Vehicle mileage statistics method based on pulse counting

Abstract

A vehicle mileage statistics method based on pulse counting comprises the following steps: acquiring an output signal of a vehicle pulse sensor, and converting the signal of the vehicle pulse sensor into a digital signal which can be identified by an MCU (Microprogrammed Control Unit) through a hardware comparator circuit; the method comprises the following steps: acquiring a rising edge event of a vehicle pulse signal by adopting an input capture function of an MCU (Microprogrammed Control Unit), firstly reading a pulse count value of a backup domain register by the MCU, and then automatically adding 1 to the pulse count value of the backup domain register; and calculating a check value of the pulse count value, and writing the pulse count value and the check value back to the mileage backup domain register. According to the invention, the vehicle driving mileage counting can be updated and stored in real time, an additional memory is not needed, and the mileage counting is not lost when the equipment is restarted abnormally. And the vehicle driving mileage counting precision is high and reliable.

Description

technical field [0001] The invention relates to the field, in particular to a method and system for vehicle mileage statistics based on pulse counting. Background technique [0002] The national standard "GB / T19056-2012" requires that the vehicle driving recorder must record and store the vehicle mileage, and requires that the recording error within a certain mileage range is less than 0.1KM. Based on factors such as cost, the common practice is to allocate a RAM area inside the MCU for real-time recording of the mileage accumulation change. When the fixed distance (0.1KM) or timing (1S) conditions are met, the changed mileage value will be accumulated The total mileage is stored in NVM (Non-VolatileMemory, non-volatile memory) such as the internal flash of the MCU or external EEPROM. Whether internal flash or external EEPROM memory is used, frequent erasing and writing will have a great impact on the life of the memory, and even reach the limit value to cause damage. The l...

AI Technical Summary

Problems solved by technology

This method of mileage storage has a disadvantage. Most MCUs are affected by software quality and external factors. It is inevitable that they will encounter abnormal operation or restart due to watchdog timeout. If the NVM is being written before or is being written, the mileage data in the RAM cache of the MCU will no longer exist, which makes the accumulated mileage that has not been written into the NVM memory in time lost, resulting in an increase in the mileage statistics error

[0004] 2. Adding an external dedicated high-speed memory dedicated to storing mileage will increase the complexity of the hardware circuit and directly generate additional hardware costs

[0005] 3. Especially, for flash type NVM memory, before writing the mileage data to the flash, firstly erase the mileage address of the flash storage (usually erase by page), and then write the new mileage. In the event of a power outage after the flash is removed, the mileage will be permanently lost in this situation

[0006] 4. In particular, for flash-type NVM memory, the number of erasing and writing is shorter, and the design needs to consider the additional storage overhead and software development overhead caused by the equalized wear and tear of the flash memory.

The time to erase the flash plus the time to write to the flash is between 5ms and 10ms. Since the global interrupt is turned off during the operation of the flash, if a pulse edge signal arrives at this time, for the pulse count based on the capture interrupt function, it will not be generated. Input capture is interrupted, which also creates problems with increased mileage errors

6. When operating flash, the real-time performance of the MCU is reduced because the global interrupt is turned off.

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