Patent Publication Number: US-2007108840-A1

Title: Electronic controlling device and a method of controlling the same

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an electronic controlling device and a method of controlling the same. In particular, the invention relates to an electronic controlling device having such a function as to turn off the power of a system if not particularly needed to operate and to start up if receiving trigger signals through an external switch or a communication line, in accordance with any of the trigger signals, and a method of controlling the same.  
      2. Description of Related Art  
      In recent years, the electronic controlling device has proceeded toward reduction of the total power consumption by saving power consumption of incorporated semiconductor devices (IC: integrated circuits). Further, among the ICs incorporated to the electronic controlling device, ICs that need not to operate in the system are put to a power-saving mode such as a standby mode to thereby save the total power consumption of the electronic controlling device. However, in an electronic controlling device driven by a battery, the battery is discharged due to a standby current consumed in the standby mode albeit slowly, even in the standby mode. This results in a problem that a device driving period is shortened.  
      Japanese Unexamined Patent Publication No. 2003-63102 discloses a technique as a solution to the above problem.  FIG. 7  is a circuit diagram of a conventional electronic controlling device disclosed in Japanese Unexamined Patent Publication No. 2003-63102. As shown in  FIG. 7 , the conventional electronic controlling device operates while supplied with power from a battery BATT 101 , and includes switches SW 101  and SW 102 , a capacitor C 1 , resistors R 101  to R 103 , switch transistors Q 1  and Q 2 , a diode D 1 , a regulator  101 , a microcomputer  102 , and a circuit block  103 . Here, the switches SW 101  and SW 102  are SPDT switches operating in conjunction with each other.  
      First, if the switches SW 101  and SW 102  are turned OFF (terminals A and C are connected together), charges are accumulated in the capacitor C 1  through charging of the battery BATT 101 . Further, a gate of the switch transistor Q 1  is connected to a positive terminal of the battery BATT 101  through the resistor R 101 , so the switch transistor Q 1  becomes nonconducting. As a result, the power supply to the regulator  101  is stopped, and the regulator  101  stops operations. Along with this, the microcomputer  102  and the circuit block  103  operating with the power VCC generated by the regulator  101  stop operations.  
      Next, description is given of the case where the switches SW 101  and SW 102  are turned ON (terminals B and C are connected together). After the switches SW 101  and SW 102  are switched from OFF to ON, the charges accumulated in the capacitor C 1  flow to the switch transistor Q 2  through the resistor R 102 . As a result, the switch transistor Q 2  becomes conducting, and a voltage of a gate of the switch transistor Q 1  is lowered. Thus, the switch transistor Q 1  becomes conducting. After the switch transistor Q 1  becomes conducting, power is supplied to the regulator  101  from the battery BATT 101 , and the regulator  101  generates the power VCC. The microcomputer  102  and the circuit block  103  operate based on the power VCC. In this example, if the circuit block  103  stops operating for a predetermined period or longer, the microcomputer  102  sets a voltage of the power supply control port to a low level (for example, ground voltage). The power supply control port is connected to a base of the switch transistor Q 2  through the diode D 1 . That is, the switch transistor Q 2  becomes nonconducting if the voltage of the power supply control port is shifted to a low level. In this way, the gate voltage of the switch transistor Q 1  is equal to the voltage of the battery BATT  101 , so the switch transistor Q 1  becomes nonconducting. If the switch transistor Q 1  becomes nonconducting, power supply to the regulator  101  is stopped, and thus power supply to the microcomputer  102  and the circuit block  103  connected with the regulator  101  is stopped.  
      That is, the conventional electronic controlling device as disclosed in Japanese Unexamined Patent Publication No. 2003-63102 sets the switch transistor Q 1  conducting to supply power to the electronic controlling device from the regulator in the case of operating the electronic controlling device. Further, if the electronic controlling device stops operating over a predetermined period, the switch transistor Q 1  is set nonconducting to thereby stop the power supply to the electronic controlling device. Hence, if the electronic controlling device stops operating over a predetermined period or more, the total power consumption of the electronic controlling device is saved.  
      However, the conventional electronic controlling device has only one SPDT switch (switches SW 101  and SW 102 ), and thus faces a problem in that the electronic controlling device cannot be turned on in accordance with plural conditions, and operations of the electronic controlling device cannot be changed in accordance with these conditions.  
