JP6135539B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control device including a plurality of oscillation circuits.

  2. Description of the Related Art Conventionally, for example, each of a microcomputer and an integrated circuit includes an oscillation circuit, so that an electronic control unit (ECU) including a plurality of oscillation circuits is provided. The CR oscillation circuit using a capacitor and resistor as an oscillation circuit has the advantage of being able to be realized at a lower cost than the case of using a crystal oscillator, but the accuracy of the reference oscillation frequency is poor with respect to temperature and voltage fluctuations. There is a problem that. On the other hand, for example, Patent Document 1 discloses a technique for storing temperature characteristics and voltage characteristics of a reference oscillation frequency in a non-volatile memory at the time of manufacturing in a factory. According to Patent Document 1, it is possible to appropriately cope with a deviation in the reference oscillation frequency due to temperature and voltage fluctuations by referring to temperature characteristics and voltage characteristics stored in a nonvolatile memory at the time of use.

Japanese Patent Laid-Open No. 5-75445

  However, in Patent Document 1, it is necessary to store the temperature characteristics and voltage characteristics of the reference oscillation frequency in the nonvolatile memory at the time of manufacture at the factory, which causes a problem of increasing the number of processes and increasing the cost. Further, in the CR oscillation circuit, there is a possibility that the reference oscillation frequency shifts due to aging. However, Patent Document 1 does not consider the reference oscillation frequency shift due to aging. For this reason, when a deviation of the reference oscillation frequency due to aging occurs, even if the temperature characteristics and voltage characteristics stored in the non-volatile memory are referenced, the deviation of the reference oscillation frequency due to temperature and voltage fluctuations can be dealt with appropriately. There is a possibility that it cannot be done.

  The present invention has been made in view of the above-described circumstances, and its purpose is when a shift in the reference oscillation frequency due to secular change occurs without causing an increase in process and cost in manufacturing at a factory. However, an object of the present invention is to provide an electronic control device that can appropriately cope with temperature and voltage fluctuations.

According to the first aspect of the present invention, the first measuring unit measures the number of clocks of the first clock signal output from the first oscillation circuit. The second measuring means measures the number of clocks of the second clock signal output from the second oscillation circuit. The measurement control means starts the measurement of the number of clocks of each of the first clock signal and the second clock signal at the same time, and ends them simultaneously after a predetermined measurement period has elapsed. The difference calculating means calculates an index indicating the difference in the number of clocks at the time when the measurement of the number of clocks is simultaneously completed. The storage control means includes the calculated index and at least one physical quantity of the temperature of the second oscillation circuit and the voltage applied to the second oscillation circuit when the measurement of the number of clocks is simultaneously completed. The correspondence is stored in the storage means. The storage control means stores the correspondence between the index and the physical quantity in the storage means when the fluctuation range of the physical quantity in the measurement period is less than the predetermined value, and the fluctuation quantity of the physical quantity in the measurement period is equal to or greater than the predetermined value. In some cases, storage of the correspondence between the index and the physical quantity in the storage unit is prohibited.

  In the first oscillation circuit, the deviation of the reference oscillation frequency due to secular change does not occur, but when the deviation of the reference oscillation frequency due to secular change occurs in the second oscillation circuit, the difference in the number of clocks within a predetermined measurement period. Will occur. In this case, an index indicating the difference in the number of clocks is calculated, and by using the calculated index, the number of clocks output from the second oscillation circuit is matched with the number of clocks output from the first oscillation circuit. Can be corrected. Further, by storing the calculated index in association with the temperature and voltage at the time when the measurement of the number of clocks is simultaneously completed, the number of clocks can be corrected in consideration of temperature and voltage fluctuations. . As a result, in a configuration including a plurality of oscillation circuits, even when a deviation of the reference oscillation frequency due to aging occurs in any of the oscillation circuits, it is possible to appropriately cope with temperature and voltage fluctuations. At this time, it is not necessary to memorize the temperature characteristic and voltage characteristic of the reference oscillation frequency at the time of manufacture in the factory, and there is no increase in the process and cost.

