JP2009148071A - Electronic control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic control device for attaining lower power consumption. <P>SOLUTION: This electronic control device includes a power supply switch circuit before a power voltage Vos which is always output from a power circuit is supplied to a timer IC and is configured such that the power supply switch circuit is turned on or off by operation from a microcomputer to control supply/shut-down of electric power to the timer IC. Even if the power supply switch circuit shuts down power supply to the microcomputer and an on or off request to the power supply switch circuit is not output from the microcomputer, the power supply switch circuit continuously maintains an on or off state by a self-feedback voltage in the power supply switch circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic control device including a microcomputer, for example, an electronic control device that measures a power supply stop time to a microcomputer and supplies power to a timer circuit that restarts the microcomputer when the time reaches a set value. .

  For example, in an electronic control device that controls a vehicle engine or the like, when a secondary power supply circuit that constantly outputs a constant power supply voltage Vos based on battery power and a vehicle ignition switch that is not always on are turned on. A main power supply circuit that outputs a constant power supply voltage Vom based on the power of the battery is provided.

  The power supply voltage Vom from the main power supply circuit is supplied to a microcomputer or the like with large power consumption, and the power supply voltage Vos from the sub power supply circuit is much higher than that of a microcomputer or the like even though it must always operate. It is supplied to a small circuit or memory (so-called backup RAM).

  In particular, in this type of electronic control device, the time during which the microcomputer stops operating (in other words, the power supply voltage Vom is output from the main power supply circuit) by the timer circuit operated by the power supply voltage Vos from the sub power supply circuit. In some cases, the timer circuit outputs a power supply voltage Vom from the main power supply circuit and starts the microcomputer when the measurement time reaches a predetermined set time. .

  By providing such a timer circuit, it is possible to carry out a desired process when a set time elapses after the ignition switch is turned off even if the microcomputer is not constantly operated. Power consumption can be reduced.

  More specifically, the following operations (a) and (b) are executed.

(A) The main power supply circuit outputs the power supply voltage Vom when either the switch signal corresponding to the on / off of the ignition switch or the operation command signal generated inside the electronic control device is at the active level. Composed.

(B) The timer circuit starts counting when its count value is initialized by the microcomputer and when the ignition switch is turned off, receives a target set value and a count start command from the initial value from the microcomputer. Thereafter, the microcomputer performs self-shutoff (self-power-off) control, and stops the supply of power supply voltage to the microcomputer. When the count value reaches the set value corresponding to the set time, the timer circuit activates the microcomputer by setting the operation command signal to the main power supply circuit to the active level and outputting the power supply voltage Vom from the main power supply circuit. Let

  By the way, as an electronic control that requires such a timer circuit, for example, there is one that performs a diagnosis of an evaporation purge system (hereinafter referred to as an evaporation diagnosis) as described in Patent Document 1. In this evaporation diagnosis, for example, the system for recovering the evaporation gas (evaporation gas generated from the fuel tank) of the engine is closed and pressurized or depressurized, and the pressure fluctuation in the system is measured. By detecting, the tightness of the system is inspected.

  However, immediately after the engine is operated for a long time in a high load state, the fuel in the fuel tank is likely to evaporate, and it is difficult to obtain an accurate inspection result. For this reason, when a certain period of time has elapsed since the engine stopped, the microcomputer performs the airtightness inspection of the evaporation purge system as described above.

  However, in such a case, if the microcomputer always operates even when the engine is stopped (that is, when the ignition switch is turned off) and measures the above-mentioned fixed time, the power consumption at the time of ignition off cannot be suppressed, and the battery runs out. Will be invited.

  Therefore, when the ignition switch is turned off, the supply of the power supply voltage Vom from the main power supply circuit to the microcomputer is stopped. Thereafter, the timer circuit measures the microcomputer stop time, and the measurement time is the above-mentioned time. When a predetermined time is reached, the timer circuit outputs the power supply voltage Vom from the main power supply circuit and starts the microcomputer.

JP 2003-139874 A

  However, in the conventional vehicular electronic control device provided with the timer circuit, the power of the timer circuit is supplied from the power supply voltage Vos of the auxiliary power feeding means that always outputs, and the condition for shifting to the evaporation diagnosis is not satisfied, When timer circuit operation is not required, or when timer measurement is completed, the evaporation diagnosis process is completed, and the state just waits for the next start by the ignition switch (so-called operation request to the timer circuit is unnecessary) Even in such a case, the timer circuit consumes power, and unnecessary power is consumed. For this reason, there is a need for further power saving.

