in a standby state when not in use, a standby current of about 10 μA at the maximum is consumed in the standby state. In order to make the sensor node maintenance-free and to be compact and capable of operating for a long time, a button battery must be used. However, with such a button battery, the current capacity is at most 2
00 mAh. Therefore, if a current of about 10 μA is constantly consumed by the amplifier LNA, about 2 years (2.28 = 200 mAh / 0.01 mA / 24 h /
Only 365 days). Actually, it is known that the battery capacity is reduced depending on conditions, for example, the battery capacity is reduced at a low temperature, which further shortens the battery life.

The usage is important from the viewpoint of battery life. As shown in Non-Patent Document 4, in a button battery, if a large current exceeding several mA is kept flowing, the battery capacity is extremely deteriorated. Furthermore, as a result of verification by the inventor, when using a button battery, the battery capacity is extremely deteriorated if the peak current is not suppressed even when the button battery is used in a pulsed manner (intermittently). The problem was found. According to the inventor's actual measurement, the same phenomenon is observed even when a current of about 10 mA is consumed in a pulsed manner. In the sensor node so far,
For example, as shown in Non-Patent Document 2, the average current consumption is reduced by suppressing the duty ratio (ratio of the actual operation time and intermittent operation time interval in intermittent operation) to 1% or less. It aims to extend battery life. Therefore, the method of reducing the duty ratio and reducing the average current consumption may cause the battery capacity to be extremely deteriorated if a large peak current is generated, which may shorten the battery life.

In an RF chip that can be realized by the current semiconductor technology, a current of about 10 mA is required for transmission and reception, and a current of about 5 mA is required to operate a processor chip with low power consumption. Furthermore, the amplifier LNA also requires a current of 10 mA. Therefore, as a whole, a current of about 20 mA is required for transmission and reception. For this reason, as disclosed in Non-Patent Document 2, even if the device is operated at a duty ratio as low as about 0.1% and the apparent current consumption is suppressed to about 10 μA, in reality, a button battery with a peak current is used. Due to the capacity degradation phenomenon, the life may be considerably shortened. Furthermore, considering the current consumption of the sensor, the actual battery life is much shorter. In a general sensor network application, a temperature sensor, an acceleration sensor, an optical sensor, or the like can be considered as a sensor. Among these, a temperature sensor with a few μA is available. However, the optical sensor-based pulse sensor disclosed in Non-Patent Document 1 requires a current of several mA at the peak. Further, even if the current consumption of the temperature sensor is several μA, if it is always activated, the current capacity of the button battery is limited, so the influence on the operating life cannot be ignored (5 μA). Even in the case of 200mAh / 5μA
/ 24h / 365day = only 4.5 years).

Therefore, according to the present invention, the effect of noise is eliminated as much as possible, the effective reception sensitivity is increased by the amplifier LNA, and the peak current is kept low while the standby current is suppressed as much as possible, thereby reducing the deterioration of the battery capacity of the button battery. Thus, a practical sensor node that is small and has a long lifetime is provided.
Furthermore, in the present invention, it is possible to control the processor chip / RF chip / LNA / sensor comprehensively and minimize standby current and peak current in the sensor node in order to maximize the battery life. A control method is provided.

The typical ones of the present invention are as follows. The electronic device of the present invention receives a sensor data input from a sensor via a substrate, a connector for connecting the sensor, and the connector,
A first signal processing circuit for forming transmission data; and a second signal processing circuit for converting a transmission signal from the first signal processing circuit into a high-frequency signal. The connector and the first signal processing circuit are substrates. And the second signal processing circuit is mounted on the second surface of the substrate. As a result, the digital circuit and the high-frequency circuit that are noise sources are separated. In order to enhance the effect, a noise shield layer is provided on the substrate. Furthermore, the arrangement of each surface is devised so that the circuit that becomes a noise generation source and the circuit that is sensitive to noise are kept away.

Further, the electronic device is assumed to operate intermittently, and a circuit that is not used is configured to be able to shut off the power. For example, the high-frequency low-noise amplifier LNA shuts off the power when the receiving operation is not performed, and shuts off the power supply to the sensor when the sensing operation is not performed.
Furthermore, the sum of the current consumption required for the internal processing and the current consumption required for the transmission / reception processing for an electronic device configured such that power is supplied by the button battery and internal processing and transmission / reception processing with the external device can be performed simultaneously Is determined to exceed the predetermined current amount, the internal processing and the transmission / reception processing are executed at different timings, and the sum of the current consumption required for the internal processing and the current consumption required for the transmission / reception processing does not exceed the predetermined current amount. When it is determined that the internal processing and the transmission / reception processing overlap, the internal processing and the transmission / reception processing are executed. Even if the button battery is temporary, if a large peak current flows, the battery life is deteriorated. Therefore, the operation timing is determined based on the estimated current consumption.

According to the present invention, a sensor node having a practical communication distance performance and a practical operation life can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the component which attached | subjected the same code | symbol shows the same or similar structure.
FIG. 1 shows a state in which a circuit constituting the sensor node SN1 is mounted on the front surface SIDE1 of the substrate BO1, and FIG. 2 shows a state in which the circuit is mounted on the back surface SIDE2 of the substrate BO1. As shown in FIG. 1, a high-frequency signal processing chip CHIP1 (hereinafter, referred to as a high-frequency signal processing chip CHIP1)
(Referred to as “RF chip”), first crystal resonator X1, high-frequency switch RFSW, high-frequency low-noise amplifier LNA, matching circuit MA, interface IF1 with circuits mounted on backside SIDE2, display device DISP, and capacitor C1 , C2, C3, and C4 are mounted. Further, as shown in FIG. 2, the backside SIDE 2 has a processor chip CHI.
P2, connector CN1, first and second power cut-off switches (PS1, PS2), temperature sensor TS1 as an internal sensor, second and third crystal resonators (X2, X3), and surface SIDE1 Switch IFSW and amplifier LNA interface IF1
An RFSW / LNA control circuit LSC that is controlled via the control circuit is configured. An external sensor is connected to the connector CN1. A ceramic resonator can be used instead of the quartz resonators X1 to X3.