Functional block diagram showing an embodiment of the present invention flowchart Diagram showing fluctuations in substrate temperature and voltage (1) The figure which shows a learning value table (the 1) Diagram showing fluctuations in substrate temperature and voltage (Part 2) The figure which shows a learning value table (the 2) The figure which shows a learning value table (the 3) The figure which shows a learning value table (the 4)

  Hereinafter, an embodiment in which the present invention is applied to an electronic control unit (ECU) that can be mounted on a vehicle will be described with reference to the drawings. The electronic control device 1 is, for example, an engine ECU that controls the driving of an engine that is a driving source of a vehicle, and is a device that is used in an environment where the ambient temperature varies greatly. The electronic control device 1 includes a microcomputer 2, a timer IC (Integrated Circuit) 3 (integrated circuit), a crystal oscillator 4, a temperature sensor 5, and an AD conversion unit 6.

  The microcomputer 2 has a high-precision oscillation circuit 7 (first oscillation circuit). The microcomputer 2 also includes a measurement control unit 8 (measurement control unit), a measurement unit 9 (first measurement unit), a difference ratio calculation unit 10 (difference calculation unit), and temperature detection according to functions to be executed. A unit 11 (temperature detection unit), a voltage detection unit 12 (voltage detection unit), a storage control unit 13 (storage control unit), and a correction unit 14 (correction unit). The microcomputer 2 realizes these units 8 to 14 by software. Further, the microcomputer 2 has a nonvolatile memory 15 (storage means). The timer IC 3 has a low-precision oscillation circuit 16 (second oscillation circuit). The timer IC 3 realizes the measuring unit 17 (second measuring means) by software.

  When a voltage is applied to the crystal of the quartz crystal that is a piezoelectric body (when an electric field is applied), the piezoelectric body is deformed and outputs an oscillation signal (oscillates). In the microcomputer 2, when the oscillation signal is input from the crystal oscillator 4, the high-precision oscillation circuit 7 generates a clock signal (first clock signal) from the input oscillation signal and supplies the clock signal to the measurement control unit 8 and the measurement unit 9. Output. The microcomputer 2 operates using the clock signal output from the high precision oscillation circuit 7 as an operation clock. The high-accuracy oscillation circuit 7 has the property that the deviation of the reference oscillation frequency due to secular change is extremely small because the accuracy of the oscillation frequency of the crystal oscillator 4 is high.

  The measurement control unit 8 outputs a start command simultaneously to the measurement unit 9, the temperature detection unit 11, the voltage detection unit 12, and the measurement unit 17 of the timer IC 3 at the start timing of a timer difference ratio calculation process described later. Further, the measurement control unit 8 outputs a start command, and at the same time, starts measuring the number of clocks (number of pulses) of the clock signal input from the high precision oscillation circuit 7. When the number of clocks being measured reaches a predetermined reference value, the measurement control unit 8 sends an end command to the measurement unit 9, the temperature detection unit 11, the voltage detection unit 12, and the measurement unit 17 of the timer IC 3 simultaneously. Output and finish measuring the number of clocks. The reference value may be a fixed value set at the time of manufacture in a factory, or may be a variable value that can be changed by a mechanic or the like in consideration of, for example, the use environment.

  When the measurement unit 9 receives a start command from the measurement control unit 8, the measurement unit 9 starts measuring the number of clocks (number of pulses) of the clock signal input from the high-precision oscillation circuit 7. Then, when the measurement unit 9 inputs an end command from the measurement control unit 8 during the measurement of the number of clocks, the measurement unit 9 ends the measurement of the number of clocks and sets a value corresponding to the measured number of clocks (the number of clocks within the measurement period). It outputs to the difference ratio calculation part 10 as a timer value in a microcomputer.

  In the timer IC 3, the low-accuracy oscillation circuit 16 includes a CR oscillation circuit, generates a clock signal (second clock signal) from the oscillation signal oscillated by the CR oscillation circuit, and outputs the clock signal to the measurement unit 17. The timer IC 3 operates using the clock signal output from the low precision oscillation circuit 16 as an operation clock. The CR oscillation circuit constituting the low-accuracy oscillation circuit 16 has poor accuracy of the reference oscillation frequency with respect to temperature and voltage fluctuations, and the deviation of the reference oscillation frequency due to secular change is higher than that of the high-precision oscillation circuit 7 described above. Also has great properties.