      In recent electronic controlling devices, if the power supply of a control circuit of the microcomputer is turned off, it is necessary to switch operations and activate the circuit in accordance with where a control signal is input, in some cases. Especially in a control circuit that has a communication terminal and needs to start operations in accordance with a signal from a communication line, in order to detect the signal from the communication line, the control circuit realizes a signal-waiting mode and a power-saving mode by utilizing a standby function that stops only internal operations while the power is being supplied. In other words, in the conventional electronic controlling device, the power supply to the microcomputer cannot be stopped for activating the electronic controlling device in accordance with a signal from the communication line. Therefore, in the case where the electronic controlling device is activated in accordance with the signal from the communication line, a standby current is consumed even in a non-operating period.  
     SUMMARY OF THE INVENTION  
      An electronic controlling device according to an aspect of the present invention includes: a power supply control circuit generating a second power based on a first power in response to input of a first trigger signal or a second trigger signal; and a device control circuit operating based on the second power, operating in a first operating mode if activated in accordance with the first trigger signal, operating in a second operating mode if activated in accordance with the second trigger signal, and outputting a shutdown signal to stop generation of the second power with the power supply control circuit after a predetermined operation in the first operating mode or the second operating mode.  
      According to another aspect of the invention, a method of controlling an electronic controlling device including a power supply control circuit generating a second power based on a first power, and a device control circuit operating based on the second power, includes: generating the second power with the power supply control circuit in response to input of a first trigger signal or a second trigger signal; and causing the electronic controlling device to operate in a first operating mode if activated in accordance with the first trigger signal, operate in a second operating mode if activated in accordance with the second trigger signal, and output a shutdown signal to stop generation of the second power with the power supply control circuit after a predetermined operation in the first operating mode or the second operating mode.  
      According to the electronic controlling device of the present invention, the power supply control circuit can be activated in accordance with one of the first trigger signal and the second trigger signal to generate the second power and operate the device control circuit (for example, microcomputer) based on the second power. For example, provided that the first trigger signal is a trigger signal from the external switch, and the second trigger signal is a trigger signal from the communication line, even in the case of stopping power supply to the microcomputer during such a period that the electronic controlling device stops operating, the microcomputer can be activated in accordance with the trigger signal from the communication line. Therefore, according to the electronic controlling device of the present invention, even in the case of activating the electronic controlling device in accordance with the trigger signal from the communication line, the power supply to the microcomputer can be stopped, making it possible to save power consumption when the electronic controlling device is not operating.  
      Further, according to the electronic controlling device of the present invention, the first operating mode and the second operating mode can be switched in accordance with a trigger signal. That is, only requisite blocks out of functional blocks of the electronic controlling device can be selectively operated based on a type of the trigger signal. Thus, the electronic controlling device of the present invention can be activated while putting unused functional blocks in a power-saving mode (for example, standby mode), whereby power wasted by blocks unnecessary for target operations can be saved even under operating conditions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects, advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a block diagram of a door module system according to a first embodiment of the present invention;  
       FIG. 2  is a block diagram of a door module of the first embodiment;  
       FIG. 3  is a flowchart of activating and initializing procedures of the door module of the first embodiment;  
       FIG. 4  is a flowchart of operations of the door module of the first embodiment;  
       FIG. 5  is a flowchart of operations of a power supply circuit of the first embodiment;  
       FIG. 6  shows how the door module of the first embodiment shifts a mode and consumes power; and  
       FIG. 7  is a circuit diagram of a conventional electronic controlling device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The invention will be now described herein with reference to illustrative embodiments. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the invention is not limited to the embodiments illustrated for explanatory purposed.  
      Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings. In this embodiment, description is given of a control module (for example, door module) incorporated in an automobile as an electronic controlling device example. The door module is provided to each of doors of the automobile, and used to control the locking/unlocking of the doors or the opening/closing of windows, for example. Further, the door modules are connected through a communication line in the automobile body.  FIG. 1  is a block diagram of the door module system.  
      As shown in  FIG. 1 , a door module system of this embodiment has four doors on the front and rear, and right and left sides. The door module system includes door modules  1  to  4 , and a body module  5 . The door modules  1  to  4  are provided on a passenger-side (front left), a driver&#39;s-side (front right), a left-handed backseat (rear left), and a right-handed backseat (rear right), respectively, to control the respective doors in accordance with signals from a corresponding external switch or communication line. The body module  5  executes control on the automobile body, for example.  