The RF chip CHIP1 and the processor chip CHIP2 are connected to each other by an interface IF1. The processor chip CHIP2 is connected to the internal sensor or from the connector C
Collect sensor data from external sensor via N1 and send sensor data to interface IF1
It passes to RF chip CHIP1 via. The RF chip CHIP1 converts the sensor data into a radio signal and transmits it to an external radio terminal installed outside the sensor node SN1. Also,
Conversely, a radio signal from an external radio terminal is received. Typically, an external wireless terminal transmits a sensor data transmission request, operation parameters such as a wireless communication frequency and transmission rate, and the data received by the sensor node SN1 is sent to the processor chip CHIP2 via the interface IF1. To be used for setting up the next wireless communication.

FIG. 3 is a cross-sectional view of the sensor node SN1. As shown in this figure, the substrate B
A ground plane GP1 and a power plane VP1 are installed inside O1. These two planes are used as shields for the front and back of the substrate BO1, and reduce noise generated from the processor chip CHIP2 and the like transmitted to the high-frequency circuit mounted on the surface SIDE1, thereby improving effective reception sensitivity. The ground plane GP1 has a ground potential (
Reference potential) Connected to a via (for example, via V20) connected to GND, ground potential GN
D is given. The power supply plane VP1 is connected to a via (for example, the via V10) connected to the power supply line VDD, and is supplied with the power supply potential VDD. 4 and 5 are diagrams showing the planar configurations of the ground plane GP1 and the power supply plane VP1, respectively. In the ground plane GP1, a plane layer is not provided so as not to be in contact with a via in a portion other than a via (for example, V20) that may be connected to the ground. This corresponds to the via holes VH10 to VH10-15 for passing the vias connected to the power supply potential VDD and the via hole VHI1 for passing the interface IF1 shown in FIG. Similarly, in the power plane VP1, no plane layer is provided around a via that is not connected to the power plane VP1 (FIG. 5).

In FIG. 3, the plane layer closer to the RF chip CHIP1 out of the two plane layers is the ground plane GP1, but this is the power impedance of the ground plane GP1 when viewed from the high-frequency circuit on the surface SIDE1. This is a preferable configuration because it can be lowered. 4 and 5, the plane layer is provided on the entire surface other than the via hole. However, a part of the plane layer can be used as the wiring layer of the back surface SIDE2 or the front surface SIDE1.

Next, the processor chip CHIP2 mounted on the back surface SIDE2 of the substrate BO1 will be described with reference to FIG. The processor chip CHIP2 includes a memory circuit MEM, a processor circuit CPU, a data input / output circuit SIO, an A / D conversion circuit ADC, a timing generation circuit TIM, and a programmable input / output circuit PIO. These circuit blocks are coupled to each other by an internal bus BU1 to exchange and control data.

The memory circuit MEM includes a low power consumption SRAM (Static Random Access Memory) and a nonvolatile memory such as a flash memory. On the memory circuit MEM, software for realizing a control method unique to the present invention, which will be described later, is mounted. The processor circuit CPU controls other circuit blocks in the processor chip CHIP2 in accordance with the installed software to realize a desired operation.
The data input / output circuit SIO is an input / output circuit for serial data, and is used to send sensor data to the RF chip CHIP1. The programmable input / output circuit PIO is an input / output circuit for parallel data, and is mainly used for input / output of control data necessary for controlling an operation mode such as transmission / reception of the RF chip CHIP1.

An external sensor is connected to the connector CN1, and the external sensor may output analog data or digital data. The sensor data AP of the analog type sensor is converted into digital data by the AD conversion circuit ADC. For example, an analog type temperature sensor TS1 is built in the substrate BO1 in the sensor node SN1, and the temperature data AT from the sensor TS1 is converted into a digital quantity by the AD conversion circuit ADC and is stored in the memory MEM as necessary. Stored in On the other hand, the digital type sensor data DP is input to the processor chip CHIP2 via the programmable input / output circuit PIO, and stored in the memory MEM as necessary.

Further, the processor chip CHIP2 controls the RFSW / LNA control circuit LSC to turn on / off the power supply of the amplifier LNA and switch transmission / reception of the high frequency switch RFSW. Further, the processor chip CHIP2 controls the power cutoff switches PS1 and PS2 to control the on / off of the power supply of the temperature sensor TS1 and the external sensor. The timing generation circuit T
IM generates a timing required for operation, for example, a clock signal or a timer signal used in an intermittent operation described later, from the oscillation frequency of the crystal resonator X2 or X3.

Note that the processor chip CHIP2 uses two crystal resonators for low power consumption operation. The crystal resonator X2 is for a main clock, for example, having a frequency of several MHz or more. The current consumption when using the main clock is typically several mA. Meanwhile, crystal unit X3
Is used to generate subclock and timer signals, for example, 32 KHz used for watches
It is composed of ultra-low power consumption type. The processor chip CHIP2 can reduce the current consumption to 10 μA or less by stopping the main clock X2 in the low power consumption mode and driving the processor chip with the sub clock X3. Further, among the above circuit blocks, the AD conversion circuit ADC, the data input / output circuit SIO, the programmable input / output circuit PIO, and the memory MEM suppress the current consumption during standby by stopping the clock supply under the control of the processor circuit CPU. A standby current of several μA or less can be realized.

Next, referring to FIG. 1, the RF chip CH mounted on the surface SIDE1 of the substrate BO1.
IP1 will be described. The RF chip CHIP1 includes a high frequency modulation / demodulation circuit RF and an oscillation circuit O.
It is composed of an SC and a control circuit CON. The sensor data DS sent from the processor chip CHIP2 is converted into a high-frequency radio signal RFO in a predetermined frequency band (up to 315 MHz) by the high-frequency modulation / demodulation circuit RF and transmitted to an external radio terminal. A high frequency radio signal from the external radio terminal is received by the antenna ANT1, and demodulated by the high frequency modulation / demodulation circuit RF. The demodulated signal CS is sent to the processor chip CHIP2 via the interface IF1.
To be handed over. The sensor node SN1 monitors the reception intensity, and the signal AS indicating the reception intensity is also delivered from the RSSI terminal of the high frequency modulation / demodulation circuit RF to the processor chip CHIP2 via the interface IF1.