  When the measurement unit 17 receives a start command from the measurement control unit 8, the measurement unit 17 starts measuring the number of clocks (number of pulses) of the clock signal input from the low-precision oscillation circuit 16. When the measurement unit 17 inputs an end command from the measurement control unit 8 during the measurement of the number of clocks, the measurement unit 17 ends the measurement of the number of clocks and sets a value corresponding to the measured number of clocks (the number of clocks within the measurement period). The value is output to the difference ratio calculation unit 10 and the correction unit 14 as a timer value in the timer IC.

  The temperature sensor 5 detects the temperature of the substrate on which the timer IC 3 is mounted (substrate temperature) as the temperature of the low-accuracy oscillation circuit 16 and outputs the detected substrate temperature to the temperature detection unit 11. When the temperature detection unit 11 receives a start command from the measurement control unit 8, the temperature detection unit 11 starts monitoring the substrate temperature input from the temperature sensor 5. When the temperature detection unit 11 starts monitoring the substrate temperature, the temperature detection unit 11 updates the maximum value of the substrate temperature every time the substrate temperature exceeds the maximum value after starting the monitoring, and sets the minimum value of the substrate temperature every time the temperature falls below the minimum value. Update. When the temperature detection unit 11 inputs an end command from the measurement control unit 8 while monitoring the substrate temperature, the temperature detection unit 11 ends the monitoring of the substrate temperature input from the temperature sensor 5. Then, the temperature detection unit 11 calculates the absolute value of the difference between the maximum value and the minimum value of the substrate temperature within the measurement period from the input of the start command to the input of the end command, and the calculated difference The absolute value is compared with a predetermined value defined in advance. The predetermined value that is a criterion for determining the substrate temperature may be a fixed value that is set at the time of manufacture in the factory, as in the case of the above-described reference value. It may be a variable value. If the absolute value of the calculated difference is less than the predetermined value, the temperature detection unit 11 outputs the substrate temperature at the time when the monitoring is finished to the storage control unit 13. On the other hand, if the absolute value of the calculated difference is equal to or greater than a predetermined value, the temperature detection unit 11 does not output the substrate temperature at the time of termination of monitoring to the storage control unit 13 (prohibits output).

  The AD conversion unit 6 detects the voltage applied to the timer IC 3 (the power supply voltage of the timer IC 3 and is normally 5 [V], for example), and outputs the detected voltage to the voltage detection unit 12. When the voltage detection unit 12 receives a start command from the measurement control unit 8, the voltage detection unit 12 starts monitoring the voltage input from the AD conversion unit 6. When voltage monitoring starts, the voltage detection unit 12 updates the maximum value of the voltage every time the voltage exceeds the maximum value after starting monitoring, and updates the minimum value of the voltage every time the voltage falls below the minimum value. When the voltage detection unit 12 inputs an end command from the measurement control unit 8 during voltage monitoring, the voltage detection unit 12 ends monitoring of the voltage input from the AD conversion unit 6. The voltage detector 12 calculates the absolute value of the difference between the maximum value and the minimum value of the voltage within the measurement period from the input of the start command to the input of the end command, and the absolute value of the calculated difference The value is compared with a predetermined value defined in advance. Similarly to the above-described reference value, the predetermined value serving as the voltage determination reference may be a fixed value set at the time of manufacturing in the factory, or a variable that can be changed by a mechanic considering the use environment, for example. It may be a value. If the absolute value of the calculated difference is less than the predetermined value, the voltage detection unit 12 outputs the voltage at the time when the monitoring is finished to the storage control unit 13. On the other hand, if the absolute value of the calculated difference is equal to or greater than a predetermined value, the voltage detection unit 12 does not output the voltage at the time when the monitoring is terminated to the storage control unit 13 (prohibits output).