  The present invention has been made in view of such a situation, and provides an electronic control device capable of realizing further reduction in power consumption.

  In order to solve the above problems, an electronic control device according to the present invention has a configuration including a power supply switch circuit before supplying a power supply voltage Vos constantly output from a power supply circuit to a timer IC. The power supply switch circuit is controlled to be turned on or off by an operation from a microcomputer to control power supply to the timer IC. The power supply switch circuit is turned on or off by the self-feedback voltage in the power supply switch circuit even when the power supply to the microcomputer is cut off and no on or off request is output from the microcomputer to the power supply switch circuit. It is possible to continue to maintain this state.

  That is, an electronic control device according to the present invention includes a power supply unit that outputs a main power supply voltage and a sub power supply voltage, a microcomputer that operates according to the main power supply voltage, a timer circuit that includes a time counter that operates according to the sub power supply voltage, and a timer circuit. A power supply switch for executing and cutting off the supply of the sub power supply voltage to the power supply. Then, the timer circuit measures the elapsed time with the time counter, and when the count value of the time counter reaches a predetermined value, sets the power supply start signal for starting the microcomputer to an active level. The power supply means outputs the main power supply voltage in response to the power supply activation signal. Further, the microcomputer detects a state in which the supply of the sub power supply voltage to the timer circuit is unnecessary, controls the power supply switch based on the detection result, and interrupts the supply of the sub power supply voltage to the timer circuit.

  The electronic control device further includes state maintaining means (generation of a self-feedback voltage) that continues the power supply switch to the connected state or the disconnected state even when the supply of the main power supply voltage to the microcomputer is interrupted.

  The timer circuit has a low voltage detection function for detecting that the timer circuit is in a low voltage operation state when the timer circuit is operating at a low voltage. When the timer circuit is undiagnosed, the microcomputer controls the power supply switch to forcibly cut off the supply of the sub power supply voltage to the timer circuit. Diagnose if it works.

  The microcomputer has a function to monitor the communication status with the timer circuit. When there is a problem with the communication status with the timer circuit, the microcomputer controls the power supply switch and shuts off the sub power supply voltage supply to the timer circuit for a certain period. Thereafter, the timer circuit is reset and returned to the initial state by reconnecting.

  The power supply unit may be configured as a power supply IC, and a power supply switch may be built in the power supply IC.

  Further features of the present invention will become apparent from the best mode for carrying out the present invention and the accompanying drawings.

  According to the electronic control device of the present invention, further reduction in power consumption can be realized.

  The embodiment according to the present invention solves the following problems in addition to providing an electronic control device that realizes further reduction in power consumption. That is, some timer ICs have a low voltage detection function. If the timer IC detects a low voltage, the counter may not be operating correctly. For this reason, even when the microcomputer IC is started by setting the power supply start signal to the active level and outputting the power supply voltage Vom from the main power supply means when the measurement time of the timer IC reaches a predetermined set time, the timer IC is low. When the voltage is detected, it is determined that the measured time is not correct and the desired control is not performed. If this low voltage detection function does not function correctly, there is a risk of starting control at the wrong time. Also, in the past, if some trouble occurred in the timer circuit and it was not possible to recover due to operation from the microcomputer, remove the battery or disconnect the connector of the electronic control unit and shut off the power supply once Then, it was necessary to reset the timer IC again.

  Therefore, the present embodiment also provides means for performing diagnosis of the low voltage detection function and for recovering when the timer IC malfunctions (so-called reset).

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be noted that this embodiment is merely an example for realizing the present invention, and does not limit the technical scope of the present invention. In each drawing, the same reference numerals are assigned to common components. In addition, the electronic control apparatus of embodiment described below assumes what mainly controls the engine of a vehicle.

<First Embodiment>
(1) Configuration of Electronic Control Device FIG. 1 is a diagram showing a schematic configuration of an electronic control device (engine control unit) according to a first embodiment of the present invention. As shown in FIG. 1, the electronic control unit 100 includes a microcomputer 7 that executes various processes for engine control, a timer IC 10 that measures the time during which the microcomputer 7 has stopped operating, and an electronic control unit 100. A power supply IC 6 for generating power, a power supply switch circuit 8 for on / off control of power supply from the power supply IC 6 to the timer IC 10, and a drive element 5 for driving the load 3 to be controlled by the electronic control unit 100. I have.