      The door modules  1  to  4  and the body module are connected via a communication line in the automobile body. Through the communication line in the automobile body, a predetermined module sends/receives a control signal to/from another module.  
      Here, an operation of the door module is described taking the passenger-side door module  1  as an example. The door module  1  has a first operating mode (switch-induced operating mode) where a user (driver or passenger) manipulates a switch directly connected with the door module  1 , and the door module  1  operates in accordance with the manipulation, and a second operating mode (communication-induced operating mode) where the door module  1  receives control data from another module to thereby operate.  
      Regarding the control in the switch-induced operating mode, the passenger-side door is controlled based on a signal from the switch directly connected with the door module  1 . This control is executed over, for example, a window lift mechanism for opening/closing a window, a window lock mechanism for locking the window, and a door lock mechanism for locking/unlocking a door.  
      Incidentally, the switch-induced operating mode may include a mode where the door module  1  sends control data to another module in accordance with the manipulation of the switch directly connected with the door module  1 .  
      Regarding the control in the communication-induced operating mode, the passenger-side door is controlled in accordance with a control signal sent from another module to the door module  1 . This control includes, for example, side mirror control for adjusting the angle of side mirrors and switch locking control for disabling a switch provided to a door, in addition to the control on the window lift mechanism, the window lock mechanism, and the door lock mechanism in accordance with a control signal sent from, for example, the driver&#39;s-side door module  2 .  
      In this example, the door module  1  can operate with a local control function alone, in the switch-induced operating mode. On the other hand, the door module  1  can operate with a network control function alone, in the communication-induced operating mode.  
      Hence, the door module  1  changes the function depending on which mode is selected. Thus, power consumption can be saved even under operating conditions, by putting a circuit of an unused function into a standby state.  FIG. 2  is a block diagram of the door module  1  and is referenced to detail the door module  1 .  
      As shown in  FIG. 2 , the door module  1  includes a power supply control circuit  1   a , a device control circuit  1   b , an external switch  1   c , and a communication line  1   d.    
      The power supply control circuit  1   a  operates in accordance with a first power (for example, battery voltage Vbat) and is being supplied with a power as long as connected with a battery. Further, the power supply control circuit  1   a  generates a second power (for example, power supply voltage VDD) in accordance with a first trigger signal (for example, switch-induced operation signal SG 1 ) or a second trigger signal (for example, communication-induced operation signal SG 3 ) input from the external switch  1   c , and stops generation of the power supply voltage VDD in accordance with a shutdown signal SG 7  input from the device control circuit  1   b . The power supply control circuit  1   a  is described below in more detail. The power supply control circuit  1   a  includes a first control circuit (for example, wake-up control circuit  10 ), a second control circuit (for example, operation control circuit  20 ), a power supply circuit  30 , and a transceiver  40 .  
      The wake-up control circuit  10  includes a switch edge detector  11 , a communication edge detector  12 , and an OR circuit  13 . The switch edge detector  11  detects a rising edge of the switch-induced operation signal SG 1  from the external switch  1   c , for example, to output a switch edge detection signal SG 2 . Further, in the case of detecting a rising edge of the switch-induced operation signal SG 1 , the switch edge detector  11  sends a first trigger notification signal (for example, switch-induced operation notification signal SG 1 ′) to a switch input circuit  52  as described later. Here, the external switch  1   c  is, for example, a door controlling switch directly connected with the door module  1 , and has terminals A, B, and C. The switch is shifted between a state (ON state) where the terminals A and C are connected and a state (OFF state) where the terminals B and C are connected. Further, a resistor R 1  is connected between the terminal A and the battery, and a resistor R 2  is connected between the terminal B and the ground voltage.  
      The communication edge detector  12  detects, for example, a rising edge of the communication-induced operation signal SG 3  input through the communication line  1   d  to output a communication edge detection signal SG 4 . Further, in the case of detecting the rising edge of the communication-induced operation signal SG 3 , the communication edge detector  12  sends a second trigger notification signal (for example, communication-induced operation notification signal SG 3 ′) to a communication input/output circuit  53  as described later. The OR circuit  13  outputs a wake-up signal SG 5  when receiving either the switch edge detection signal SG 2  or the communication edge detection signal SG 4 . That is, the wake-up control circuit  10  outputs a wake-up signal SG 5  if either the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  is input.  
