Control Servo by keypad 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

Set PA15, PB3, PB4 and PB5 to GPIO_Output

Set PB6 to GPIO_EXTI6

Set PB7 to GPIO_EXTI7

Set PB8 to GPIO_EXTI8

Set PB9 to GPIO_EXTI9

Click NVIC → EXTI line[9-5] interrupt → Enabled (Tick)

Click Timer → Click TIM2 →

Clock Source set to Internal Clock

Channel2 set to PWM Generation CH2

Configuration → Parameter Settings →

Prescaler set to 15

Counter Period 9999

Additional code on top of STM32CubeIDE generated code

/* USER CODE BEGIN PV */
GPIO_InitTypeDef GPIO_InitStructPrivate = {0};
uint32_t previousMillis = 0;
uint32_t currentMillis = 0;
uint8_t keyPressed = 0;
/* USER CODE END PV */

  /* USER CODE BEGIN 2 */
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 1);
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 1);
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 1);
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 1);
  HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_2);
  /* USER CODE END 2 */

/* USER CODE BEGIN 4 */
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
  currentMillis = HAL_GetTick();
  if (currentMillis - previousMillis > 10) {
    /*Configure GPIO pins : PB6 PB7 PB8 PB9 to GPIO_INPUT*/
    GPIO_InitStructPrivate.Pin = GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8|GPIO_PIN_9;
    GPIO_InitStructPrivate.Mode = GPIO_MODE_INPUT;
    GPIO_InitStructPrivate.Pull = GPIO_NOPULL;
    GPIO_InitStructPrivate.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStructPrivate);

    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 0);
    if(GPIO_Pin == GPIO_PIN_6 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_6))
    {
      keyPressed = 68; //ASCII value of D
    }
    else if(GPIO_Pin == GPIO_PIN_7 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_7))
    {
      keyPressed = 67; //ASCII value of C
    }
    else if(GPIO_Pin == GPIO_PIN_8 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_8))
    {
      keyPressed = 66; //ASCII value of B
    }
    else if(GPIO_Pin == GPIO_PIN_9 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_9))
    {
      keyPressed = 65; //ASCII value of A
    }

    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 0);
    if(GPIO_Pin == GPIO_PIN_6 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_6))
    {
      keyPressed = 35; //ASCII value of #
    }
    else if(GPIO_Pin == GPIO_PIN_7 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_7))
    {
      keyPressed = 57; //ASCII value of 9
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 1249);
    }
    else if(GPIO_Pin == GPIO_PIN_8 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_8))
    {
      keyPressed = 54; //ASCII value of 6
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 916);
    }
    else if(GPIO_Pin == GPIO_PIN_9 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_9))
    {
      keyPressed = 51; //ASCII value of 3
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 583);
    }

    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 0);
    if(GPIO_Pin == GPIO_PIN_6 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_6))
    {
      keyPressed = 48; //ASCII value of 0
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 250);
    }
    else if(GPIO_Pin == GPIO_PIN_7 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_7))
    {
      keyPressed = 56; //ASCII value of 8
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 1138);
    }
    else if(GPIO_Pin == GPIO_PIN_8 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_8))
    {
      keyPressed = 53; //ASCII value of 5
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 805);
    }
    else if(GPIO_Pin == GPIO_PIN_9 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_9))
    {
      keyPressed = 50; //ASCII value of 2
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 472);
    }

    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 0);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 1);
    if(GPIO_Pin == GPIO_PIN_6 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_6))
    {
      keyPressed = 42; //ASCII value of *
    }
    else if(GPIO_Pin == GPIO_PIN_7 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_7))
    {
      keyPressed = 55; //ASCII value of 7
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 1027);
    }
    else if(GPIO_Pin == GPIO_PIN_8 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_8))
    {
      keyPressed = 52; //ASCII value of 4
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 694);
    }
    else if(GPIO_Pin == GPIO_PIN_9 && HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_9))
    {
      keyPressed = 49; //ASCII value of 1
      __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2, 361);
    }

    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_15, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, 1);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, 1);
    /*Configure GPIO pins : PB6 PB7 PB8 PB9 back to EXTI*/
    GPIO_InitStructPrivate.Mode = GPIO_MODE_IT_RISING;
    GPIO_InitStructPrivate.Pull = GPIO_PULLDOWN;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStructPrivate);
    previousMillis = currentMillis;
  }
}
/* USER CODE END 4 */