  In the electronic control unit 100, the battery voltage VB of the vehicle is always supplied to the SUB of the power supply circuit 6. Then, the SUB of the power supply IC 6 always generates and outputs the power supply voltage Vos from the battery voltage VB. The power supply voltage Vos is supplied to a circuit (power consumption is always required), a memory (so-called backup RAM), etc. whose power consumption is much smaller than that of a microcomputer or the like. The power supply Vt of the timer IC 10 is configured such that the power supply voltage Vos is supplied / cut off via the power supply switch circuit 8. Supply / cutoff of the power supply voltage Vos is controlled by an on signal Son (on at high level) and an off signal Soff (off at high level) from the microcomputer 7. The power supply switch circuit 8 is turned on or off by the self-feedback voltage 9 even when the supply of the main power supply voltage Vom to the microcomputer 7 is stopped and the control signal (Son / Soff) from the microcomputer 7 is not output. It is configured to be able to continue to maintain this state.

  On the other hand, the MAIN (Vig) of the power supply IC 6 is output from the microcomputer 7 when the vehicle ignition switch 2 (hereinafter referred to as IGSW) is turned on, when the power activation signal Sal output from the timer IC 10 is at a high level, and from the microcomputer 7. The battery voltage VB is supplied when at least one of the cases where the power holding signal Smr is at a high level is established. Then, the power supply IC 6 generates a power supply voltage Vom from the MAIN of the power supply IC 6 and outputs it.

  More specifically, first, an ignition switch signal Sig indicating the on / off state of the IGSW 2 is input to the electronic control device 100 via the IGSW 2. Note that the ignition switch signal Sig becomes a high level when the IGSW 2 is turned on, and becomes a low level when the IGSW 2 is turned off.

  Further, the battery voltage VB is supplied to VIG through the contact of the power supply relay 4 provided outside the electronic control device 100 to the MAIN of the power supply circuit 6. The electronic control unit 100 supplies the power when at least one of the ignition switch signal Sig, the power activation signal Sal from the timer IC 10 and the power holding signal Smr from the microcomputer 7 is at a high level. A drive circuit 11 for energizing the coil of the relay 4 to short-circuit (turn on) the contact of the relay 4 and an OR circuit 12 for outputting a signal to the drive circuit 11 are provided.

  Therefore, when any of the ignition switch signal Sig, the power activation signal Sal from the timer IC 10, and the power holding signal Smr from the microcomputer 7 is at a high level, the output So11 of the OR circuit 12 is at a high level. Then, the drive circuit 11 is turned on, then the power supply relay 4 is turned on, the battery voltage VB is supplied to the MAIN of the power supply IC 6, and the power supply voltage Vom is output from the MAIN of the power supply IC 6. In the present embodiment, the logic level of each signal Sig, Sal, Smr is the active level at the high level and the passive level at the opposite low level.

  Further, the electronic control device 100 has a so-called power-on reset function that outputs a reset signal (RES) to the microcomputer 7 for a very short time when the power supply voltage Vom is considered to be stable at the start of output of the power supply voltage Vom from the power supply IC 6. I have. For this reason, the microcomputer 7 starts operation (that is, starts) from the initial state when the MAIN of the power supply IC 6 starts outputting the power supply voltage Vom.

  In the electronic control device 100, when the operation starts upon receiving the power supply voltage Vom from the power supply IC 6, the microcomputer 7 sets the power holding signal Smr to the OR circuit 12 to the high level and the power supply voltage Vom from the power supply IC 6 is output. (That is, a state in which the microcomputer 7 is operable). When the microcomputer 7 determines that a predetermined operation stop condition for the microcomputer 7 (IGSW2 is OFF and the processing at the time of OFF (various processes executed after the IGSW2 is turned off) is completed), the microcomputer 7 holds the power supply. The signal Smr is set to a low level to stop the supply of the power supply voltage Vom from the power supply IC 6, thereby stopping its own operation. In the present embodiment, the operation stop condition is that the microcomputer 7 is turned on when the IGSW 2 is turned on (in other words, when the ignition switch signal Sig is changed to the high level), the IGSW 2 is turned off. The above operation stop condition is satisfied when necessary processing is completed (power supply is stopped when the ignition switch is turned off). Further, when the microcomputer 7 is activated when the power supply activation signal Sal from the timer IC 10 becomes high level while the IGSW 2 is turned off, the load 3 is driven by a specific process required at that time, for example, the drive element 5. The operation stop condition is satisfied at the time when the operation such as performing the operation is completed (power supply stop when the specific control process ends).