The oscillation circuit OSC is based on the oscillation frequency of the crystal resonator X1, and the RF chip CHIP.
1 A clock signal necessary for the entire operation and a high frequency signal (carrier frequency signal) of the target wireless communication band are generated.
Further, the high frequency modulation / demodulation circuit RF and the oscillation circuit OSC are controlled by the control circuit CON in accordance with the control signal CS of the processor chip CHIP2. Specifically, switching of operation modes such as transmission and reception, fine adjustment of frequency bands of transmission / reception signals, transmission power, and the like are controlled. Further, it is possible to stop the oscillation circuit OSC by a control signal from the processor chip CHIP2 and shift the entire RF chip CHIP1 to a standby state. In this case, the current consumption of the RF chip CHIP1 can be reduced to typically 1 μA or less.
The operation and configuration of other components will be described as follows.

The high frequency switch RFSW is controlled by an RFSW / LNA control circuit LSC provided on the back surface SIDE2. A desired transmission / reception operation is realized by switching the connection between the antenna ANT1 and the RF chip CHIP1. Specifically, at the time of transmission, the RI terminal and the RO2 terminal of the high frequency switch RFSW are made conductive. At the time of reception, the RI terminal and the RO1 terminal are made conductive.

The amplifier LNA is externally attached to the RF chip CHIP1, and amplifies a very weak high-frequency radio signal received by the antenna ANT1 to a level that can be demodulated by the RF chip CHIP1. Here, the reason why the amplifier LNA is externally attached is to use an element formed by a process different from that of the RF chip CHIP1. The RF chip CHIP1 is preferably composed of a CMOS circuit for cost reduction and low power consumption operation. On the other hand, however, the CMOS circuit has a problem that the gate noise is large, and it is not good at amplifying a weak high-frequency radio signal. Therefore, as the amplifier LNA, a circuit formed by a process not compatible with CMOS is used, and an external circuit is used. The amplifier LNA is preferably composed of a compound semiconductor such as GaAs, SiGe, or a bipolar circuit in consideration of its amplification capability. The high frequency radio signal received by the antenna ANT1 is input to the input terminal L of the amplifier LNA.
I is input to I, amplified by a predetermined amplification factor, and then output via the output terminal LO. Amplifier L
The NA amplification factor is preferably about 10 to 20 dB when it is desired to stably communicate at a communication distance of about 10 m in the 315 MHz band. Further, since the amplifier generally consumes a large amount of current, the operation state and the standby state are switched by controlling the enable terminal LE, and the current consumption during standby can be reduced to about 10 μA typically. However, if a current of 10 μA is constantly consumed in the sensor node SN1, the battery life is seriously affected.
In this embodiment, the power supply to the amplifier LNA is cut off by the control from the processor chip CHIP2, thereby reducing the power consumption of the sensor node SN1.

The matching circuit MA is a circuit for matching the input / output impedance of the RF chip CHIP1 with the input / output impedances of the high-frequency switch RFSW and the amplifier LNA so that a high-frequency radio signal can be transmitted between these elements without loss. . The matching circuit MA is composed of passive components such as an inductor, a capacitor, a resistor, or a filter.
FIG. 6 is a diagram illustrating a state where the circuit mounted on the front surface SIDE1 and the circuit mounted on the back surface SIDE2 are connected via the interface IF1. The interface IF1 includes a data signal line DS, a control signal line CS, a display device (DISP) control line DC, an LNA enable terminal control line LC, an RFSW transmission / reception switching control line RC, and a power supply line VDD / LN.
A power supply line VDD1 is comprised.

The data signal line DS is connected to the data input / output circuit circuits SIO and R of the processor chip CHIP2.
This is a signal line for connecting the high frequency modulation / demodulation circuits RF of the F chip CHIP1. The control line signal CS is a signal line that connects the programmable input / output circuit PIO of the processor chip CHIP2 and the control circuit CON of the RF chip CHIP1. The data signal line DS is used for data exchange between the two chips, and the control signal line CS is used as a control line for the processor chip CHIP2 to switch the operation mode of the RF chip CHIP1. Further, the display device control line DC is used to control the display device DISP. FIG. 7 shows the display device DISP.
The example of a structure is shown. The display device DISP includes a light emitting diode LD10 and a light emitting diode LD1.
Inverter IV10 for driving 0 and resistor R10 for current limiting of light emitting diode LD10
Consists of The display device DISP is turned on, for example, when the wireless communication with the external wireless terminal is successful at the time of installation, or when an abnormal state such as a failure occurs, and is turned on or off by the display device control line DC.

The LNA enable terminal control line LC, the RFSW transmission / reception switching control line RC, and the LNA power supply line VDD1 are controlled by the RFSW / LNA control circuit LSC. FIG. 8 shows a configuration example of the control circuit LSC. The two input terminals LI1 and LI2 of the control circuit LSC are controlled by signals output from the programmable input / output circuit PIO of the processor chip CHIP2. When starting up the amplifier LNA, LI1 is set to “0” to bring the power cutoff switch PS20 into a conductive state, and the power line VD of the amplifier LNA.
Energize D1. At this time, when LI2 is set to “1”, the LNA enable control line LE is set to “0”, thereby activating the amplifier LNA. At the same time, the RFSW control line RS-1 having the same level as the control line LE is set to “0”, and the RFSW control line RS-2 is set.
Is set to “1” by the inverter IV21, the high frequency switch RFSW conducts the reception path and cuts off the transmission path. On the other hand, when LI2 is set to “0”, the amplifier LNA is deactivated, and the high frequency switch RFSW conducts the transmission path and cuts off the reception path.