The storage control unit 13 outputs a calculation command to the difference ratio calculation unit 10 on condition that the substrate temperature is input from the temperature detection unit 11 and the voltage is input from the voltage detection unit 12.
When the calculation command is input from the storage control unit 13, the difference ratio calculation unit 10 uses the timer value in the microcomputer input from the measurement unit 9 and the timer value in the timer IC input from the measurement unit 17. The timer difference ratio is calculated according to the following calculation formula.
Timer difference ratio = timer value in the microcomputer / timer value in the timer IC Then, the difference ratio calculation unit 10 outputs the calculated timer difference ratio to the storage control unit 13.

  The nonvolatile memory 15 holds a learning value table capable of storing a timer difference ratio with the substrate temperature and voltage as axes (variables). When the storage controller 13 receives the timer difference ratio from the difference ratio calculator 10, the storage controller 13 receives the input timer difference ratio from the temperature detector 11 and the voltage input from the voltage detector 12. Are stored in the learning value table of the nonvolatile memory 15 in association with. Further, the storage control unit 13 reads the timer difference ratio stored in the learning value table of the nonvolatile memory 15 and outputs the read timer difference ratio to the correction unit 14.

When the correction unit 14 inputs the timer value in the timer IC from the measurement unit 17 and inputs the timer difference ratio from the storage control unit 13, the correction unit 14 converts the timer value in the timer IC input from the measurement unit 17 from the storage control unit 13. Correction is made using the input timer difference ratio. That is, the correction unit 14 calculates the timer value in the timer IC after correction according to the following arithmetic expression.
Timer value in timer IC after correction = Timer value in timer IC before correction × Timer difference ratio The electronic control device 1 configured in this way is activated in conjunction with, for example, an ACC (accessory) switch of a vehicle. And switching between the stopped state. That is, when the electronic control unit 1 determines that the ACC switch is switched from OFF to ON, the electronic control unit 1 switches from the stopped state to the activated state. Change.

Next, the operation of the above configuration will be described with reference to FIGS.
In the activated state of the electronic control unit 1, the microcomputer 2 executes the timer difference ratio calculation process when a request for execution of the timer difference ratio calculation process related to the present invention occurs. In this case, the microcomputer 2 may generate an execution request periodically at a predetermined cycle, for example, or may generate an execution request in response to an instruction from the timer IC 3.

  When the microcomputer 2 starts the timer difference ratio calculation process, the microcomputer 2 outputs a start command from the measurement control unit 8 to the measurement unit 9, the temperature detection unit 11, the voltage detection unit 12, and the measurement unit 17 of the timer IC 3 simultaneously. The microcomputer 2 starts measuring the clock signal output from its own high-precision oscillation circuit 7 by the measurement unit 9 and measures the clock signal output from the low-precision oscillation circuit 16 of the timer IC 3. (S1). At this time, the microcomputer 2 starts monitoring the substrate temperature input from the temperature sensor 5 at the temperature detection unit 11 and starts monitoring the voltage input from the AD conversion unit 6 at the voltage detection unit 12. . Thereafter, the microcomputer 2 updates the maximum value of the substrate temperature every time the substrate temperature exceeds the maximum value, and updates the minimum value of the substrate temperature every time it falls below the minimum value. The microcomputer 2 updates the maximum voltage every time the voltage exceeds the maximum value, and updates the minimum voltage every time the voltage falls below the minimum value (S2). The microcomputer 2 repeatedly updates the substrate temperature and voltage until it is determined by the measurement control unit 8 that the number of clocks being measured has reached the reference value (S3: NO).

  Next, when the microcomputer 2 determines that the number of clocks being measured by the measurement control unit 8 has reached the reference value (a predetermined measurement period has elapsed) (S3: YES), the microcomputer 2 measures an end command from the measurement control unit 8. Output simultaneously to the unit 9, the temperature detection unit 11, the voltage detection unit 12, and the measurement unit 17 of the timer IC 3. The microcomputer 2 ends the measurement of the clock signal output from its own high-precision oscillation circuit 7 and ends the measurement of the clock signal output from the low-precision oscillation circuit 16 of the timer IC 3 (S4).