  Here, there is no need to supply power to the timer IC 10 in the following cases when performing the evaporation diagnosis.

  The first case is a case where the power supply is stopped by turning off the ignition switch after the end of normal engine control, because the evaporative diagnosis condition is not satisfied. For example, when the engine operation time is short and the cooling water temperature is less than the specified condition value, the diagnosis condition is not satisfied and the evaporation diagnosis is not required.

  The second case is a case where the power supply stoppage is established by the end of the specific control process, and it is determined that the evaporation diagnosis by the timer measurement is unnecessary again after the completion of the evaporation diagnosis.

  In these cases, since it is determined that the evaporation diagnosis itself is unnecessary, it is not necessary to start the microcomputer by timer measurement. That is, since it is not necessary to supply power to the timer circuit, it is possible to cut power supply and reduce power consumption.

(2) Processing Operation of Microcomputer FIG. 2 is a flowchart for explaining the entire processing executed by the microcomputer 7 (that is, the operation subject of each step is the microcomputer 7).
When the microcomputer 7 receives the power supply voltage Vom from the power supply IC 6 and starts its operation, first, in step (hereinafter simply referred to as “S”) 100, the power holding signal Smr to the OR circuit 12 is set to the high level and the power supply IC6. Is maintained in a state where the power supply voltage Vom is output.

  In subsequent S110, the microcomputer 7 monitors the state of the IGSW2, and if the ignition switch signal Sig is determined to be at the high level, it is determined that the current activation is due to the operation of the IGSW2, and the engine control routine (S120 to S120). 150).

  First, in S120, an engine start process is performed, and the process proceeds to S125 after the complete explosion of the engine. In S125, a later-described timer IC diagnosis execution result (timer IC diagnosis has been executed or not) is determined. When timer IC diagnosis FLG = 1 (timer IC diagnosis has been executed), the process proceeds to S145, where Implement injection control. Thereafter, the process proceeds to S150, and a routine of an IGSW check process described later is repeatedly executed.

  When the timer IC diagnosis FLG = 0 (timer IC diagnosis is not performed) in S125, the process proceeds to S130, and the microcomputer 7 sets the output of the microcomputer 7 as Son = HIGH and Soff = LOW, The power supply switch circuit 8 to the timer IC 10 is turned on to supply power to the timer IC 10. Next, in S135, the microcomputer 7 performs a timer IC diagnosis process and checks whether the timer IC operates normally. Details of the timer IC diagnosis processing will be described separately with reference to FIG. In S140, the microcomputer 7 sets the timer IC diagnosis FLG = 1 (timer IC diagnosis is completed), and proceeds to the ignition / injection control in S145.

  It should be added that when the evaporation diagnosis is performed, the state after the engine operation is diagnosed, so that the engine control routine with the IGSW 2 turned on is always passed.

  Next, the case where the ignition switch signal Sig = 0 (IGSW = OFF) will be described in S110 of FIG. When the IGSW 2 is activated and activated, the process proceeds to an evaporation purge system diagnosis routine (S160 to S300).

  First, in S160, the microcomputer 7 determines whether or not the power activation signal Sal from the timer IC 10 is at a high level. In the case of the high level determination, it is determined that the current activation of the microcomputer 7 is activation by the timer IC 10, and the process proceeds to S170. On the other hand, when the power activation signal Sal is at a low level, the activation factor of the microcomputer 7 cannot be specified. Therefore, the microcomputer 7 performs the fail safe process of S260 and then repeats the IGSW check process described later in S290. Execute.

  In S170, the microcomputer 7 checks the flag in the timer IC 10 and confirms that there is no abnormality in the low voltage detection flag or the like. If there is no abnormality, the process proceeds to S180. If there is an abnormality in the flag of the timer IC 10, the process proceeds to S270, and the microcomputer 7 performs a predetermined fail-safe process, and then repeatedly executes an IGSW check process, which will be described later, in S290. The fail-safe processing in S260 and S270 includes, for example, the occurrence of an abnormality and storing diagnosis information (abnormality history information) indicating the content of the abnormality in a nonvolatile memory.