The features of this embodiment are summarized below.
(1) A board BO is connected to a high-frequency circuit that handles weak high-frequency radio signals and other digital parts.
1 is separated into a front surface and a back surface to reduce the influence of noise and improve reception sensitivity. As described in the background art, when the sensor node is used, severe restrictions may be imposed on the maximum transmission power. In such a case, the RF chip alone has insufficient reception sensitivity, and it is necessary to supplement the reception sensitivity with an external high frequency low noise amplifier LNA. However, even if such an amplifier is provided, a received signal to be amplified cannot be amplified unless noise wraparound from the digital portion is minimized. In such a case, it is most effective to separate the RF unit and the digital unit from each other in order to suppress noise wraparound. However, in the sensor node, it is desirable to reduce the size, particularly the surface area as much as possible, and it is not desirable that the surface area be increased in order to increase the distance between the high-frequency circuit and the digital circuit.

Therefore, the high-frequency circuit and the digital circuit are separated from each other on the front and back of the board, and a ground plane and a power plane effective for shielding noise signals are installed inside the board. First, noise from the digital circuit is shielded by this ground plane, and the wraparound to the RF section can be suppressed as much as possible. Furthermore, it is possible to provide a capacitance between the power plane and the ground plane by arranging the power plane immediately below the ground plane. This electrostatic capacity can be used as a bypass capacitor that is effective in absorbing noise that may circulate from the digital circuit to the power supply circuit. With this electrostatic capacity, it is possible to minimize noise that may circulate from the digital circuit to the high-frequency circuit via the power supply circuit. In particular, by spreading the power plane and ground plane as much as possible on the board BO1,
It is possible to keep the impedance of the power supply unit small. As a result, even if some noise from the digital circuit circulates into the high frequency circuit, the power supply impedance is kept low, so that the voltage amplitude of the noise component can be kept small. This is because the noise voltage is represented by the product of the sneak noise current and the power source impedance. As a result, even if some noise circulates from the digital circuit to the high-frequency circuit, the high-frequency circuit can malfunction, or the level can be suppressed to a level that masks the weak RF signal from the antenna. It becomes.

In this embodiment, when components are mounted at high density on both the front and back surfaces of the board, the mounting surface is not only separated but also arranged at each mounting surface so as to further improve reception sensitivity. Devised a device. As shown in FIGS. 1 and 2, in this embodiment, R
The part that handles high-frequency radio signals with a weak level in the high-frequency circuit, such as the input of the F chip, the amplifier LNA, the high-frequency switch RFSW, and the antenna ANT1, and the digital signal is frequently “0” / “1” in the digital circuit. And place it as far away as possible from a circuit that generates a large amount of noise. FIG. 9 is a diagram illustrating this structure in an easy-to-understand manner.

As shown in FIG. 9, the weak high frequency radio signal RFS received by the antenna ANT1.
1 is input to the high frequency switch RFSW. The high-frequency radio signal RFS2 selected by the high-frequency switch RFSW and somewhat attenuated is input to the amplifier LNA and amplified at a predetermined amplification factor. The amplified high-frequency radio signal RFS3 is guided to the matching circuit MA, and the impedance-matched high-frequency radio signal RFS4 is input to the RF chip CHIP1. R
In the F chip CHIP1, the high-frequency radio signal RFS4 is demodulated into a digital signal DJS1 and taken into the processor chip CHIP2 via the interface IF1.

In a wireless communication device such as a wireless LAN, a connector for communicating with a digital signal is generally used for the purpose of exchanging a digital signal with a personal computer body. Therefore, the connector is frequently “0” / “1”. "Transition between, that is, high-speed digital signals are exchanged. For this reason, there is an example in which the connector is separated from the antenna by a distance. On the other hand, in the sensor node SN1 of this embodiment, an external sensor is connected to the connector CN1, and the signal DJ exchanged between the connector CN1 and the processor chip CHIP2.
P1 is an analog signal having a very slow transition, or a digital signal that is slower than the clock signal of the processor chip CHIP2. Therefore, in this embodiment, the connector CN1 is arranged at a position close to the signal path of the antennas ANT1 to RF chip CHIP1, and the processor chip CHIP2 is arranged at a position far from the signal path of the antennas ANT1 to RF chip CHIP1. . In other words, the connector CN1 and the RF chip CHIP1
The connector CN1 is arranged such that the distance between the connector chip CHIP2 and the RF chip CHIP1 is longer than the distance between the processor chip CHIP2 and the RF chip CHIP1. As described above, the component arrangement shown in FIG. 9 is a component arrangement that can grasp both the signal flow specific to the sensor node and realize both the size reduction and the improvement of the reception sensitivity at the same time.

(2) Power cut-off switch on the power line of the high-frequency low-noise amplifier LNA (see FIGS. 1, 2 and 8)
Insert and suppress current consumption during standby. The high-frequency low-noise amplifier LNA generally consumes a large amount of power, and consumes a current of about 10 μA even during standby. This current value is too large for a sensor node that cannot obtain a sufficient power supply due to size and application restrictions. However, there are cases where a practical communication distance cannot be achieved without the amplifier LNA.

Therefore, as shown in FIG. 8, a power cutoff switch PS20 is inserted into the power line of the amplifier LNA, and the current consumption during standby is reduced by this PS20. As shown in FIGS. 10A to 10E, this power cut-off switch is composed of (a) a P-MOSFET MP1, (
b) composed of PNP bipolar transistor BP1, (c) N-MOSFET M
Nd, (d) NPN bipolar transistor BN1, (e
) Various types can be used, such as using the output of the programmable input / output circuit PIO as it is. Both types are programmable input / output circuits P of the processor chip CHIP2.
If the control terminals SC1 to SC5 driven from the IO output terminal are set to "1" or "0", the power supply to the LNA can be cut off. Actually, although some leakage current flows even when the switching elements MP1 to BN1 are turned off, the catalog value is on the order of 0.1 μA or less,
It can be considered that such an off-state leakage current hardly affects the battery life.