  Next, the microcomputer 2 calculates the absolute value of the difference between the maximum value and the minimum value of the substrate temperature within the measurement period by the temperature detection unit 11, and calculates the absolute value of the calculated difference and the predetermined value as the temperature detection unit. 11 is compared (S5). When the microcomputer 2 determines that the absolute value of the calculated difference is less than the predetermined value (S5: YES), the substrate temperature at the time when the monitoring is finished is set as the current substrate temperature from the temperature detection unit 11 to the storage control unit 13. Output.

  Next, the microcomputer 2 calculates the absolute value of the difference between the maximum value and the minimum value of the voltage within the measurement period by the voltage detection unit 12, and calculates the absolute value of the calculated difference and the predetermined value as the voltage detection unit 12. (S6). When the microcomputer 2 determines that the absolute value of the calculated difference is less than the predetermined value (S6: YES), the voltage at the time when the monitoring is finished is output from the voltage detection unit 12 to the storage control unit 13 as the current voltage. .

  Next, the microcomputer 2 outputs a calculation command from the storage control unit 13 to the difference ratio calculation unit 10, the timer value in the microcomputer input from the measurement unit 9, and the timer IC input from the measurement unit 17. The timer difference ratio is calculated by the difference ratio calculation unit 10 using the timer value (S7). Next, the microcomputer 2 searches for the current substrate temperature in the learned value table (S8), and searches for the current voltage in the learned value table (S9). Then, the microcomputer 2 stores the timer difference ratio calculated by the difference ratio calculation unit 10 in the learning value table of the nonvolatile memory 15 in association with the current substrate temperature and the current voltage (S10), and the timer difference ratio. The computation process ends. If the microcomputer 2 determines that the absolute value of the difference between the maximum value and the minimum value of the substrate temperature within the measurement period is not less than the predetermined value (is greater than or equal to the predetermined value) (S5: NO), the timer difference ratio is set. The timer difference ratio calculation process is terminated without calculation by the difference ratio calculation unit 10. If the microcomputer 2 determines that the absolute value of the difference between the maximum value and the minimum value of the voltage within the measurement period is not less than the predetermined value (is greater than or equal to the predetermined value) (S6: NO), in this case also the timer The timer difference ratio calculation process is terminated without calculating the difference ratio by the difference ratio calculation unit 10.

  Thereafter, when using the clock signal output from the low-accuracy oscillation circuit 16, the microcomputer 2 reads the timer difference ratio stored in the nonvolatile memory 15 corresponding to the substrate temperature and voltage at that time. put out. Then, the microcomputer 2 corrects the timer value in the timer IC input from the measurement unit 17 by the correction unit 14 using the timer difference ratio read from the nonvolatile memory 15.

The microcomputer 2 performs the above-described timer difference ratio calculation process to store (update) the timer difference ratio as follows. As shown in FIG. 3, the microcomputer 2 sets the measurement period to “600 s”, for example, and the fluctuation range (| T _max −T _min |) of the substrate temperature within the measurement period is less than a predetermined value (A), When the voltage fluctuation range (| V _max −V _min |) is less than the predetermined value (B), the timer value in the microcomputer is measured as “600 s”, and the timer value in the timer IC is set to “630 s”. When measured, the timer difference ratio is calculated according to the following calculation formula.
Timer difference ratio = 600 s / 630 s≈0.95

  For example, if the microcomputer 2 specifies the current substrate temperature as “30 ° C.” and specifies the current voltage as “5 V”, the calculated timer difference ratio “0.95” is set to the current substrate temperature. It is stored in the learning value table of the nonvolatile memory 15 in association with a certain “30 ° C.” and the current voltage “5 V”. That is, as shown in FIG. 4, the microcomputer 2 sets the timer difference ratio “0.96” when the substrate temperature up to that time is “30 ° C.” and the voltage is “5 V” to the timer calculated by this calculation. The difference ratio is updated to “0.95”. The microcomputer 2 may store the timer difference ratio as a fraction without calculating it to the second decimal place, or may store “600 s / 630 s”. That is, the microcomputer 2 stores the fractional ratio of the timer difference ratio without calculating it to the second decimal place, thereby suppressing an error in correcting the timer value in the timer IC (avoiding a decrease in accuracy). ).

