Based on STM32F103, the first two levels of the TM03 capacitive displacement sensor are always high.

白小菜

Based on STM32F103, the first two levels of the TM03 capacitive displacement sensor are always high. [Copy link]

When I was learning to use STM32 to read the displacement value, I found that the first two levels were always 1 no matter how the data changed. I changed the PB11 SCK to rising edge trigger and only the first level was 1. According to the signal timing, it should be falling edge triggered.

I don't understand it. Please help me.

In the program, I use the PB11 SCK falling edge to trigger the interrupt, and then get the PB10 SDA level signal

uint8_t BinaryDisplacementData[20];		//接收位移的二进制数据
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
	if (GPIO_Pin == GPIO_PIN_11)
	{
    GPIO_PinState pin_state = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_10);
		if (pin_state == GPIO_PIN_SET) 
			pin_state = 1;
		else 
			pin_state = 0;
		i_data++;
    //获取0-19的20位数据
    if (i_data <= 19) {
			BinaryDisplacementData[i_data-1]= pin_state;
			
    }
    else if (i_data <= 23) {
        //获取20-23的四位标志位
      data21_24[i_21_24]=pin_state;
			i_21_24++;
    }
    else
    {
		for(uint8_t i=0;i<20;i++)
		{
			TM_N_data+=BinaryDisplacementData[i]<<i;
			printf(" %d",BinaryDisplacementData[i]);
		}
      	TM_N_data = 0x00;
		memset((uint8_t *)BinaryDisplacementData,0,20);
		memset(data21_24,0,4);
		i_data = 0x00;
		i_21_24=0x00;	
    }
  }
}

PB11 SDA IO configuration is falling edge trigger

  /*Configure GPIO pins : PBPin PBPin PB11 */
  GPIO_InitStruct.Pin = OK_Button_Pin|R_Button_Pin|GPIO_PIN_11;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  /*Configure GPIO pin : PB10 */
  GPIO_InitStruct.Pin = GPIO_PIN_10;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

The output shows that the first two are always 1, and the default should be 0.

Using an oscilloscope to check the signal, there is no problem. The upper one is SCK and the lower one is SDA

Jacktang

No matter how the data changes, it is always 1 when read.

There is a high probability that there is a problem with the hardware circuit