STM32 HAL - writing to EEPROM (I2C)
I'm learning to program in HAL and today I wanted to save some data to an external I2C EEPROM. The problem is that I cannot get the EEPROM to send an ACK after I send the address. I tried it using an Arduino (on 5V and also 3V) and the IC responded with an ACK. I tried to connect an MLX90614 I2C IR sensor and it worked fine (I got the response and I could send and receive data both in Arduino and STM32). I also swapped the SDA and SCL leads thinking that I might have mixed them, but this was not the case. I used a logic analyzer and as You can see I got only an NACK. I don't think that the EEPROM IC (ATMLU036/2EB - AT24C256B) doesn't like 3V because it worked in Arduino and the datasheet says that it will work fine even at lower voltages. I have no clue why it is not working and why other I2C peripherals (such as IR sensor) worked just fine. I am using STM32F429ZI - DISC1. Here is my code: (in short I used pins PB8 for SCL and PB9 for SDA, I tried 100kHz, 10kHz, 1kHz scl frequency, but it didn't help. In STM32CubeMX I didn't change anything - the lines have internal pull-up resistors)
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "stm32f4xx_hal.h"
/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private variables ---------------------------------------------------------*/
I2C_HandleTypeDef hi2c1;
/* USER CODE BEGIN PV */
/* Private variables ---------------------------------------------------------*/
/* 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 */
/* Private function prototypes -----------------------------------------------*/
/* USER CODE END PFP */
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point.
*
* @retval None
*/
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 */
uint8_t d = 0xfc;
HAL_I2C_Mem_Write( &hi2c1, (0b1010000 << 1), 0x00, I2C_MEMADD_SIZE_8BIT, &d, I2C_MEMADD_SIZE_8BIT, 1000 );
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1){
/* 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;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
/**Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
/**Initializes the CPU, AHB and APB busses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = 16;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
/**Initializes the CPU, AHB and APB busses 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(__FILE__, __LINE__);
}
/**Configure the Systick interrupt time
*/
HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
/**Configure the Systick
*/
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}
/* I2C1 init function */
static void MX_I2C1_Init(void)
{
hi2c1.Instance = I2C1;
hi2c1.Init.ClockSpeed = 10000;
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(__FILE__, __LINE__);
}
}
/** Pinout Configuration
*/
static void MX_GPIO_Init(void)
{
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOB_CLK_ENABLE();
}
/* USER CODE BEGIN 4 */
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @param file: The file name as string.
* @param line: The line in file as a number.
* @retval None
*/
void _Error_Handler(char *file, int line)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
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.
* @param file: pointer to the source file name
* @param 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,
tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/**
* @}
*/
/**
* @}
*/
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
I have read somewhere, that this might be caused by the IC writing something, but in my example it isn't. I just wanted the device to answer, I didn't write anything to EEPROM cells. I have also written a simple I2C address scanner (for STM32 and I tried an Arduino I2C address scanner) and it's the same story: IR sensor responded with ACK (on address 0x5A) and EEPROM responded with NACK on every possible 7-bit address :\ (also on 0x50, the A0, A1, A2 address pins are tied to GND, I also tried it with external pull-up resistors, but as You can guess, It didn't work). Please help me or give me a hint why this setup is not working. I2C data transmission
Sorry for my grammar mistakes, I'm still learning English.
Answer
I think that I have found the answer. And the problem was: (drum rolls) huge capacitance. I plugged SDA and SCL into my oscilloscope and I saw this. Then I unplugged SDA and SCL cables from my breadboard and inserted them directly into oscilloscope. (Some buses are low at start, because I restarted STM32). After this I added 1K pull-up resistors (instead of the built into STM32 and (in testing) external 10K) and got this nice data transmission. Next I confirmed that everything works using PulseView. Thanks to everyone that have read my problem and spend some time tinkering why this was not working. I guess that MLX90614esf is less sensitive to big capacitance (or it has lower value resistors for internal pull-up).