  In S180, the microcomputer 7 reads the counter value of the timer IC 10 and stores the data as CNT in the RAM or the like inside the microcomputer 7. Next, in S190, the microcomputer 7 determines whether or not the count value CNT of the timer IC 10 matches the currently set value Ns. That is, it is determined whether or not the counter value when the microcomputer 7 is activated really reaches the set value Ns. If it is determined that CNT = set value Ns, the microcomputer 7 determines that the timer IC 10 is functioning normally, and performs an evaporation diagnosis process in S200. As described above, the evaporation diagnosis process closes the system for recovering the evaporated gas from the engine fuel tank, pressurizes or depressurizes, detects the pressure fluctuation in the system, and detects the system It is for checking confidentiality.

  When the evaporation diagnosis process in S200 is completed, it is determined in S210 whether the next evaporation diagnosis process is necessary. If it is determined that the next evaporation diagnosis process is necessary, the microcomputer 7 transmits and sets the next set value Ns to the timer IC 10 in S220. In S230, the microcomputer 7 transmits a “counter clear instruction” to the timer IC 10 to reset the counter value. Further, in S240, the microcomputer 7 transmits a “Sal clear instruction” to the timer IC 10 to set the power activation signal Sal from the timer IC 10 to a low level.

  In step S245, the microcomputer 7 transmits a “count start instruction” to the timer IC 10, and in step S250, the microcomputer 7 sets the power holding signal Smr from the microcomputer 7 to a low level. Then, the supply of the power supply voltage Vom from the power supply IC 6 is stopped, and the microcomputer 7 stops its operation. As the operation of the electronic control unit 100, when the timer IC count starts in S245, the count is continued until the power activation signal Sal becomes High (high level). When the power activation signal Sal is High, the microcomputer 7 is activated (Smr = High), and the process of S100 in FIG. 2 is resumed.

  If the microcomputer 7 determines in S190 that CNT = the set value Ns is not satisfied (the counter value has not reached the set value Ns), the process proceeds to S280. In S280, the microcomputer 7 determines that the signal line of the power activation signal Sal from the timer IC 10 has been shorted to the high level side, performs a predetermined fail-safe process, and then proceeds to S290, where an IGSW described later is performed. Repeat the check process. As the fail-safe process in S280, for example, diagnosis information indicating that an abnormality has occurred and the content of the abnormality is stored in a non-volatile memory, and battery occupancy may occur for a vehicle occupant. There are things such as notifying that there is sex. In other words, in this case, although the count value in the timer IC 10 has not yet reached the set value, the microcomputer 7 is activated due to a short circuit failure of the signal line of the power activation signal Sal to the high level side. This is because, after that, the output of the power supply voltage Vom from the power supply circuit 6 cannot be stopped, and the battery may be consumed.

  If it is determined in S210 that the next evaporation diagnosis is unnecessary, the process proceeds to S300. Therefore, the microcomputer 7 sets the output of the microcomputer 7 to Son = LOW and Soff = HIGH, thereby turning off the power supply switch circuit 8 to the timer IC 10 and cutting off the power supply to the timer IC 10. Thereafter, the process proceeds to S250, and the microcomputer 7 sets the power holding signal Smr from the microcomputer 7 to a low level. Then, the supply of the power supply voltage Vom from the power supply circuit 6 is stopped, and the microcomputer 7 stops its operation. In this case, the next activation factor is limited to IGSW on.

(3) Timer IC Diagnosis Processing FIG. 3 is a flowchart for explaining a detailed operation example of the timer IC diagnosis processing executed in S135 in FIG. The timer IC diagnosis process includes a low voltage detection function diagnosis process and a timer function diagnosis process.

  First, the low voltage detection function diagnosis (S600 to S660 and S790) will be described. In S600, the microcomputer 7 clears the internal flag of the timer IC 10. Next, in S610, the microcomputer 7 confirms whether or not the low voltage detection flag is cleared. If cleared, the determination is YES and the process moves to S620.