On the other hand, during operation, a slight voltage drop occurs due to the internal resistance of these switching elements MP1 to BN1. However, for example, in the type of FIG.
The internal resistance when 1 is turned on can be about 5Ω. As already mentioned, the amplifier LN
The current consumption during the operation of A is about 10 mA, and the voltage drop due to the switching element MP1 is about 50 mV (= 5Ω × 10 mA), which is a negligible value. Note that FIG.
As shown in 0 (e), the programmable input / output circuit PIO of the processor chip CHIP2
When there is a sufficient margin in the output drive capacity of the device, that is, when a current value greater than the current value necessary for operation can be sufficiently supplied, there is no switching element as shown in FIGS. It would be possible to drive the power supply of the amplifier LNA.

As described above, in this embodiment, when the amplifier LNA is not used (except during reception), the power cutoff switch PS20 is shifted to the cutoff state, and when the amplifier LNA is used (during reception), the power cutoff switch PS20 is in the conduction state. Transition to. Actually, even when the power cut-off switch is changed from the cut-off state to the conductive state, it is necessary to wait for the internal circuit of the amplifier LNA to be stabilized, which typically takes about 1 ms. However, in general, the sensor node SN1 has a very long standby time compared to the operation time. In some cases, the operation time is assumed to be about 1% of the entire operation time.
The increase in power consumption due to the waiting time for switching to the reception state may be ignored.
(3) Insert a power cut-off switch (see Fig. 2) into the power line of the sensor (built-in and external) to reduce the current consumption during standby. It can be said that the same principle as the second feature of this embodiment is applied to reduction of current consumption during standby of the sensor. For example, as shown in FIG. 2, the power supply line VDD2 of the built-in temperature sensor TS1 can be cut off by the power cut-off switch PS1 when the temperature sensor TS1 is not used. At present, a temperature sensor of a low power consumption type (current consumption is about 5 μA) has been developed, and the power cut-off switch PS1 has sufficient current necessary for operation even with the type as shown in FIG. 10 (e). It can be supplied. The type shown in FIG. 10E does not require an additional discrete element and can be realized without additional cost.

In order to reduce the power consumption of the external sensor, the connector CN for connecting the external sensor
One power line VDD3 is also shut off by the power shutoff switch PS2 (see FIG. 2). In general, the power consumption of an external sensor is larger during both standby and operation than the built-in temperature sensor. For example, some acceleration sensors require a current consumption of 1 mA, and the external sensor itself often does not have a function of shifting to a standby state. Therefore, if the power cut-off switch is not used as in the present embodiment, about one week (8.3 days = 200 mAh) for the button battery.
/ 1 mA / 24 h) is expected to be obtained. Furthermore, if the battery capacity deteriorates when discharged with a large current, it is expected that the battery has only a few days. On the other hand, it is possible to drastically improve the battery life by supplying power only when using the power cutoff switch and shutting off the power when not in use.

This configuration is also effective when the external sensor has failed in the short mode for some reason. That is, if the external sensor fails in the short mode, if the power supply of the external sensor is not shut off, a large current flows from the battery instantaneously and the battery is used up. However, in this embodiment, the external sensor power supply is normally in an off state,
The power is turned on only when the sensor is used. Furthermore, since the power is supplied through the switching element that constitutes the power cutoff switch, the on-resistance of the switching element reduces the current at the time of the short circuit, and a large current flows due to the short circuit. A voltage drop due to the resistance occurs, and it becomes impossible to secure a bias voltage necessary for the switching element to maintain the on state, and the power shut-off switch automatically returns to the off state.

During this time, the processor chip CHIP2 reads the output value of the external sensor via the built-in AD converter circuit ADC. However, since it is in a short circuit state, it can read only the abnormal value that remains stuck near the “0” potential. Absent. Therefore, if the control software installed in the processor chip has a function to judge that there is an abnormality in this case and transmit an abnormal signal wirelessly, the external sensor of the sensor node has malfunctioned. Can be detected from the outside. Furthermore, in a system that detects an abnormal signal, issue a control command to the sensor node to interrupt the use of the external sensor, and operate the sensor node so as not to use the external sensor that caused the problem. It is also possible to continue. Further, as will be described later, if the sensor node in which the external sensor has failed can be determined from the ID number stored in the memory circuit MEM1 of the processor chip CHIP2, it is possible to cope with replacement or the like.

Next, a power control method for avoiding the deterioration phenomenon of the battery capacity of the button battery due to current consumption during operation will be described in detail (see FIG. 11). When the sensor node sets and starts the node (P100) and then executes the initial setting routine (P110), the sensor node immediately shifts to the standby routine (P120). In the initial setting routine P110, the operation mode of the sensor node is set to a desired state based on the PDATA file storing the operation parameters stored in advance in the nonvolatile memory portion in the memory circuit MEM of the processor chip CHIP2. The PDATA file includes, for example, a timer interval indicating how long a transition is made from a standby state to an operating state, a wireless communication transmission rate, a frequency band to be used, an ID number assigned a unique number for each sensor node, etc. Is stored. Further, an amplifier LNA and an RF chip CHIP used in an operation mode determination routine (P200) described later.
1. Current consumption values of the processor chip CHIP2, external sensor, etc. are also stored in the PDATA file. In the initial setting routine P110, the processor chip CHIP2 operates in the low power consumption mode, and the main clock X2 of the processor chip CHIP2 and the clock X1 of the RF chip CHIP1 are also turned off. The power supply to the sensor and the amplifier LNA is also cut off.

In the standby routine P120, the timing generation circuit TI in the processor chip CHIP2
Only M is in the operating state, and the operating part is minimized. By setting like this,
The operating current during standby can be reduced to several μA, typically 5 μA or less. If a timer interrupt occurs at the timer interval set in the initial setting routine P110, the process proceeds to the next CPU activation routine (P130). Also, if the interrupt line of the processor chip is connected to the connector CN1 (FIG. 2), on-demand by an external interrupt,
It is also possible to activate a sensor node.
By the CPU startup routine P130, the main clock X of the processor chip CHIP2
2 is turned on to activate the processor circuit CPU in the CHIP2. After startup, the process proceeds to an operation mode determination routine (P200).