The correction unit 14 corrects the timer value in the timer IC before correction input from the measurement unit 17 by using the timer difference ratio calculated this time. That is, the correction unit 14 multiplies “630 s”, which is the timer value in the timer IC before correction input from the measurement unit 17, by “600 s / 630 s”, which is the timer difference ratio calculated this time. The timer value in the timer IC is calculated according to the following equation.
Timer value in the timer IC after correction = 630 s × (600 s / 630 s) = 600 s

  On the other hand, as shown in FIG. 5, the microcomputer 2 calculates a timer difference ratio when the fluctuation range of the voltage within the measurement period is less than the predetermined value but the fluctuation range of the substrate temperature is equal to or larger than the predetermined value. There is no. That is, as shown in FIG. 6, the microcomputer 2 continues without updating the timer difference ratio “0.96” when the substrate temperature up to that point is “30 ° C.” and the voltage is “5 V”. . The microcomputer 2 does not calculate the timer difference ratio when the fluctuation range of the substrate temperature within the measurement period is less than the predetermined value, but the same is true when the fluctuation range of the voltage is greater than or equal to the predetermined value. Further, the microcomputer 2 does not calculate the timer difference ratio when both the fluctuation range of the substrate temperature and the fluctuation range of the voltage within the measurement period are equal to or greater than the respective predetermined values.

  In the above, the configuration in which the learning value table having both the substrate temperature and the voltage as the axes is held in the nonvolatile memory 15 is described. However, the learning value table having either the substrate temperature or the voltage as the axes is held. May be. That is, in an environment where the substrate temperature varies greatly but the voltage variation is small (for example, stable at 5 [V]), as shown in FIG. May be held. Also, in an environment where the fluctuation of the voltage is large but the fluctuation of the substrate temperature is small (eg, stable at 30 [° C.]), a learning value table with only the voltage as an axis is held as shown in FIG. You may do it. That is, the learning value table axis may be determined according to the environment in which the electronic control unit 1 is used. The numerical values shown in FIGS. 3 to 8 are examples.

  As described above, according to the present embodiment, in the electronic control unit 1, measurement of the number of clocks output from the high-precision oscillation circuit 7 and measurement of the number of clocks output from the low-precision oscillation circuit 16 are started simultaneously. Then, it ends simultaneously after a predetermined measurement period. Then, the difference ratio indicating the difference in the number of clocks within the measurement period is calculated, and the calculated difference is stored in the learning value table in association with the substrate temperature and voltage at the time when the measurement of the clock number is simultaneously completed. I tried to do it. Thereby, even when the deviation of the reference oscillation frequency due to aging occurs in the low-accuracy oscillation circuit 16, it is possible to appropriately cope with fluctuations in the substrate temperature and voltage. At this time, it is not necessary to memorize the temperature characteristic and voltage characteristic of the reference oscillation frequency at the time of manufacture in the factory, and there is no increase in the process and cost.

  In addition, the timer value in the timer IC before correction is corrected using the timer difference ratio. Thereby, the influence of the deviation of the reference oscillation frequency due to the secular change can be quickly eliminated.

  Further, when the fluctuation range of the substrate temperature within the measurement period is less than the predetermined value and the fluctuation range of the voltage is less than the predetermined value, the timer difference ratio is calculated and stored, and the fluctuation range of the substrate temperature is predetermined. The timer difference ratio is not calculated when the value is equal to or greater than the value or the voltage fluctuation range is equal to or greater than the predetermined value. As a result, since the possibility of mislearning is high when the fluctuation range is greater than or equal to a predetermined value, it is possible to avoid storing a timer difference ratio with a high possibility of mislearning in advance and improve reliability. Can do.