  In S620, the microcomputer 7 sets the output of the microcomputer 7 to Son = LOW and Soff = HIGH, and turns off the power supply switch circuit 8. In S630, the microcomputer 7 stops (waits) the discharge waiting time for the power supply voltage Vt of the timer IC 10 to be equal to or lower than the low voltage detection determination value. Thereafter, in S640, the output of the microcomputer 7 is set to Son = By setting HIGH, Soff = LOW and turning on the power supply switch circuit 8, the power supply voltage Vt to the timer IC 10 is supplied again. In other words, when the timer IC 10 is intentionally set to a low voltage state (S620 and S630) and power is supplied again to the timer IC 10 (S640), it is determined whether the low voltage detection function operates normally (S650). It is.

  In S650, the microcomputer 7 monitors the low voltage detection flag inside the timer IC 10, and when the low voltage detection flag is 1, the microcomputer 7 determines that it is normal, and performs timer function diagnosis after S670. If the determination result is false (NO in S610 and S650), the process proceeds to S660. And the microcomputer 7 judges that the malfunction of the low voltage flag detection abnormality of timer IC10 has arisen, and performs a predetermined fail safe process. Thereafter, the process proceeds to S790. In S790, the microcomputer 7 ends the processing with OKFLG = 0 in the microcomputer.

  Next, timer function diagnosis (S670 to S790) will be described. In S670, the microcomputer 7 clears the flag in the timer IC 10. This is because the low voltage detection function is diagnosed as normal. Thereafter, in S680, the microcomputer 7 transmits the set value Nt to the timer IC 10 and sets it. Here, since it is a setting for checking the operation of the timer, the set value Nt is not a long time of several hours, but is preferably a set value of several seconds to several minutes. Further, when determining the set value, it is desirable to set in consideration of variations in the actual measurement period.

  In S690, the microcomputer 7 transmits a “counter clear instruction” to the timer IC 10 to reset the counter value. Furthermore, in S700, the microcomputer 7 transmits a power activation signal “Sal clear instruction” to set the power activation signal Sal to a low level state. Next, the microcomputer 7 transmits a count start command to the timer IC 10 in S710, clears the microcomputer built-in timer in S720, and keeps the microcomputer built-in timer TMR until the power activation signal Sal becomes high level in S730 and S740. Add the count to. Although the microcomputer built-in timer uses an addition counter here, a subtraction counter or a free-run counter can be used as another method.

  If it is determined in S740 that Sal = High (high level), the microcomputer 7 reads the counter value of the timer IC 10 in S750, and stores the data as CNT in the RAM or the like inside the microcomputer 7. In S760, the microcomputer 7 compares the count value CNT of the timer IC 10 with the count value TMR of the microcomputer built-in timer, and determines whether or not they match. If the determination in step S760 is affirmative that CNT = TMR, the microcomputer 7 determines that the timer IC 10 is functioning normally, and in step S770, sets OKFLG = 1 in the microcomputer and ends the process. On the other hand, if a negative determination is made that CNT ≠ TMR, the microcomputer 7 determines that the timer IC 10 is abnormal, performs a predetermined fail-safe process in S780, and sets OKFLG = 0 in the microcomputer to end the process in S790.

  Even when the timer function is not normal, the ignition / injection process (S145) is executed. That is, regardless of whether OKFLG is 0 or 1, the microcomputer 7 sets FLG, which means that the diagnosis of the timer IC 10 has ended, to 1 (S140), and executes the process of S145.

(4) IGSW Check Processing FIG. 4 is a flowchart for explaining details of the IGSW check processing executed in each of S150 and S290 in FIG.
As shown in FIG. 4, when the IGSW check process is performed, first, in S400, the microcomputer 7 transmits a “Sal clear instruction” to the timer IC 10 and sets the power activation signal Sal from the timer IC 10 to a low level. To do. In S410, the microcomputer 7 determines whether or not the IGSW 2 is turned on based on the logic level of the ignition switch signal Sig. If it is determined that the IGSW 2 is turned on, the microcomputer 7 ends the IGSW check process as it is. If the microcomputer 7 determines that the IGSW 2 is not turned on (turned off), the process proceeds to S420.

  In S420, the microcomputer 7 determines whether or not the evaporation diagnosis start condition is met. If the evaporation diagnosis start condition is satisfied, the process proceeds to S430, and the microcomputer 7 determines the above-described timer IC diagnosis result (OKFLG).