In the operation mode determination routine P200, a parameter / command analysis subroutine (P2
20), the current consumption for each device is read from the PDATA file already described. At this time, it is also possible to read a command received from an external wireless terminal, such as a sensor data transmission request. The command is, for example, “activate the temperature sensor and send the result”. Next, based on the read parameters and commands, the current consumption necessary for execution is estimated in the current consumption estimation subroutine (P230). In the scheduler subroutine (P210), the following sensing routine (P300) and data transmission / reception routine (P400) are performed so that the peak value of current consumption becomes the smallest after satisfying the request requested from the base station. Determine the startup method.

For example, in the sensing routine P300, when starting an external sensor whose current consumption during operation is about several mA and cannot be ignored compared with the current consumption (10 mA to 20 mA) necessary for data transmission / reception, the data transmission / reception routine P400 is not activated simultaneously. FIG. 12 shows a typical current consumption waveform of the sensor node in this case. On the other hand, when the sensor to be activated is a built-in temperature sensor or the like that consumes only about several μA of current, the data transmission / reception routine P400 is simultaneously activated. FIG. 13 shows a typical current consumption waveform of the sensor node corresponding to this case. Such power control makes it possible to reduce the peak value of current consumption.

The operation of the sensing routine P300 is as follows. First, the type of sensor to be activated is determined in the external / internal sensor determination subroutine (P310). Next, according to the sensor power supply startup subroutine (P320), PS1 is set to ON for an internal sensor, and PS2 is set to ON for an external sensor. Next, in a port open subroutine (P330), a port necessary for reading out the sensor result of the internal or external sensor is opened. For example, when reading the built-in temperature sensor TS1 shown in FIG.
The AD conversion circuit ADC of IP2 is activated, and the input terminal I2 of the ADC is set to a readable state. When the sensor to be activated is an external sensor connected to the connector CN1 shown in FIG. 2, the input terminal of the corresponding AD conversion circuit ADC or the input / output terminal of the programmable input / output circuit PIO enters the desired operation mode. Is set. In this way, the data from the sensor can be read. Then, in the next sensor data read / write subroutine (P340), the sensor data is actually transferred to the processor chip CHIP2.
And stored in the file SDATA on the memory circuit MEM. Once the desired sensor data is written in the file SDATA by the above procedure, the next port close / ADC
In the off subroutine (P350), the used AD converter circuit ADC and programmable input / output circuit PIO are shifted to a standby state, and the sensing routine P300 is terminated.

Next, the operation of the data transmission / reception routine P400 will be described. First, in the clock X1 on subroutine (P410), the clock X1 of the RF chip CHIP1 is raised and R
The F chip CHIP1 is activated. At this time, the activation of the RF chip CHIP1 by the processor chip CHIP2 is performed in the form prescribed by the RF chip via the control signal line CS already described.
Next, a transmission / reception operation determination subroutine (P420) determines whether transmission or reception is necessary. In this routine, for example, sensor data is first transmitted from the sensor node to the base station, and then the sensor node shifts to a reception state. The sensor node stands by in a reception state until a confirmation signal that the base station has received the transmitted sensor data without error is sent back from the base station. The above sequence control is executed in subroutine P420. Hereinafter, transmission and reception operations will be described.

In the case of the transmission operation, the high frequency switch RFSW is switched to the transmission state by a subroutine P430. In addition, communication parameters such as a transmission rate and a frequency band used via the control signal line CS are sent to the RF chip CHIP1. Next, according to subroutine P440, memory M
Read the sensor data from the file SDATA on the EM, and R via the data signal line DS
The sensor data is transmitted to the F chip CHIP1 by wireless communication to the outside.
In the case of the reception operation, the communication parameters of the high frequency switch RFSW and the RF chip CHIP1 are set by the subroutine P450, and the LNA power cutoff switch PS2 is set.
0 is set to the conductive state, and the enable terminal of the LNA is activated. Next, data is received in subroutine P460 and written in PDATA as necessary.

Although omitted in the above description for the sake of simplification, in actuality, it takes time to stabilize the activation of the amplifier LNA, the switching of the high-frequency switch RFSW, and the activation of the clock X1 of the RF chip CHIP1. Since (typically, several hundred μs to several ms) is required, processing for waiting for that time is required in each routine. Similarly, amplifier LN
It takes time to stabilize the power-off of A and the clock-off of the RF chip CHIP1, and waiting time processing is necessary.

When the reception confirmation signal is finally received from the base station, the clock X1 is stopped and the RF chip CHIP1 is returned to the OFF state in subroutine P470. Furthermore, subroutine P1
At 40, the main clock X2 of the processor chip CHIP2 is stopped, and the process proceeds to the standby routine P120.

As described above, in this embodiment, a necessary current consumption is determined in advance, and a method that does not deteriorate the current capacity of the button battery is selected. That is, when the sensor consumes a current of several mA, if the data transmission / reception and the sensor are activated simultaneously, the button battery is subjected to a heavy load that may seriously deteriorate the battery capacity. FIG. 14 shows a waveform example of current consumption in this case. The peak current (Ip3) becomes a considerably larger value (Ip3> Ip1) than when the control method of the present invention shown in FIG. 12 is applied. On the other hand, FIG. 12 and FIG.
As is clear from comparison, in the control method of FIG. 12, since data is transmitted / received after the sensor is activated, the time required to complete a series of processing becomes long (Ttota
l1> Ttotal3). Also, the average current consumption is somewhat larger in the case of FIG. However, when a button battery such as CR2032 is used as the power source of the sensor node SN1, the current consumption that can be used within a range in which the battery capacity is not deteriorated is at most on the order of 0.1 mA. On the other hand, a current on the order of 10 mA is required for the operation of the sensor node. However, when a button battery is used at such a current value, there is a problem that the battery life is extremely deteriorated. In order to avoid this problem, it is most effective to suppress the peak value of current consumption within the range we have verified. That is, in order to realize a long-life operation with a button battery operation sensor node, it is indispensable to suppress the peak value of current consumption to the lowest possible value. For this reason, even if the average current consumption is somewhat increased, the control method of the present embodiment in consideration of the characteristics of the button battery can be stably operated with the button battery for a long period of time.

