Electronic control unit and data protection method therefor
An ECU includes a RAM; a non-volatile memory; and a controller for controlling reading of data from, and writing of data into, the RAM and non-volatile memory. The controller is configured to: store data generated during operation into the RAM, write the data into a storage area of the non-volatile memory when the operation stops, and read the data from the non-volatile memory into the RAM when the operation starts, and control a control target using the data. When determining that an improper reset is expected, the controller writes at least part of the data generated during the operation and stored in the RAM into a save area, different from the data storage area, of the non-volatile memory. When the operation restarts from the improper reset, the controller reads, into the RAM, the data that has been written in the storage and save areas.
1. An electronic control unit comprising:
a random access memory (RAM) utilizable as a work area;
a non-volatile memory for data storage; and
a controller for controlling reading of data from, and writing of data into, the RAM and the non-volatile memory, the controller being configured to:
store data generated during operation of the controller into the RAM,
write the data into a storage area of the non-volatile memory when the operation stops, and
read the data from the non-volatile memory into the RAM when the operation starts, and control a control target using the data,
in response to a determination that an improper reset of the controller is expected, write at least part of the data to be used in a subsequent driving cycle of a vehicle generated during the operation and stored in the RAM into a save area of the non-volatile memory, the save area being different from the storage area of the data,
when the operation restarts from the improper reset, read into the RAM, the data that has been written in the storage area and the data that has been written in the save area, the improper reset of the controller being a reset operation of the controller that occurs when the operation of the controller restarts after a power supply voltage of the controller has temporarily decreased to a level low enough to stop the operation of the controller while an ignition switch of the vehicle, which is the control target, is turned on, and
determine that the improper reset of the controller is expected either upon detecting that a current larger than a predetermined value is driven by control over the vehicle by the controller, and thus determining that a decrease of the power supply voltage of the controller is expected, or upon detecting a decrease of the power supply voltage.
2. The electronic control unit according to claim 1 , wherein the non-volatile memory previously stores therein a control program corresponding to the control target.
3. The electronic control unit according to claim 1 , wherein:
the controller is configured to acquire information relating to the vehicle from a sensor, and
the controller is configured to, based on the information from the sensor, calculate an operation variable for the control target, and control the control target using the operation variable.
4. The electronic control unit according to claim 3 , wherein the controller is initialized when the ignition switch of the vehicle gets turned on.
5. The electronic control unit according to claim 1 , wherein the data written into the save area of the non-volatile memory includes:
at least any one of fault information, a learned value, display data of a diagnostic tool, and information stored at the time of fault occurrence; and
a count value corresponding to latest data written into the storage area of the non-volatile memory.
6. The electronic control unit according to claim 1 , wherein when the controller determines that the improper reset of the controller is expected but the controller is not reset, the data that has been written in the save area of the non-volatile memory is erased.
7. A data protection method for an electronic control unit, comprising the steps of:
storing data generated during operation of a controller into a random access memory (RAM);
writing the data into a non-volatile memory when the operation stops;
reading the data from the non-volatile memory into the RAM when the operation starts, and controlling a control target using the data;
writing at least part of the data to be used in a subsequent driving cycle of a vehicle generated during the operation and stored in the RAM into a save area of the non-volatile memory, when it is determined that an improper reset of the controller is expected, the save area being different from a storage area of the data; and
reading, into the RAM, the data that has been written in the storage area and the data that has been written in the save area when the operation restarts from the improper reset, the improper reset of the controller being a reset operation of the controller that occurs when the operation of the controller restarts after a power supply voltage of the controller has temporarily decreased to a level low enough to stop the operation of the controller while an ignition switch of the vehicle, which is the control target, is turned on, and
wherein determining that the improper reset of the controller is expected occurs either upon detecting that a current larger than a predetermined value is driven by control over the vehicle by the controller, and thus determining that a decrease of the power supply voltage of the controller is expected, or upon detecting a decrease of the power supply voltage.
8. The data protection method for the electronic control unit according to claim 7 , further comprising the step of previously storing a control program corresponding to the control target into the non-volatile memory.
9. The data protection method for the electronic control unit according to claim 7 , further comprising the steps of:
causing the controller to acquire information relating to the vehicle from a sensor; and
causing the controller to calculate, based on the information from the sensor, an operation variable for the control target, and to control the control target using the operation variable.
10. The data protection method for the electronic control unit according to claim 9 , further comprising the step of initializing the controller when the ignition switch of the vehicle gets turned on.
11. The data protection method for the electronic control unit according to claim 7 , wherein the data written into the save area of the non-volatile memory includes:
at least any one of fault information, a learned value, display data of a diagnostic tool, and information stored at the time of fault occurrence; and
a count value corresponding to latest data written into the storage area of the non-volatile memory.
12. The data protection method for the electronic control unit according to claim 7 , further comprising the step of erasing the data that has been written in the save area of the non-volatile memory when it is determined that the improper reset of the controller is expected but the controller is not reset.