  If OKFLG is 1 (timer IC diagnosis OK), the process proceeds to S440, and the microcomputer 7 transmits the counter setting value Ns to the timer IC 10 to set the counter value. In subsequent S450, the microcomputer 7 transmits a “counter clear instruction” to the timer IC 10 to reset the counter value. Further, in S460, the microcomputer 7 transmits a “count start instruction” to the timer IC 10, and in S470, sets the power holding signal Smr from the microcomputer 7 to a low level. Then, the supply of the power supply voltage Vom from the power supply circuit 6 is stopped, and the microcomputer 7 stops its operation. In this case, in the next activation, when the count value of the timer IC 10 matches the set value, the power activation signal Sal outputs a high level, and before that, the ignition switch signal Sig is turned on by turning on the IGSW2. There are two cases that occur at a high level.

  On the other hand, if it is determined in S420 that the evaporation diagnosis start condition is not satisfied or the timer IC diagnosis result OKFLG is 0 (timer IC diagnosis NG) in S430, the process proceeds to S480. In S480, the microcomputer 7 sets the output of the microcomputer 7 to Son = LOW and Soff = HIGH, thereby turning off the power supply switch circuit 8 to the timer IC 10 and shutting off the power supply to the timer IC 10. Thereafter, in S470, the microcomputer 7 sets the power holding signal Smr to a low level. Then, the supply of the power supply voltage Vom from the power supply circuit 6 is stopped, and the microcomputer 7 stops its operation. In this case, the next activation factor is limited to turning on IGSW2.

(5) Timer IC Reset Processing FIG. 5 is a flowchart for explaining processing for resetting the timer IC 10. The timer IC reset process is a process of checking the communication state between the microcomputer 7 and the timer IC 10 and resetting the timer IC 10 based on the check result.

  First, in S500, the microcomputer 7 monitors the communication response of the timer IC 10, and if there is no problem in the communication state, ends the timer IC reset process as it is. Note that the communication state is determined by, for example, the presence or absence of an acknowledgement.

  On the other hand, if the microcomputer 7 communicates with the timer IC 10 but does not receive a response from the timer IC 10 and times out, the microcomputer 7 determines that the communication is NG, and the process proceeds to S510. Transition.

  In S510, the microcomputer 7 sets the output of the microcomputer 7 to Son = LOW and Soff = HIGH, and turns off the power supply switch circuit 8. In S520, the microcomputer 7 stops (waits) the discharge waiting time for the power supply voltage Vt of the timer IC 10 to be equal to or lower than the low voltage reset determination value. In S530, the output of the microcomputer 7 is set to Son = HIGH, Soff. = LOW, and the power supply switch circuit 8 is turned on. Then, the power supply voltage Vt to the timer IC 10 is supplied again. By controlling in this way, the timer IC 10 can be initialized.

  Next, in S540, the microcomputer 7 performs communication with the timer IC 10 again and determines a communication response. In the case of communication OK, the process proceeds to S570, and the microcomputer 7 executes a predetermined fail-safe process. For example, diagnosis information indicating that a communication error has occurred in the timer IC 10 and the contents such as recovery by reset processing is stored in the nonvolatile memory. Thereafter, in S580, the microcomputer 7 transmits a “flag clear instruction” to the timer IC 10 and ends the process.

  On the other hand, in the case of communication NG in S540, the process proceeds to S550, and the microcomputer 7 performs a predetermined fail-safe process. For example, diagnosis information indicating that a communication abnormality has occurred in the timer IC 10 and contents such as the inability to recover are stored in the nonvolatile memory. Thereafter, in S560, the microcomputer 7 sets OKFLG = 0 in the microcomputer 7 and ends the process.

<Second Embodiment>
FIG. 6 is a diagram showing a schematic configuration of an electronic control device 200 according to the second embodiment of the present invention. In the present embodiment, the power supply switch circuit 8 of the timer IC 10 is configured to be built in the power supply IC 6. In this case, since the power supply switch circuit control signal Son / off from the microcomputer 7 is latched by the latch circuit 13 in the power supply IC 6, the power supply switch control signal Son / off from the microcomputer 7 is received by the microcomputer 7. A configuration that allows continuous maintenance even when stopped.

