Implement EEPROM bytewise read/write

Core/Src/EEPROM.c

@@ -0,0 +1,71 @@
+#include "EEPROM.h"
+
+#include "main.h"
+
+#include "stm32f4xx_hal_def.h"
+#include "stm32f4xx_hal_i2c.h"
+
+EEPROM_State eeprom_state = EEPROM_OFF;
+
+I2C_HandleTypeDef* i2c;
+
+void eeprom_init(I2C_HandleTypeDef* handle) {
+  i2c = handle;
+  eeprom_state = EEPROM_READY;
+}
+
+HAL_StatusTypeDef eeprom_write(uint16_t addr, uint8_t data) {
+  uint8_t page = (addr >> 8) & 0b1;
+  uint8_t mem_addr = addr & 0xFF;
+  // Address must be shifted left for the HAL
+  uint8_t dev_addr = EEPROM_DEV_ADDR | (page << 1);
+
+  uint8_t msg[2] = {mem_addr, data};
+  return HAL_I2C_Master_Transmit(i2c, dev_addr, msg, 2, EEPROM_TIMEOUT);
+}
+
+HAL_StatusTypeDef eeprom_read_curr(uint8_t* data) {
+  return HAL_I2C_Master_Receive(i2c, EEPROM_DEV_ADDR, data, 1, EEPROM_TIMEOUT);
+}
+
+HAL_StatusTypeDef eeprom_read_random(uint16_t addr, uint8_t* data) {
+  // This is basically an SMBus Read Byte, see
+  // https://www.kernel.org/doc/html/latest/i2c/smbus-protocol.html#smbus-read-byte
+
+  uint8_t page = (addr >> 8) & 0b1;
+  uint8_t mem_addr = addr & 0xFF;
+  // Address must be shifted left for the HAL
+  uint8_t dev_addr = EEPROM_DEV_ADDR | (page << 1);
+
+  HAL_StatusTypeDef status = HAL_I2C_Master_Seq_Transmit_IT(
+      i2c, dev_addr, &mem_addr, 1, I2C_FIRST_FRAME);
+  if (status != HAL_OK) {
+    return status;
+  }
+
+  // Wait for write to be complete
+  while (HAL_I2C_GetState(i2c) != HAL_I2C_STATE_READY) {
+  }
+
+  // Try up to EEPROM_READ_TRIES times to get an acknowledgement from the slave.
+  // If we don't abort and return the error.
+  for (int i = 0; i < EEPROM_READ_TRIES; i++) {
+    status =
+        HAL_I2C_Master_Seq_Receive_IT(i2c, dev_addr, data, 1, I2C_LAST_FRAME);
+    if (status == HAL_OK) {
+      break;
+    } else if (HAL_I2C_GetError(i2c) != HAL_I2C_ERROR_AF) {
+      // Not an acknowledge failure -> timeout, abort
+      break;
+    }
+  }
+  if (status != HAL_OK) {
+    return status;
+  }
+
+  // Wait for read to be complete
+  while (HAL_I2C_GetState(i2c) != HAL_I2C_STATE_READY) {
+  }
+
+  return HAL_OK;
+}

Core/Src/main.c

@@ -22,6 +22,7 @@
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
 #include "BQ_Abstraction_Layer.h"
+#include "EEPROM.h"
 
 #include "stm32f4xx_hal.h"
 #include "stm32f4xx_hal_gpio.h"
@@ -139,6 +140,11 @@ int main(void) {
   HAL_GPIO_WritePin(DCDC_CTRL_GPIO_Port, DCDC_CTRL_Pin, GPIO_PIN_SET);
   HAL_Delay(100);
   afe_init(&huart2);
+  eeprom_init(&hi2c1);
+  uint8_t id;
+  if (eeprom_read_random(EEPROM_ADDR_SLAVE_ID, &id) == HAL_OK) {
+    HAL_GPIO_WritePin(STAT_LED4_GPIO_Port, STAT_LED4_Pin, GPIO_PIN_SET);
+  }
   /* USER CODE END 2 */
 
   /* Infinite loop */

Core/Src/stm32f4xx_hal_msp.c

@@ -246,6 +246,9 @@ void HAL_I2C_MspInit(I2C_HandleTypeDef* hi2c)
 
     /* Peripheral clock enable */
     __HAL_RCC_I2C1_CLK_ENABLE();
+    /* I2C1 interrupt Init */
+    HAL_NVIC_SetPriority(I2C1_EV_IRQn, 0, 0);
+    HAL_NVIC_EnableIRQ(I2C1_EV_IRQn);
   /* USER CODE BEGIN I2C1_MspInit 1 */
 
   /* USER CODE END I2C1_MspInit 1 */
@@ -277,6 +280,8 @@ void HAL_I2C_MspDeInit(I2C_HandleTypeDef* hi2c)
 
     HAL_GPIO_DeInit(GPIOB, GPIO_PIN_7);
 
+    /* I2C1 interrupt DeInit */
+    HAL_NVIC_DisableIRQ(I2C1_EV_IRQn);
   /* USER CODE BEGIN I2C1_MspDeInit 1 */
 
   /* USER CODE END I2C1_MspDeInit 1 */

Core/Src/stm32f4xx_it.c

@@ -57,6 +57,7 @@
 /* External variables --------------------------------------------------------*/
 extern CAN_HandleTypeDef hcan1;
 extern CAN_HandleTypeDef hcan2;
+extern I2C_HandleTypeDef hi2c1;
 extern UART_HandleTypeDef huart1;
 extern UART_HandleTypeDef huart3;
 /* USER CODE BEGIN EV */
@@ -228,6 +229,20 @@ void CAN1_RX1_IRQHandler(void)
   /* USER CODE END CAN1_RX1_IRQn 1 */
 }
 
+/**
+  * @brief This function handles I2C1 event interrupt.
+  */
+void I2C1_EV_IRQHandler(void)
+{
+  /* USER CODE BEGIN I2C1_EV_IRQn 0 */
+
+  /* USER CODE END I2C1_EV_IRQn 0 */
+  HAL_I2C_EV_IRQHandler(&hi2c1);
+  /* USER CODE BEGIN I2C1_EV_IRQn 1 */
+
+  /* USER CODE END I2C1_EV_IRQn 1 */
+}
+
 /**
   * @brief This function handles USART1 global interrupt.
   */