Hello everyone,
I have been trying to open communications via I2C between the STM32G484RET6 and a MCP47FXDX8 DAC using the STM32CubeIDE toolchain.
However, as I struggled with that so much I took a step back and just tried to read the I2C data from a Nucleo-G474RE (thinking there was an issue with my aux circuitry for the RET6 surfboard). It seemed I was still not able to get anything on the logic analyzer (Analog Discovery Studio) out of the SDA & SCL lines.
I have the SDA & SCL lines pulled high (3.3V) using 5k resistors.
The code below shows what I have been trying.
The ret stats there is a "HAL_ERROR"
/* 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 <string.h>
#include <stdio.h>
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
// MCP47FEB18 I2C address (7-bit)
#define MCP47FEB18_I2C_ADDRESS 0x60
// Reference voltage (VREF)
#define VREF 3.3
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* 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);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
HAL_StatusTypeDef ret;
void MCP47FEB18_SetVoltage(uint8_t channel, float voltage) {
// Ensure voltage is within range (0 to VREF)
if (voltage < 0) {
voltage = 0;
} else if (voltage > VREF) {
voltage = VREF;
}
// Calculate DAC value for the given voltage
uint16_t dacValue = (uint16_t)((voltage / VREF) * 4095);
// Prepare data to send to MCP47FEB18
uint8_t data[3];
data[0] = channel; // Register address for the specified DAC channel
data[1] = (dacValue >> 8) & 0x0F; // Upper 4 bits of the 12-bit value
data[2] = dacValue & 0xFF; // Lower 8 bits of the 12-bit value
ret = HAL_I2C_Master_Transmit(&hi2c1, MCP47FEB18_I2C_ADDRESS << 1, data, sizeof(data), HAL_MAX_DELAY);
if (ret != HAL_OK){
strcpy((char*)data, "Error Tx\r\n");}
//// Transmit data over I2C2
//if (HAL_I2C_Master_Transmit(&hi2c2, MCP47FEB18_I2C_ADDRESS << 1, data, sizeof(data), HAL_MAX_DELAY) != HAL_OK) {
// Handle transmission error
// Error_Handler();
//}
}
/* 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_I2C1_Init();
/* USER CODE BEGIN 2 */
// Set DAC channel 2 (VOUT2) to 1.3V
MCP47FEB18_SetVoltage(2, 1.3);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
// Set DAC channel 2 (VOUT2) to 1.3V
MCP47FEB18_SetVoltage(2, 1.3);
HAL_Delay(2);
}
/* 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_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);
/** 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_NONE;
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_HSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != 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.Timing = 0x00503D58;
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();
}
/** Configure Analogue filter
*/
if (HAL_I2CEx_ConfigAnalogFilter(&hi2c1, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
{
Error_Handler();
}
/** Configure Digital filter
*/
if (HAL_I2CEx_ConfigDigitalFilter(&hi2c1, 0) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2C1_Init 2 */
/* USER CODE END I2C1_Init 2 */
}
/**
* @brief GPIO Initialization Function
* None
* @retval None
*/
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOB_CLK_ENABLE();
/* 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 */
Okay I got the Logic Analyzer (LA) to give me a usable output.
However, STMCube is still reporting a HAL_ERORR.
The lower plot is the scope showing that the output of the DAC is reporting 1.6V, as opposed to the 1.3V the code is instructing it to output.
The LA does show that the 1st dataframe is correct as it is composed of the [start bit | Slave Address | Write Bit | ACK ] but then the rest seems to fall apart.
The main change from not getting anything on the LA to what I am getting now was using the Nucleo's 3.3V and GND for the pull up resistors rather than the external 3.3V & GND from the Analog Discovery Studio.
Hi Bob S,
Thank you for taking a quick look. Your "channel" comment made me take a deeper look and that was indeed incorrect. I have correct that and removed the strcpy() and will be sure not to use it again. I have included a cleaned up version of my updated code.
// MCP47FEB18 I2C address (7-bit)
#define MCP47FEB18_I2C_ADDRESS 0x60
// Reference voltage (VREF)
#define VREF 3.3
#define numOfBits 1024
I2C_HandleTypeDef hi2c1;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C1_Init(void);
/* USER CODE BEGIN 0 */
HAL_StatusTypeDef ret;
void MCP47FEB18_SetVoltage(uint8_t channel, float voltage) {
// Ensure voltage is within range (0 to VREF)
if (voltage < 0) {
voltage = 0;
} else if (voltage > VREF) {
voltage = VREF;
}
// Calculate DAC value for the given voltage
uint16_t dacValue = (uint16_t)((voltage / VREF) * numOfBits);
// Prepare data to send to MCP47FEB18
uint8_t data[3];
uint8_t command = (channel << 4) | 0x00; // Command byte: Memory address (DAC Channel Reg) + write command (00)
data[0] = command;
data[1] = (dacValue >> 8) & 0x03; // Upper 2 bits of DAC value
data[2] = dacValue & 0xFF; // Lower 8 bits of DAC value
ret = HAL_I2C_Master_Transmit(&hi2c1, MCP47FEB18_I2C_ADDRESS << 1, data, sizeof(data), HAL_MAX_DELAY);
if (ret != HAL_OK){
Error_Handler();}
}
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* 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();
/* USER CODE BEGIN 2 */
// Set DAC channel 2 (VOUT2) to 1.3
MCP47FEB18_SetVoltage(0, 1.3);
HAL_Delay(2);
MCP47FEB18_SetVoltage(2, 1.3);
HAL_Delay(2);
MCP47FEB18_SetVoltage(4, 3);
HAL_Delay(2);
MCP47FEB18_SetVoltage(6, 1.3);
HAL_Delay(2);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
}
}
According to the LA this code has been outputting the correct I2C write sequence for channels 0, 2, 3, & 4 but not for channel 6.
The MCP47FEB18_SetVoltage function is shown below along w/ the device address for reference:
#define MCP47FEB18_I2C_ADDRESS 0x60
void MCP47FEB18_SetVoltage(uint8_t channel, float voltage) {
// Ensure voltage is within range (0 to VREF)
if (voltage < 0) {
voltage = 0;
} else if (voltage > VREF) {
voltage = VREF;
}
// Calculate DAC value for the given voltage
uint16_t dacValue = (uint16_t)((voltage / VREF) * numOfBits);
// Prepare data to send to MCP47FEB18
uint8_t data[3];
uint8_t command = (channel << 4) | 0x00; // Command byte: Memory address (DAC Channel Reg) + write command (00)
data[0] = command;
data[1] = (dacValue >> 8) & 0x03; // Upper 2 bits of DAC value
data[2] = dacValue & 0xFF; // Lower 8 bits of DAC value
ret = HAL_I2C_Master_Transmit(&hi2c1, MCP47FEB18_I2C_ADDRESS << 1, data, sizeof(data), HAL_MAX_DELAY);
if (ret != HAL_OK){
Error_Handler();}
}
Below are the function call, function variables, and the LA
MCP47FEB18_SetVoltage(0, 1.3);
MCP47FEB18_SetVoltage(2, 1.3);
MCP47FEB18_SetVoltage(4, 3);
Even so it does not look like it is causing the output of channel 4 to respond to the set voltages.
MCP47FEB18_SetVoltage(6, 1.3);
At this point I think that the mCU is behaving properly and I2C comms are up and running (excluding the oddity of channel 6).
On the target device side, as it is ACK'ing I want to say the I2C comms are being received correctly.
I am just not sure why it is not outputting the correct voltages.