      The operation control circuit  20  sends an operation switching signal SG 8  for switching a state of the power supply circuit  30  between an operating state and a suspend state in accordance with the wake-up signal SG 5  and the shutdown signal SG 7  output from the pulse detector  51 . In this embodiment, the operation control circuit  20  includes a set/reset latch (SR latch)  21 . When a rising edge of a signal is detected at a set (S) terminal, for example, the SR latch  21  outputs a high-level signal (for example, battery voltage Vbat). When a rising edge of a signal is detected at a reset (R) terminal, for example, the SR latch  21  outputs a low-level signal (for example, ground voltage). In this embodiment, the shutdown signal SG 7  is input to the set (S) terminal of the SR latch  21 , and the wake-up signal SG 5  is input to the reset (R) terminal. Detailed description about the shutdown signal SG 7  is given below.  
      The power supply circuit  30  is connected with the battery to generate a power supply voltage VDD as a stepped-down voltage of the battery voltage Vbat. Further, the power supply circuit  30  switches between an operating state and a suspend state in accordance with the operation switching signal SG 8  from a second control circuit (for example, operation control circuit  20 ).  
      The power supply circuit  30  includes a constant current source  31 , a reference voltage generator  32 , an amplifier  33 , a dropper  34 , and resistors R 3  and R 4 . The constant current source  31  operates based on the battery voltage Vbat and switches between an operating state and a suspend state in accordance with the operation switching signal SG 8 . The reference voltage generator  32  generates a reference voltage at a predetermined level, and switches between an operating state and a suspend state in accordance with the operation switching signal SG 8 . The amplifier  33  operates in accordance with a current supplied from the constant current source  31 . Further, a positive terminal of the amplifier  33  is connected with a reference voltage generator  32 . A resistor R 4  is connected between a negative terminal and the ground voltage. The resistor R 3  is connected between the negative terminal and an output terminal of the power supply circuit  30 . An output terminal of the amplifier  33  is connected with a gate of a dropper  34 . That is, the power supply circuit  30  amplifies the reference voltage in accordance with a resistance ratio between the resistor R 3  and the resistor R 4  to output the amplified voltage as the power supply voltage VDD. In this example, the dropper  34  is, for example, a PMOS transistor with a source connected with the battery and a drain used as an output of the power supply circuit  30 .  
      The transceiver  40  operates in accordance with the battery voltage Vbat to transmit/receive control data through the communication line. The transceiver  40  includes a receiver  41  and a driver  42 . The transceiver  40  receives input control data with the receiver  41 , and transmits control data sent from a microcomputer  60  with the driver  42 .  
      The device control circuit  1   b  includes an interface circuit  50 , and the microcomputer  60 . The device control circuit  1   b  controls the door module  1 , and the microcomputer  60  controls functional blocks (not shown) connected with the microcomputer  60  in accordance with a signal from the external switch  1   c  or control data input through the communication line  1   d.    
      The interface circuit  50  operates in accordance with the power supply voltage VDD. The interface circuit  50  includes a pulse detector  51 , a switch input circuit  52 , a communication input/output circuit  53 , and an ACT/STBY control circuit  54 . Incidentally, this embodiment describes the microcomputer  60  and the interface circuit  50  as different blocks, but the microcomputer  60  may include the interface circuit  50  or the power supply control circuit  1   a  may include the interface circuit  50 .  
      The pulse detector  51  detects the length of such a period that a pulse of a stop signal SG 6  output from the microcomputer  60  is kept at high level (for example, power supply voltage VDD). If the pulse is kept at high level for a predetermined period or longer, the pulse detector  51  outputs a shutdown signal SG 7 . Receiving the switch-induced operation notification signal SG 1 ′, the switch input circuit  52  outputs a high-level signal to the microcomputer  60  through the switch input circuit  52  after starting the device control circuit  1   b . That is, the switch input circuit  52  notifies the microcomputer  60  that the door module  1  starts operating, as the external switch  1   c  is switched from the OFF state to the ON state.  
      Receiving the communication-induced operation notification signal SG 3 ′, the communication input/output circuit  53  is a buffer that outputs a high-level signal to the microcomputer  60  through the communication input/output circuit  53  after the device control circuit  1   b  starts operating, transmits to the microcomputer communication data input through the receiver  41 , and transmits communication data from the microcomputer  60  to the driver  42 . The ACT/STBY control circuit  54  puts the communication input/output circuit  53  into a standby mode to an operating mode based on an ACT/STBY control signal SG 9  from the microcomputer. For example, if the door module  1  is activated in accordance with the switch-induced operation signal SG 1 , and thus there is no need to execute communications, the communication input/output circuit  53  is put in the standby mode. Further, when the door module  1  starts operating in accordance with the switch-induced operation signal SG 1 , and communication is required, or the door module  1  starts operating in accordance with the communication-induced operation signal SG 3 , the communication input/output circuit  53  is put into the operating mode.  
