STM32G0B1KBU3N I2C comms, can't see wave form

grisom13 · ‎2025-09-29

Hello again :)

I have used all ideas including chat GPT. I can't see any changes in I2C line with oscilloscope. STM32G0B1KBU3N have Pin PB9 as SDA and PA9 as SLC. 3.3Volts pull up via 4.7 kOhm resistor. I am trying negotiate with LM51772 DC-DC buck-boost converter. No external clock crystal. I am sure the issue in the code but because lack op experience cant see where. Please support with the solution. Below is the code and the debug message. I am in desperate. Thank you.

set *(int *)0xE000EDFC=*(int *)0xE000EDFC|0x400 Temporary breakpoint 1, main () at ../Core/Src/main.c:82 82 HAL_Init();

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#define LM51772_ADDR         (0x6A << 1)  // 8-bit I2C address
#define IVP_VOLTAGE_REG      0xDA         // Output voltage register
#define CONTROL_REG1         0x01         // Example: control/config register
#define VOLTAGE_20V_VALUE    0x7A         // From datasheet table
#define ENABLE_IVP           0x01         // Bit to enable I2C voltage programming
/* USER CODE END Includes */

/* Private variables ---------------------------------------------------------*/
I2C_HandleTypeDef hi2c1;

/* USER CODE BEGIN PV */
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C1_Init(void);
static void MX_UCPD1_Init(void);

/* USER CODE BEGIN 0 */
void LM51772_SetOutput20V(void)
{
    uint8_t buf[2];

    // Step 1: Enable I2C programmable voltage (IVP)
    buf[0] = CONTROL_REG1;    // Control register address
    buf[1] = ENABLE_IVP;      // Set IVP enable bit
    if (HAL_I2C_Master_Transmit(&hi2c1, LM51772_ADDR, buf, 2, HAL_MAX_DELAY) != HAL_OK)
    {
        Error_Handler();
    }

    HAL_Delay(1); // small delay to let settings apply

    // Step 2: Set target voltage (20V)
    buf[0] = IVP_VOLTAGE_REG; // Voltage register
    buf[1] = VOLTAGE_20V_VALUE;
    if (HAL_I2C_Master_Transmit(&hi2c1, LM51772_ADDR, buf, 2, HAL_MAX_DELAY) != HAL_OK)
    {
        Error_Handler();
    }

    HAL_Delay(1); // allow the chip to update output
}
/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
    /* USER CODE BEGIN 1 */
    /* USER CODE END 1 */

    /* MCU Configuration--------------------------------------------------------*/

    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
    HAL_Init();

    /* Configure the system clock */
    SystemClock_Config();

    /* Initialize all configured peripherals */
    MX_GPIO_Init();
    MX_I2C1_Init();
    MX_UCPD1_Init();

    /* USER CODE BEGIN 2 */
    // Set initial LED states
    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_7, GPIO_PIN_SET);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_0, GPIO_PIN_SET);
    HAL_GPIO_WritePin(GPIOB, GPIO_PIN_1, GPIO_PIN_SET);

    // Configure LM51772 output voltage
    LM51772_SetOutput20V();
    /* USER CODE END 2 */

    /* Infinite loop */
    /* USER CODE BEGIN WHILE */
    while (1)
    {
        // Toggle LEDs
        HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_7);
        HAL_Delay(500);
        HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_0);
        HAL_Delay(500);
        HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_1);
        HAL_Delay(500);
        /* USER CODE END WHILE */

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

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

    HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);

    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
        Error_Handler();
    }

    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                                |RCC_CLOCKTYPE_PCLK1;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
    {
        Error_Handler();
    }
}

/**
  * @brief I2C1 Initialization Function
  * @retval None
  */
static void MX_I2C1_Init(void)
{
    hi2c1.Instance = I2C1;
    hi2c1.Init.Timing = 0x10301313;
    hi2c1.Init.OwnAddress1 = 0;
    hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
    hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
    hi2c1.Init.OwnAddress2 = 0;
    hi2c1.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
    hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
    hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
    if (HAL_I2C_Init(&hi2c1) != HAL_OK)
    {
        Error_Handler();
    }

    if (HAL_I2CEx_ConfigAnalogFilter(&hi2c1, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
    {
        Error_Handler();
    }

    if (HAL_I2CEx_ConfigDigitalFilter(&hi2c1, 0) != HAL_OK)
    {
        Error_Handler();
    }
}

/**
  * @brief UCPD1 Initialization Function
  * @retval None
  */
static void MX_UCPD1_Init(void)
{
    LL_GPIO_InitTypeDef GPIO_InitStruct = {0};

    /* Peripheral clock enable */
    LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_UCPD1);

    LL_IOP_GRP1_EnableClock(LL_IOP_GRP1_PERIPH_GPIOB);
    LL_IOP_GRP1_EnableClock(LL_IOP_GRP1_PERIPH_GPIOA);

    /**UCPD1 GPIO Configuration
    PB15   ------> UCPD1_CC2
    PA8    ------> UCPD1_CC1
    */
    GPIO_InitStruct.Pin = LL_GPIO_PIN_15;
    GPIO_InitStruct.Mode = LL_GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
    LL_GPIO_Init(GPIOB, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = LL_GPIO_PIN_8;
    GPIO_InitStruct.Mode = LL_GPIO_MODE_ANALOG;
    GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
    LL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}

/**
  * @brief GPIO Initialization Function
  * @retval None
  */
static void MX_GPIO_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct = {0};

    /* Enable GPIO clocks */
    __HAL_RCC_GPIOA_CLK_ENABLE();
    __HAL_RCC_GPIOB_CLK_ENABLE();

    /* Configure LEDs */
    GPIO_InitStruct.Pin = GPIO_PIN_7;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

    /* Configure I2C1 Pins */
    // PA9 = SCL
    GPIO_InitStruct.Pin = GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF6_I2C1;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    // PB9 = SDA
    GPIO_InitStruct.Pin = GPIO_PIN_9;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
}

/* USER CODE BEGIN 4 */
/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
    __disable_irq();
    while (1)
    {
    }
}

#ifdef USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line)
{
    // User can add implementation to report file name and line number
}
#endif