<Summary>
The present invention is applicable to a vehicle electronic control device provided with a microcomputer, but is not limited to this, and a control unit (microcomputer) that operates or stops according to a power supply state accompanying switching of a power switch, The present invention can be widely applied to electronic control devices including a timer unit (timer IC) that continuously measures time regardless of operation / stop of the control unit.

  As described above, according to the present embodiment, the power supply voltage (sub power supply voltage) Vos is always applied to the timer IC. However, when the vehicle operating state is not suitable for the evaporation diagnosis, the evaporation diagnosis control is unnecessary. As described above, the power supply to the timer IC is cut off by turning off the switch circuit after the ignition switch is turned off and before the microcomputer is turned off (self-shut off). Similarly, after the evaporative diagnosis process, if the evaporative diagnosis process by the timer measurement is unnecessary, the switch circuit is turned off before the microcomputer shuts off the power supply (self-shutoff). Cut off the power supply to the timer circuit. By doing so, it is possible to suppress power consumption when the timer circuit is not used.

  In this embodiment, the switch circuit is turned off for a discharge time required for the timer IC power supply voltage to fall below the low voltage detection level, the switch circuit is turned on again, and communication is performed between the microcomputer and the timer IC. The microcomputer checks the low voltage detection flag. In this way, it is possible to determine whether the low voltage detection function is functioning normally, and it is possible to determine whether the timer IC can be used.

  Furthermore, when there is a problem in the communication state, such as when there is no response from the timer IC for communication from the microcomputer, the switch circuit is turned off from the microcomputer to cut off the power supply to the timer IC, and the switch circuit is turned on again. The timer IC is reset by turning on and supplying power to the timer IC. By doing in this way, it becomes possible to return to normal without the human act of removing the electronic control unit and the battery.

It is a figure which shows schematic structure of the electronic control apparatus by 1st Embodiment of this invention. It is a flowchart for demonstrating the whole process which the microcomputer in the electronic controller of 1st Embodiment performs. 3 is a flowchart for explaining details of a timer IC diagnosis process executed in the process of FIG. 2. It is a flowchart for demonstrating the detail of the IGSW check process performed in the process of FIG. It is a flowchart for demonstrating a timer IC reset process. It is a figure which shows schematic structure of the electronic control apparatus (modification) by 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery, 2 Ignition switch, 3 Load, 4 Power supply relay, 5 Load drive element, 6 Power supply IC, 7 Microcomputer, 8 Power supply switch circuit, 9 Self-feedback voltage, 10 Timer IC, 11 Drive circuit, 12 OR Circuit, 13 latch circuit, 100 electronic control device, 200 electronic control device

Claims (5)

A power supply means for outputting a main power supply voltage and a sub power supply voltage;
A microcomputer that operates by the main power supply voltage;
A timer circuit having a time counter operated by the sub power supply voltage;
A power supply switch for executing and shutting off the supply of the sub power supply voltage to the timer circuit,
The timer circuit measures an elapsed time by the time counter, and when the count value of the time counter reaches a predetermined value, sets a power activation signal for activating the microcomputer to an active level,
The power supply means outputs the main power supply voltage in response to the power activation signal,
The microcomputer detects a state in which the supply of the sub power supply voltage to the timer circuit is unnecessary, controls the power supply switch based on the detection result, and supplies the sub power supply voltage to the timer circuit. An electronic control device characterized by blocking.   2. The electronic control according to claim 1, further comprising state maintaining means for continuing the power supply switch to a connected state or a disconnected state even when the supply of the main power supply voltage to the microcomputer is interrupted. apparatus. The timer circuit has a low voltage detection function for detecting that the timer circuit is operating at a low voltage when the timer circuit is operating at a low voltage;
The microcomputer controls the power supply switch when the timer circuit is undiagnosed and forcibly cuts off the supply of the sub power supply voltage to the timer circuit. The electronic control device according to claim 1, wherein the electronic control device diagnoses whether the detection function operates normally.   The microcomputer has a function of monitoring a communication state with the timer circuit, and controls the power supply switch when there is a problem with the communication state with the timer circuit, and the sub power supply voltage to the timer circuit 4. The electronic control device according to claim 1, wherein the timer circuit is reset and returned to an initial state by reconnecting the power supply after being cut off for a certain period. 5.   5. The electronic control device according to claim 1, wherein the power supply unit is configured as a power supply IC, and the power supply switch is built in the power supply IC. 6.

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