      The microcomputer  60  is a circuit operating based on the power supply voltage VDD and controlling the door module  1  based on a stored program, for example. Further, the microcomputer  60  sends/receives various commands with respect to connected functional blocks (not shown). The microcomputer  60  includes ports  1  to  4 .  
      If the microcomputer  60  meets a condition of shifting an operational mode to a power-saving mode, for example, the stop signal SG 6  is output from the port  1 . The condition of shifting to the power-saving mode is such a condition that the microcomputer  60  could be put into a suspend state, for example, an operation is completed based on the external switch  1   c  or control data, or an operation is suspended for a predetermined period or longer. The port  2  receives an output signal from the switch input circuit  52 . If this port is applied with a high-level signal, the microcomputer  60  operates in the switch-induced operating mode. The port  3  is connected with the communication input/output circuit  53 . For example, if this port receives a high-level signal from the communication input/output circuit  53 , the microcomputer  60  operates in the communication-induced operating mode. Further, if control data is received through the communication line  1   d , the microcomputer  60  operates based on the communication data. In the case of sending control data, the control data is sent from the port  3  to the communication input/output circuit  53 . The port  4  sends the ACT/STBY control signal SG 9  to the ACT/STBY control circuit  54  in accordance with the type of control.  
      The door module  1  of this embodiment is described below in detail. When a battery is mounted to an automobile, the door module  1  operates while being supplied with power from the battery. For example, the door module  1  starts initialization just at a point in time when the battery is mounted to start supplying power, and is then put on standby to wait for the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  to input. If either signal is input, the door module  1  is started to control the door.  FIG. 3  is a flowchart of initialization of the door module  1 .  FIG. 4  is a flowchart of operations from the standby state to the reception of the signal and control of the door.  
      First, the initialization of the door module  1  is described with reference to  FIG. 3 . As shown in  FIG. 3 , when the battery is mounted to the automobile, the battery voltage Vbat is supplied. Thus, the power supply circuit  30  starts operating (step S 1 ), and the microcomputer  60  is supplied with power to thereby operate the microcomputer  60  (step S 2 ). When the microcomputer  60  operates, the communication input/output circuit  53  enters the operating mode for operation confirmation (step S 3 ).  
      Through steps S 1  to S 3 , blocks of the door module  1  can operate, and then the door module  1  starts initialization (step S 4 ). The initialization makes it possible to set which edge of the rising edge and the falling edge is detected by the switch edge detector  11 , for example. In this embodiment, the circuit is set to detect the rising edge.  
      After the initialization of the door module  1  is completed in step S 4 , the door module  1  can perform a normal operation in accordance with control data received through the external switch  1   c  or the communication line  1   d  (step S 5 ). After that, the microcomputer  60  brings the communication input/output circuit  53  to a standby mode to put the door module on standby (step S 6 ). Subsequently, the microcomputer  60  outputs the stop signal SG 6  (step S 7 ). As a result, the shutdown signal SG 7  is input to the SR latch  21  of the operation control circuit  20 , so the operation switching signal SG 8  is set at low level and held (step S 8 ). If the operation switching signal SG 8  is at low level, the output of the power supply circuit  30  is stopped (step S 9 ). When the output of the power supply circuit  30  is stopped, the supply of the power supply voltage VDD is stopped, so the microcomputer  60  and the interface circuit  50  are stopped (step S 10 ). Hence, the door module  1  is put on standby to wait for the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  to input (step S 11 ).  
      Next, the normal operation of the door module  1  is explained with reference to  FIG. 4 . The door module  1  is put on standby to wait for the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  to input (step S 11 ). Here, if the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  is input, the wake-up control circuit  10  sends the wake-up signal SG 5  (step S 12 ). Thus, the SR latch  21  of the operation control circuit  20  is reset to switch the operation switching signal SG 8  from a low level to a high level (step S 13 ).  