On the other hand, when the consumption current of the sensor is about several μA, the peak value of the consumption current hardly changes even if the sensor is operated simultaneously with the transmission / reception of data. That is, if the sensor is activated and the sensor data is transmitted while reading the data from the sensor, the time required for a series of operations can be saved. That is, since it can shift to a standby state in a short time, it is possible to suppress battery consumption.
The power control method as described above enables operation taking into account the characteristics of the button battery,
As a result, a long life operation is realized during button battery operation.

FIG. 15 shows an example in which the sensor node is composed of three substrates. The sensor node includes a main body board BO1, a power supply board BO2, and a control software writing board BO3. During normal use, the main board BO1 and the power supply board BO2 are used in combination. Further, when the control software is rewritten, it is used in a combination of the main body board BO1 and the control software writing board BO3. Among these, the configuration of the main body board BO1 is the same as that of the sensor node SN1 already described, and thus detailed description thereof is omitted.

The power supply board BO2 includes a connector CN2 connected to the main board BO1, a dedicated sensor port SP1 for connecting an external sensor, and a power cutoff switch PS2 for shutting off the power of the sensor port SP1.
1, a power-on reset circuit POR1, a manual reset switch SW2, an external power connector PP1, a power selection switch SW1, a button battery BAT1, and a regulator REG1. The board BO2 supplies power from the button battery built in via the connector CN2 to the main board BO1. The sensor port SP1 is wired with a signal line for reading the sensor from the main board BO1 via CN2, and an external sensor can be connected.

Similarly, the control software writing board BO3 is connected to the main body board BO1 with a connector CN3,
Dedicated sensor port SP2 for connecting an external sensor, power shut-off switch PS21 for power shut-off of sensor port SP2, power-on reset circuit POR2, manual reset switch S
W3, an external power connector PP1, a regulator REG2, and a program rewrite port DBP mounted on the processor chip. The board BO3 obtains power from an external power source connected to the external power connector PP1, and supplies power necessary for the operation of the main board BO1. Furthermore, the control software mounted on the processor chip of the main board BO1 is rewritten via the program rewrite terminal DBP. The signal line of the program rewrite terminal is connected to the program rewrite terminal of the processor chip via the connectors CN3 and CN1, and rewrites the control software installed via this terminal.

As described above, it is possible to divide and configure the sensor nodes on the separate substrates and have the following merits. That is, it is not necessary to mount a program rewrite terminal unnecessary for normal use on the main body board BO1. For this reason, the size of the main body substrate can be reduced. On the other hand, at the time of software operation confirmation / debugging, a sensor node that is too small is difficult to handle. However, with the configuration as shown in FIG. 15, signal lines and the like necessary for debugging can be drawn out on a control software rewriting substrate whose size does not matter. That is, it is possible to reduce the time and effort required for debugging work, and the time required for development can be greatly shortened.

FIG. 16 shows an example in which a sensor network system is constructed using the sensor node of the present invention. In FIG. 16, SN1 to SN6 are sensor nodes of the present invention, and are distributed over the entire building, for example, for the purpose of controlling the air conditioning of the entire building. These separated sensor nodes perform wireless communication with the base station BS1 by wireless communication and transmit sensed temperature data. The base station BS1 includes an antenna ANT1, a radio communication interface RF1, a processor C
It comprises PU1, memory MEM1, secondary storage device STR1, display device DISP1, user interface device UI1, and network interface NI1. Of these, the secondary storage device STR1 is typically composed of a hard disk or the like. The display device DISP1 is a CRT or the like, and the user interface device UI1 is a keyboard / mouse or the like. FIG. 17 shows a data structure of sensor data transmitted from the sensor node to the base station in this system. The base station BS1 performs wireless communication with the sensor node via the wireless interface / antenna and reads measurement data such as temperature. The base station BS1 controls the temperature of the entire building according to the quality determination program QPR1 stored in the secondary storage device STR1 or the memory MEM1 based on the received measurement data. Furthermore, the wide area network W represented by the Internet etc. via the network interface NI1.
It is possible to communicate with the management server SV10 at a remote location via the AN1.

By using the sensor node of the present invention, first, since the reception sensitivity is good, even if the base station is located far away, communication with the base station can be reliably performed. That is, since the number of base stations can be reduced, the cost for introducing the sensor network system can be greatly reduced. further,
Since the sensor node of the present invention has a long battery life, it can continue to operate without problems without frequent battery replacement. That is, it is possible to greatly reduce the maintenance cost of the entire sensor network system and to construct a sensor network system having a target function at a low cost.

According to the present invention, a sensor node capable of operating with high sensitivity and low power consumption is provided, which makes it possible to construct a sensor network system in various fields.

It is a figure which shows one Embodiment (surface) of a sensor node. It is a figure which shows one Embodiment (back surface) of a sensor node. It is a figure which shows one Embodiment (cross section) of a sensor node. It is the figure which showed the ground plane layer provided in the board | substrate. It is the figure which showed the power plane layer provided in the board | substrate. It is the figure which showed the detail of interface IF1. It is the figure which showed the structural example of the LED display monitor. It is the figure which showed the structural example of the control circuit of a high frequency switch and amplifier LNA. It is the figure which showed the flow of the signal in sensor node SN1. Each of FIGS. 10A to 10E is a diagram illustrating a configuration example of a power cut-off switch applicable to the sensor node SN1. It is a flowchart of the power control method for operating a sensor node with low power consumption. It is the figure which showed the example of the consumption current waveform of a sensor node at the time of applying the power control method of FIG. It is the figure which showed the example of the consumption current waveform of a sensor node at the time of applying the power control method of FIG. It is a comparative example of the consumption current waveform of a sensor node when not applying the power control method of FIG. It is the figure which showed the structural example of the power supply board | substrate used in combination with the sensor node of this invention, and a program writing board | substrate. It is the figure which showed the structural example of the sensor network system implement | achieved by the sensor node of this invention. It is the figure which showed the structural example of the data transmitted from the sensor node of this invention in the sensor network system of FIG.

