Optocoupler sensor module as RPM meter (Tachometer) with Blue Pill using STM32CubeIDE

Prerequisites

This project assumes you have already installed STM32CubeIDE. You need to have previously done a basic blink sketch with blue-pill using STM32CubeIDE. I have made a complete video from installing STM32CubeIDE to LED blink program. You can watch it by clicking this link. https://www.youtube.com/watch?v=kXg467nVd_A

Wiring Diagram

STM32CubeIDE Settings

Click RCC → High Speed Clock (HSE) to Crystal/Ceramic Resonator

Click Clock Configuration tab → HCLK (MHz) to 72

Click Pinout and Configuration tab

Click Timer → Click TIM2 →

Clock source to Internal Clock

Channel 1 set to Input Capture direct Mode

Configuration → NVIC Settings →

TIM2 global interrupt (tick)

Additional code on top of STM32CubeIDE generated code (in main.c)

/* USER CODE BEGIN 0 */
uint32_t counter = 0;
int speed = 0; // Tick per second
int rpm = 0; // Revolutions Per Minute
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
  counter++;
}
/* USER CODE END 0 */

/* USER CODE BEGIN 2 */
HAL_TIM_Encoder_Start_IT(&htim2, TIM_CHANNEL_1 );
/* USER CODE END 2 */

Additional code on top of STM32CubeIDE generated code (in stm32f1xx_it.c)

/* USER CODE BEGIN 0 */
extern uint32_t counter;
extern int speed;
extern int rpm;
int count = 0;
uint32_t oldcounter = 0;
/* USER CODE END 0 */

/* USER CODE BEGIN SysTick_IRQn 0 */
count++;
if (count == 1000)
{
  speed = counter - oldcounter; // Tick per second
  rpm = speed * 60 / 20; // Revolutions Per Minute
  oldcounter = counter;
  count = 0;
}
/* USER CODE END SysTick_IRQn 0 */