      In step S 13 , the power supply circuit  30  is brought into an operating state and thus, outputs the power supply voltage VDD (step S 14 ). Sequentially, the microcomputer  60  operates based on the power supply voltage VDD (step S 15 ). Here, the microcomputer  60  determines a factor that starts operations to select the switch-induced operating mode or the communication-induced operating mode (step S 16 ). This determination is carried out based on the switch-induced operation notification signal SG 1 ′ in accordance with a level of a signal output from the switch input circuit  52  or based on the communication-induced operation notification signal SG 3 ′ in accordance with a level of a signal output from the communication input/output circuit  53 . For example, if the switch input circuit  52  outputs a high-level signal, the door module  1  is put into the switch-induced operating mode. If the communication input/output circuit  53  outputs a high-level signal, the door module  1  is put into the communication-induced operating mode.  
      First, operations in the switch-induced operating mode are described. In the switch-induced operating mode, the communication input/output circuit  53  does not need to operate, the communication input/output circuit  53  is held in the standby mode. Subsequently, the microcomputer  60  controls the door module  1  based on control data of the external switch  1   c  (step S 17 ). After the completion of controlling the door module  1 , the microcomputer  60  shifts the door module  1  to the standby state (step S 18 ). Subsequently, the microcomputer  60  outputs the stop signal SG 6 . The pulse detector  51  outputs the shutdown signal SG 7  based on the stop signal SG 6 , and the shutdown signal SG 7  is held in the SR latch  21  (step S 19 ). Thus, the SR latch  21  sets the operation switching signal SG 8  to a low level, and then the power supply circuit is thereby stopped (step S 20 ). By stopping the supply of the power supply voltage VDD, the microcomputer  60  and the interface circuit  50  are stopped (step S 21 ). Through the operations in steps S 19  to S 21 , the door module  1  is put on standby. Further, this standby state is the standby state of step S 11 . Incidentally, in the operation of step S 17 , even in the switch-induced operating mode, the communication input/output circuit  53  may operate to send control data to another module through the communication line.  
      Next, operations of the communication-induced operating mode are described. In the communication-induced operating mode, the communication input/output circuit  53  needs to operate, so the microcomputer  60  shifts the communication input/output circuit  53  to the operating mode (step S 22 ). Next, the microcomputer  60  receives control data from the communication line  1   d  through the receiver  41  and the communication input/output circuit  53 , and controls the door module  1  based on the control data (step S 23 ). If completing the control over the door module  1  or detecting that another door module is designated by the control data, the microcomputer  60  puts the door module  1  on standby (step S 24 ). Further, if the control data includes information suggesting a standby state, the door module  1  may be shifted to a standby state.  
      The shift of the door module  1  to the standby state is described next. First, the microcomputer  60  outputs the ACT/STBY control signal SG 9  to put communication input/output circuit  53  on standby (step S 25 ). Subsequent operations are similar to the aforementioned operations in steps S 20  to S 22 .  
      Hereinafter, detailed description is given of the operation of the power supply circuit  30 .  FIG. 5  is a flowchart of operations of the power supply circuit  30 . As shown in  FIG. 5 , when the power supply circuit  30  is applied with the battery voltage Vbat (step S 1 ), the constant current source  31  and the reference voltage generator  32  operate (step S 26 ). As a result, the power supply circuit  30  is put into an operating state to start regulation (output the power supply voltage VDD) (step S 27 ). The microcomputer  60  and the interface circuit  50  operate thereby (step S 28 ). Subsequently, the microcomputer  60  decides to put the door module  1  on standby (step S 29 ), and then the microcomputer  60  outputs the stop signal SG 6 . Based on the stop signal SG 6 , the pulse detector  51  outputs the shutdown signal SG 7 , and the output voltage of the SR latch  21  is shifted from a high level to low level (step S 30 ).  
      Due to an operation of step S 35 , the operation switching signal SG 8  is switched to a low level, so the reference voltage generator  32  and constant current source  31  of the power supply circuit  30  are stopped (step S 31 ) The power supply circuit  30  stops regulation (step S 32 ). After that, the SR latch  21  holds the shutdown signal SG 7  (step S 33 ), and the input of the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3  is waited (step S 34 ). That is, the state of steps S 38  and S 39  is the standby state of the door module  1 . Thereafter, receiving the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3 , the wake-up control circuit  10  outputs the wake-up signal SG 5  to reset the SR latch  21  and switch the operation switching signal SG 8  to a high level (step S 31 ). Accordingly, the power supply circuit  30  returns back to the operation of step S 26 .  