The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.
Not only using a crystal oscillator, but also a ceramic oscillator in which the deviation of the reference oscillation frequency due to secular change is approximately the same as that of the crystal oscillator may be used.
As an index indicating the difference in the number of clocks, the timer value in the microcomputer is subtracted from the timer value in the timer IC as well as calculating the value (ratio) obtained by dividing the timer value in the microcomputer by the timer value in the timer IC. The calculated value (difference) may be calculated. In that case, calculate the timer difference according to the following formula,
Timer difference = timer value in timer IC−timer value in microcomputer The timer value in the timer IC after correction may be calculated according to the following equation.

Timer value in timer IC after correction = timer value in timer IC before correction−timer difference One is not limited to controlling the start and end of clock number measurement by distinguishing start and end instructions. The start and end of measurement of the number of clocks may be controlled by an instruction. That is, the measurement of a predetermined measurement period may be continuously performed by ending the measurement of the number of clocks with one command and starting (restarting) the next measurement.

  After calculating the timer difference ratio, compare the substrate temperature fluctuation width and voltage fluctuation width within the measurement period with their respective predetermined values, and if the conditions are met, the calculated timer difference ratio is The temperature may be stored in association with the current voltage. In other words, the timer difference ratio may be calculated after comparing the fluctuation range of the substrate temperature and the fluctuation range of the voltage with the respective predetermined values, or after calculating the timer difference ratio, the fluctuation range of the substrate temperature and the fluctuation range of the voltage are calculated. You may compare with each predetermined value.

  In the drawings, 1 is an electronic control device, 2 is a microcomputer, 3 is a timer IC (integrated circuit), 7 is a high-precision oscillation circuit (first oscillation circuit), 8 is a measurement control unit (measurement control means), 9 is Measurement unit (first measurement unit), 10 is a difference ratio calculation unit (difference calculation unit), 11 is a temperature detection unit (temperature detection unit), 12 is a voltage detection unit (voltage detection unit), and 13 is a storage control unit ( (Storage control means), 14 is a correction unit (correction means), 15 is a non-volatile memory (storage means), 16 is a low-precision oscillation circuit (second oscillation circuit), and 17 is a measurement unit (second measurement means). is there.

Claims (4)

A first oscillation circuit (7) for outputting a first clock signal;
A second oscillation circuit (16) for outputting a second clock signal;
First measuring means (9) for measuring the number of clocks of the first clock signal;
Second measuring means (17) for measuring the number of clocks of the second clock signal;
Measurement control means (8) for simultaneously starting measurement of the number of clocks of each of the first clock signal and the second clock signal and ending simultaneously after a predetermined measurement period has elapsed;
Difference calculating means (10) for calculating an index indicating a difference in the number of clocks at the time when the measurement of the number of clocks is simultaneously terminated;
At least one of temperature detection means (11) for detecting the temperature of the second oscillation circuit and voltage detection means (12) for detecting a voltage applied to the second oscillation circuit;
Storage control for storing in the storage means (15) the correspondence between the index and the physical quantity detected by at least one of the temperature detection means and the voltage detection means when the measurement of the number of clocks is simultaneously completed Means (13) ,
The storage control unit causes the storage unit to store a correspondence between the index and the physical quantity when the fluctuation range of the physical quantity within the measurement period is less than a predetermined value, and the physical quantity within the measurement period. An electronic control device that prohibits the storage of the correspondence between the index and the physical quantity in the storage means when the fluctuation range of the is not less than a predetermined value. The electronic control device according to claim 1,
Correction means (14) for correcting the number of clocks of the second clock signal measured by the second measurement means based on the correspondence between the index and the physical quantity stored in the storage means; An electronic control device characterized by that. In the electronic control device according to claim 1 or 2,
Having both the temperature detection means and the voltage detection means;
The storage control means stores the correspondence between the index and the temperature detected by the temperature detection means and the voltage detected by the voltage detection means when the measurement of the number of clocks is simultaneously completed. An electronic control device characterized in that it is stored in a means. In the electronic control device according to any one of claims 1 to 3,
The first oscillation circuit is provided in a microcomputer (2) that operates using the first clock signal as an operation clock,
The electronic control device according to claim 2, wherein the second oscillation circuit is provided in an integrated circuit (3) that operates using the second clock signal as an operation clock .

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