Explanation of symbols

SN1 ... sensor node, SIDE1 ... first surface of substrate, SIDE2 ... second surface of substrate, CA, CB, CC, CD ... four corners of substrate, CHIP1, CHIP2 ... semiconductor integrated circuit, C1, C2, C3 , C4: Capacitor, X1, X2, X3 ... Crystal or ceramic resonator, ANT1 ... Antenna, LNA ... High frequency low noise amplifier, RFSW ... High frequency switch, MA ... High frequency impedance matching circuit, RF ... High frequency circuit (data modulation / demodulation, (Including PLL and VCO), OSC ... oscillation circuit, CON ... control circuit, DISP ... LED display monitor, CPU ... processor circuit, ADC ... A / D conversion circuit, MEM, CMEM1 ... memory, SIO ... serial communication circuit, TM1 ... Timer circuit, PIO ... Programmable Input / output circuit, LSC ... RFSW / LNA control circuit, PS1, PS2, PS11, PS21, PS22 ... Power cut-off switch, TS ... Temperature sensor, CN1, CN2, CN3 ... Connector, VDD ... First power supply line, VDD2 ... Second power supply line, VDD3 ... Third power supply line, GND ... Ground potential, IF1 ... Interface, V1, V2, V3, V4, V5, V6, V7, V10, V11, V13, V15, V21, V22, V23 … Via (through hole) for connecting the front and back of the substrate, DS…
Data signal line, CS ... control signal line, DC ... LED display monitor control signal line, RES ... CHIP2 reset signal line, AP ... A / D conversion signal line, DP ... digital I / O signal line, AT ... temperature sensor Output signal lines, VP1... First power layer provided inside the substrate, GP1... Ground layer provided inside the substrate, VH10, VH11, VH13, VHI1, VH15. VH20, VH21, VH22, VH23, VHI1... Region provided in VP1 for passing vias, MP1... P-type MOS transistor, BP1... PNP bipolar transistor, MN1. Type bipolar transistor, IV10, IV20
, IV21 ... Inverter, R1, R2, R3, R4, R10 ... Resistor, SDATA ... File that stores the result of reading data from sensor, PDATA ... Communication condition, timer start interval, ID number unique to each sensor node , A file storing information on the current consumption value for each device, I0, I1, I2, I3, I4, I5, Ip0, Ip1, Ip2, Ip3 ... current consumption value, SP1 ... external sensor connector, SEN1, SEN2 ... external sensor , PP1 ... external power connector, REG1 ... low voltage regulator, POR ... power-on reset circuit, BAT ... battery, SW1, SW2, SW3 ... switch, DBP
... Program write terminal, VEX1 ... External power supply line, BS ... Program write signal line, HDD1 ... Secondary storage device, DISP1 ... Display device, NI1, NI10 ... Network interface, DB10 ... Database, BA1 ... Button battery.

Claims (9)

An electronic device using a button battery as a power source,
A sensor that performs sensing;
A transmission / reception circuit for performing data transmission / reception with an external device;
A memory for storing data for setting an operation mode of the electronic device;
A control device for controlling the sensing and the data transmission / reception,
The control device is an electronic device that estimates current consumption required for the sensing based on data for setting the operation mode, and determines timing of the sensing and the data transmission / reception based on the current consumption. An electronic device using a battery with a battery capacity of 200 mAh or less as a power source,
A sensor that performs sensing;
A transmission / reception circuit for performing data transmission / reception with an external device;
A memory for storing data for setting an operation mode of the electronic device;
A control device for controlling the sensing and the data transmission / reception,
The control device is an electronic device that estimates current consumption required for the sensing based on data for setting the operation mode, and determines timing of the sensing and the data transmission / reception based on the current consumption. The electronic device according to claim 1 or 2,
The said control apparatus is an electronic device which determines whether the said sensing and the said data transmission / reception are performed at a different timing based on the said consumption current, or the said sensing and the said data transmission / reception are performed at the same timing. The electronic device according to claim 1 or 2,
The control device is an electronic device that determines whether to transmit the sensing data after the operation of the sensor is completed based on the current consumption, or to transmit the sensing data while activating the sensor. The electronic device according to claim 1 or 2,
When the sensor is an external sensor connected to a connector, the control device executes the sensing and the data transmission / reception at different timings. On the other hand, when the sensor is a built-in sensor, An electronic device that performs the data transmission and reception at the same timing. The electronic device according to claim 1 or 2,
When the current consumption of the sensor in the operation mode is several mA, the control device executes the sensing and the data transmission / reception at different timings, while the current consumption of the sensor in the operation mode is several μA. Is an electronic device that executes the sensing and the data transmission / reception at the same timing. The electronic device according to claim 1 or 2,
The data for setting the operation mode includes a command transmitted from the external device,
The control device is an electronic device that determines a sensor to be activated based on the command. A sensor network system comprising a sensor node, a base station that performs wireless communication with the sensor node, and a server connected to the base station via a network,
The sensor node is
An electronic device using a button battery as a power source,
A sensor that performs sensing;
A transmission / reception circuit for performing data transmission / reception with the base station;
A memory for storing data for setting the operation mode of the sensor node;
A control device for controlling the sensing and the data transmission / reception,
The control device estimates a consumption current necessary for the sensing based on data for setting the operation mode, and determines the timing of the sensing and the data transmission / reception based on the consumption current. A sensor network system comprising a sensor node, a base station that performs wireless communication with the sensor node, and a server connected to the base station via a network,
The sensor node is
An electronic device using a battery with a battery capacity of 200 mAh or less as a power source,
A sensor that performs sensing;
A transmission / reception circuit for performing data transmission / reception with the base station;
A memory for storing data for setting the operation mode of the sensor node;
A control device for controlling the sensing and the data transmission / reception,
The control device estimates a consumption current necessary for the sensing based on data for setting the operation mode, and determines the timing of the sensing and the data transmission / reception based on the consumption current.

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