      As understood from the above description, the door module  1  of this embodiment activates the power supply circuit  30  to generate the power supply voltage VDD in the case of receiving either the switch-induced operation signal SG 1  or the communication-induced operation signal SG 3 , by which the microcomputer  60  and the interface circuit  50  are activated to operate the door module  1 . Further, the operation of the door module  1  can be changed in accordance with which of the switch-induced operation signal SG 1  and the communication-induced operation signal SG 3  is used to start the door module  1 . In this embodiment, if the door module  1  is driven in the switch-induced operating mode based on the switch-induced operation signal SG 1 , the door module  1  starts operating while the communication input/output circuit  53  is put on standby. In contrast, if the door module  1  is driven in the communication-induced operating mode based on the communication-induced operation signal SG 3 , the door module  1  starts operating while the communication input/output circuit  53  is set to the operational mode. Hence, the door module  1  of this embodiment can put the unused communication input/output circuit  53  on standby, in the switch-induced operating mode, making it possible to save the power consumption under operating conditions.  
       FIG. 6  shows a relation between the shift of a mode of the door module  1  and the power consumption. Referring to  FIG. 6 , the relation between the shift of a mode of the door module  1  and the power consumption is described below. Supplied with the battery voltage Vbat, the door module  1  starts operating in the switch-induced operating mode, and is then shifted to the communication-induced operating mode for initialization and then to the standby mode.  
      After the completion of the initialization, its state is shifted based on the switch-induced operation signal SG 1 , the communication-induced operation signal SG 3 , the shutdown signal SG 7 , and the ACT/STBY control signal SG 9 . To describe consumed power in each mode of the door module  1 , as shown in  FIG. 6 , the power consumption is largest in the communication-induced operating mode, followed by the switch-induced operating mode and the standby mode in this order. Regarding a conventional electronic controlling device, the device can only operate with the standby mode and a mode similar to the communication-induced operating mode of this embodiment. Thus, during the operation in the switch-induced operating mode of this embodiment, the communication input/output circuit  53  waists the power.  
      To mention power consumption of an electronic controlling device, for example, as for a conventional electronic controlling device including a power supply circuit that cannot stop operations, all blocks are operating in an operating mode, consumed power is several tens of mA. In a standby mode, a microcomputer and a communication input/output circuit are put on standby, so the two blocks each consume power of several tens of μA. In contrast, as for the door module  1  of the present invention, all blocks are operating while consuming power of several tens of mA in the communication-induced operating mode. In the switch-induced operating mode, the power consumed by the communication input/output circuit  53  can be reduced from several mA to several tens of μA. Further, in the standby mode, an operation of the power supply circuit  30  can be stopped, so the power consumption of the microcomputer and the communication input/output circuit  53  can be reduced to 0A.  
      In summary, according to the door module  1  of the present invention, even in the case of operating the microcomputer  60  in accordance with a signal from the communication line, a power supply control circuit for generating a power to be supplied to the microcomputer  60  can be activated in response to either the signal from the external switch  1   c  or the signal from the communication line. Thus, even if the power supply to the microcomputer  60  is stopped during such a period that the door module  1  is not operating, the microcomputer  60  can be driven in accordance with a signal from the communication line. Therefore, the power consumption during a period where the door module  1  is not operating can be saved.  
      Further, according to the door module  1  of the present invention, it is possible to save power wasted in an unused circuit under operating conditions as well as power consumption in the standby state. The door module  1  or other such electronic controlling devices are effective for a system where a battery having a limited charging capacity is connected all the time, and power charged in the battery is continuously consumed like a module mounted to an automobile. In recent years, a number of modules are mounted to an automobile. A power saving effect of the electronic controlling device of the present invention is particularly large in such a case.  
      Incidentally, as another embodiment of the present invention, although the two signals, the signal from the external switch and the signal from the communication line, are used to switch the operation after the start-up in the above embodiment, such signals are not limited to two types, and two or more types of signals may be used. Further, in the above description, the switch  1   c  of the present invention is a single switch. However, it is possible to provide plural switches and activate the power supply control circuit  1   a  based on a signal from any of the switches. In addition, although not particularly described in the above embodiment, the power supply control circuit and the device control circuit may be combined on a single chip as a semiconductor integrated circuit or embedded to different chips.  
      It is apparent that the present invention is not limited to the above embodiment that may be modified and changed without departing from the scope and spirit of the invention.