Software configuration problem of using the "external counting" TIMx_ETR pulse measurement of the stm8 microcontroller

During my internship in my senior year, I needed to use an STM8 microcontroller to measure the frequency of a square wave pulse. At first, I wanted to use a timer to capture the pulse, but the pulse frequency I needed to measure was high, and the capture measurement was not only inaccurate, but also inefficient. So I thought of using the external counting TIMx_ETR function to measure!

The real problem is that I have never used the external pulse counting function of STM8 before, and I can't find how to configure the external pulse counting mode on the Internet. The company's progress is still moving forward. What's more annoying is that most of the data manuals of STM8 are in English, unlike the STM32 microcontrollers, which have many Chinese versions. This made me very anxious. But I still worked overtime overnight to read the English documents.

After 2 days of hard work, I finally found a solution. I was so excited that I couldn't express it in words. Without further ado, I would like to share with you the configuration tips of TIMx_ETR of STM8 microcontroller:

1: In fact, the configuration method of the TIMx_ETR function of the STM8 microcontroller is different for the STM8S series and the STM8L series; STM8S is the standard version, while STM8L is the low-power version;

For the external counting configuration of the STM8S series, it is necessary to modify the option bytes in the FLASH to activate the remapping function of TIMx_ETR. By looking at the "option bytes" section of the manual, you can find that there is an option byte called OPT2 in the remapping option of the 4803h address of the STM8S. When 0X20 is written to the OPT2 byte, the PB3 pin can be mapped to the TIMx_ETR external pulse counting function pin. After configuring the option bytes, there is another issue worth noting: at this time, the pin of the PB3 pin must be configured as "pull-up input and no external interrupt", that is, the sentence GPIO_Init(GPIOB, GPIO_Pin_3, GPIO_Mode_In_PU_No_IT); in the library function. The attached program is as follows:

{

TIM1_DeInit();

CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER1, ENABLE); // Enable the clock of timer 2.

FLASH_Unlock(FLASH_MEMTYPE_DATA); //解锁

while(FLASH_GetFlagStatus(FLASH_FLAG_DUL) == RESET);

FLASH_ProgramOptionByte(0x4803,0x20); //option byte, write 0X20 to address 0X4803

u8 status;

status=FLASH_WaitForLastOperation(FLASH_MEMTYPE_DATA);

if(status==FLASH_STATUS_SUCCESSFUL_OPERATION)

{}

FLASH_Lock(FLASH_MEMTYPE_DATA);

TIM1_ETRClockMode2Config(TIM1_EXTTRGPSC_DIV2, 

TIM1_EXTTRGPOLARITY_INVERTED,0x00); //External counting configuration

TIM1_TimeBaseInit(1,TIM1_COUNTERMODE_UP,9999,0);

TIM1_ITConfig(TIM1_IT_UPDATE,ENABLE);

TIM1_SetCounter(0x0);

TIM1_ClearITPendingBit(TIM1_IT_UPDATE); //Reference library

TIM1_Cmd(ENABLE);

}

2: However, not all STM8 microcontrollers need to change the option bytes. For STM8L series microcontrollers, there is no need to modify the option bytes. You can directly configure them. The program code is as follows:

TIM2_DeInit();

CLK_PeripheralClockConfig(CLK_Peripheral_TIM2, ENABLE); // Enable the clock of timer 2

TIM2_ETRClockMode2Config(TIM2_ExtTRGPSC_DIV2, 

TIM2_ExtTRGPolarity_Inverted,0x00);

TIM2_TimeBaseInit(TIM2_Prescaler_1,TIM2_CounterMode_Up,9999);//Do you need to add?

TIM2_ITConfig(TIM2_IT_Update,ENABLE);

TIM2_SetCounter(0x0);

TIM2_ClearITPendingBit(TIM2_IT_Update); //Reference library

TIM2_Cmd(ENABLE);

Hope it helps!