HC-SR04 Ultrasonic Distance Sensor / OLED 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 TIM1 →

Clock Source set to Internal Clock

Configuration → Parameter Settings →

Prescaler set to 71

Click connectivity --> Click I2C1

For I2C select I2C

Configuration --> Parameter Settings

For I2C speed select Fast Mode

Set PA9 to GPIO_Output

Set PA8 to GPIO_Input

Libraries

Inside Core/Inc Folder

Inside Core/Src Folder

Additional code on top of STM32CubeIDE generated code

/* USER CODE BEGIN Includes */
#include "fonts.h"
#include "ssd1306.h"
#include "stdio.h"
/* USER CODE END Includes */

/* USER CODE BEGIN PV */
#define TRIG_PIN GPIO_PIN_9
#define TRIG_PORT GPIOA
#define ECHO_PIN GPIO_PIN_8
#define ECHO_PORT GPIOA
uint32_t pMillis;
uint32_t Value1 = 0;
uint32_t Value2 = 0;
uint16_t Distance  = 0;  // cm
char strCopy[15];
/* USER CODE END PV */

  /* USER CODE BEGIN 2 */
  HAL_TIM_Base_Start(&htim1);
  HAL_GPIO_WritePin(TRIG_PORT, TRIG_PIN, GPIO_PIN_RESET);  // pull the TRIG pin low
  SSD1306_Init();
  /* USER CODE END 2 */

  /* USER CODE BEGIN WHILE */
  while (1)
  {
    HAL_GPIO_WritePin(TRIG_PORT, TRIG_PIN, GPIO_PIN_SET);  // pull the TRIG pin HIGH
    __HAL_TIM_SET_COUNTER(&htim1, 0);
    while (__HAL_TIM_GET_COUNTER (&htim1) < 10);  // wait for 10 us
    HAL_GPIO_WritePin(TRIG_PORT, TRIG_PIN, GPIO_PIN_RESET);  // pull the TRIG pin low

    pMillis = HAL_GetTick(); // used this to avoid infinite while loop  (for timeout)
    // wait for the echo pin to go high
    while (!(HAL_GPIO_ReadPin (ECHO_PORT, ECHO_PIN)) && pMillis + 10 >  HAL_GetTick());
    Value1 = __HAL_TIM_GET_COUNTER (&htim1);

    pMillis = HAL_GetTick(); // used this to avoid infinite while loop (for timeout)
    // wait for the echo pin to go low
    while ((HAL_GPIO_ReadPin (ECHO_PORT, ECHO_PIN)) && pMillis + 50 > HAL_GetTick());
    Value2 = __HAL_TIM_GET_COUNTER (&htim1);

    Distance = (Value2-Value1)* 0.034/2;

    SSD1306_GotoXY (0, 0);
    SSD1306_Puts ("Distance:", &Font_11x18, 1);
    sprintf(strCopy,"%d    ", Distance);
    SSD1306_GotoXY (0, 30);
    SSD1306_Puts (strCopy, &Font_16x26, 1);
    SSD1306_UpdateScreen();
    HAL_Delay(50);
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */