Solved
I2C between two NUCLEO-F446RE boards
Hi, I am trying to use a Nucleo-F446re as master and another one as slave. But the master is probably being timed out (not sure). Can you guys please have a look at my code and configuration. Thanks in advance <3
My Wiring:
1. I connected PB8 & PB9 of both master and slave via direct wire as I used then as SCL and SDA
2. Connected GND of master and slave
My code:
Master code:
/* 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 */
#include "i2cMaster.h"
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
I2C_HandleTypeDef hi2c1;
UART_HandleTypeDef huart2;
/* USER CODE BEGIN PV */
char msgToSend[] = "MsgFromMaster";
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_I2C1_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
int sz = 50;
uint8_t sndData[50];
void writeData(uint8_t* msg, uint8_t len){
sndData[0] = len;
memcpy(&sndData[1],msg,len);
if(HAL_I2C_Master_Transmit(&hi2c1, (0x27 << 1), sndData, len+1, 10000) != HAL_OK){
sz = 100;
}
sz = -1;
}
/* 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();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_USART2_UART_Init();
MX_I2C1_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
writeData((uint8_t*)msgToSend,13);
HAL_Delay(1000);
/* 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};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLM = 16;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 2;
RCC_OscInitStruct.PLL.PLLR = 2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief I2C1 Initialization Function
* None
* @retval None
*/
static void MX_I2C1_Init(void)
{
/* USER CODE BEGIN I2C1_Init 0 */
/* USER CODE END I2C1_Init 0 */
/* USER CODE BEGIN I2C1_Init 1 */
/* USER CODE END I2C1_Init 1 */
hi2c1.Instance = I2C1;
hi2c1.Init.ClockSpeed = 100000;
hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
hi2c1.Init.OwnAddress1 = 0;
hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
hi2c1.Init.OwnAddress2 = 0;
hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
if (HAL_I2C_Init(&hi2c1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2C1_Init 2 */
/* USER CODE END I2C1_Init 2 */
}
/**
* @brief USART2 Initialization Function
* None
* @retval None
*/
static void MX_USART2_UART_Init(void)
{
/* USER CODE BEGIN USART2_Init 0 */
/* USER CODE END USART2_Init 0 */
/* USER CODE BEGIN USART2_Init 1 */
/* USER CODE END USART2_Init 1 */
huart2.Instance = USART2;
huart2.Init.BaudRate = 115200;
huart2.Init.WordLength = UART_WORDLENGTH_8B;
huart2.Init.StopBits = UART_STOPBITS_1;
huart2.Init.Parity = UART_PARITY_NONE;
huart2.Init.Mode = UART_MODE_TX_RX;
huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart2.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART2_Init 2 */
/* USER CODE END USART2_Init 2 */
}
/**
* @brief GPIO Initialization Function
* None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : LD2_Pin */
GPIO_InitStruct.Pin = LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* file: pointer to the source file name
* line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
Slave Code:
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Minimal I2C Slave Example with LED indication (Address: 0x27)
******************************************************************************
* This code sets up an I2C slave that waits for a transmission from a master.
* The master is expected to send N+1 bytes:
* - The first byte is the number of payload bytes (N)
* - Followed by N payload bytes.
* The onboard LED (LD2) will be lit when the slave is actively listening.
* When the master starts a transmission, the LED is turned off.
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
/* Private variables ---------------------------------------------------------*/
I2C_HandleTypeDef hi2c1; // I2C used for the slave
// Global reception buffer and state variables.
#define BUFFER_SIZE 50
uint8_t rxBuffer[BUFFER_SIZE]; // Buffer for incoming data.
volatile uint8_t rxPayloadLength = 0; // Expected payload length (first byte)
volatile uint8_t rxStage = 0; // 0: waiting for length, 1: receiving payload
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C1_Init(void);
/* USER CODE BEGIN 0 */
// For clarity, we'll define helper functions to set the LED state.
void LED_On(void)
{
HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_SET);
}
void LED_Off(void)
{
HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_RESET);
}
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* MCU Configuration--------------------------------------------------------*/
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_I2C1_Init();
// Enable I2C listen mode (interrupt based) so that the slave responds to address match.
if (HAL_I2C_EnableListen_IT(&hi2c1) != HAL_OK)
{
while(1);
}
// Turn the LED on to indicate the device is actively listening.
LED_On();
/* Infinite loop */
while (1)
{
}
}
/* --- I2C Slave Callbacks --- */
/**
* @brief Address Match Callback.
* Called when the slave address is matched.
* hi2c: Pointer to the I2C handle.
* TransferDirection: Direction requested by master.
* AddrMatchCode: Matched address.
* @retval None
*/
void HAL_I2C_AddrCallback(I2C_HandleTypeDef *hi2c, uint8_t TransferDirection, uint16_t AddrMatchCode)
{
if (hi2c->Instance == I2C1)
{
// Turn off LED when the master starts transmission (i.e. we're no longer just listening)
LED_Off();
if (TransferDirection == I2C_DIRECTION_TRANSMIT)
{
// Start reception: first, receive one byte (the length)
rxStage = 0; // Waiting for length byte.
if (HAL_I2C_Slave_Seq_Receive_IT(hi2c, rxBuffer, 1, I2C_FIRST_FRAME) != HAL_OK)
{
while(1);
}
}
else
{
// We do not support master reading from slave in this example.
while(1);
}
}
}
/**
* @brief Slave Reception Complete Callback.
* Called when the requested number of bytes have been received.
* hi2c: Pointer to the I2C handle.
* @retval None
*/
void HAL_I2C_SlaveRxCpltCallback(I2C_HandleTypeDef *hi2c)
{
if (hi2c->Instance == I2C1)
{
if (rxStage == 0)
{
// First byte (length) received.
rxPayloadLength = rxBuffer[0];
rxStage = 1;
if (rxPayloadLength > 0)
{
// Now receive the payload (rxPayloadLength bytes) in the last frame.
if (HAL_I2C_Slave_Seq_Receive_IT(hi2c, &rxBuffer[1], rxPayloadLength, I2C_LAST_FRAME) != HAL_OK)
{
while(1);
}
}
else
{
// If payload length is 0, re-enable listening.
if (HAL_I2C_EnableListen_IT(hi2c) != HAL_OK)
{
while(1);
}
// Turn the LED on again (active listening)
LED_On();
}
}
else
{
// Payload reception complete.
// (Data is now stored in rxBuffer[1] to rxBuffer[rxPayloadLength])
// Re-enable listen mode to accept the next transmission.
if (HAL_I2C_EnableListen_IT(hi2c) != HAL_OK)
{
while(1);
}
// Turn the LED on again.
LED_On();
}
}
}
/**
* @brief I2C Error Callback.
* Called when an error occurs.
* hi2c: Pointer to the I2C handle.
* @retval None
*/
void HAL_I2C_ErrorCallback(I2C_HandleTypeDef *hi2c)
{
if (hi2c->Instance == I2C1)
{
// Attempt to re-enable listen mode in case of error.
if (HAL_I2C_EnableListen_IT(hi2c) != HAL_OK)
{
while(1);
}
// Turn the LED on to indicate listening mode is re-established.
LED_On();
}
}
/* --- Peripheral Initialization Functions --- */
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLM = 16;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 2;
RCC_OscInitStruct.PLL.PLLR = 2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
while(1);
}
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK |
RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
while(1);
}
}
/**
* @brief I2C1 Initialization Function (Slave)
* None
* @retval None
*/
static void MX_I2C1_Init(void)
{
hi2c1.Instance = I2C1;
hi2c1.Init.ClockSpeed = 100000;
hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
hi2c1.Init.OwnAddress1 = 0x27; // Slave address set to 0x27
hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
hi2c1.Init.OwnAddress2 = 0;
hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
if (HAL_I2C_Init(&hi2c1) != HAL_OK)
{
while(1);
}
}
/**
* @brief GPIO Initialization Function
* None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* Enable GPIO clocks */
__HAL_RCC_GPIOB_CLK_ENABLE(); // Adjust if your I2C pins are on a different port.
__HAL_RCC_GPIOA_CLK_ENABLE(); // For LED if needed (depends on board)
/* Configure I2C1 SCL and SDA pins */
/* Adjust the pins if your board uses different ones */
GPIO_InitStruct.Pin = GPIO_PIN_6 | GPIO_PIN_7; // Example: PB6 (SCL) & PB7 (SDA)
GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF4_I2C1;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/* Configure LED pin (LD2) */
/* Adjust port/pin names to match your board's configuration */
GPIO_InitStruct.Pin = LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);
}
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
__disable_irq();
while (1)
{
// Stay here in case of error.
}
}
Can anyone please verify why my code is not working ? I am a beginner, trying to make it work for 3 days. I appreciate your attention. Thank you.
