0 参考资料

FM24W256（Cypress公司生产）数据手册

1 基于HAL库实现硬件I2C读写

1.1 硬件I2C初始化

FM24W256支持最高1MHz的I2C频率，本例也配置为1MHz，相关初始化代码如下：

/**
 * @brief 使用硬件I2C的E2P初始化
 *
 * @return int 0：成功 -1：失败
 */
int bsp_i2c_e2p_init(void)
{
    u8 test_buff;

    /* 速度配置为1MHz，FM24W256支持最高1MHz速率 */
    hi2c1.Instance = I2C1;
    hi2c1.Init.Timing = 0x00401242;
    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(__FILE__, __LINE__);
        return -1;
    }

    /** Configure Analogue filter
     */
    if (HAL_I2CEx_ConfigAnalogFilter(&hi2c1, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
    {
        Error_Handler(__FILE__, __LINE__);
        return -1;
    }

    /** Configure Digital filter
     */
    if (HAL_I2CEx_ConfigDigitalFilter(&hi2c1, 0) != HAL_OK)
    {
        Error_Handler(__FILE__, __LINE__);
        return -1;
    }

    /*
        检查E2P是否能够正常读取
    */
    if (i2c_fram_read(&test_buff, 0, 1) != HAL_OK)
    {
        Error_Handler(__FILE__, __LINE__);
        return -1;
    }

    return 0;
}
/**
 * @brief I2C底层初始化
 *
 * @param hi2c I2C句柄
 */
void HAL_I2C_MspInit(I2C_HandleTypeDef *hi2c)
{
    GPIO_InitTypeDef GPIO_InitStruct = {0};
    RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
    if (hi2c->Instance == I2C1)
    {
        /* USER CODE BEGIN I2C1_MspInit 0 */

        /* USER CODE END I2C1_MspInit 0 */

        /** Initializes the peripherals clock
         */
        PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_I2C12;
        PeriphClkInit.I2c12ClockSelection = RCC_I2C12CLKSOURCE_PCLK1;
        if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
        {
            Error_Handler(__FILE__, __LINE__);
            return;
        }

        __HAL_RCC_GPIOD_CLK_ENABLE();
        /**I2C1 GPIO Configuration
        PD3     ------> I2C1_SDA
        PD12     ------> I2C1_SCL
        */
        GPIO_InitStruct.Pin = GPIO_PIN_3 | GPIO_PIN_12;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
        GPIO_InitStruct.Pull = GPIO_NOPULL;
        GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF5_I2C1;
        HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

        /* Peripheral clock enable */
        __HAL_RCC_I2C1_CLK_ENABLE();

        /* USER CODE BEGIN I2C1_MspInit 1 */

        /* USER CODE END I2C1_MspInit 1 */
    }
}

/**
 * @brief I2C底层去初始化
 *
 * @param hi2c I2C句柄
 */
void HAL_I2C_MspDeInit(I2C_HandleTypeDef *hi2c)
{
    if (hi2c->Instance == I2C1)
    {
        /* USER CODE BEGIN I2C1_MspDeInit 0 */

        /* USER CODE END I2C1_MspDeInit 0 */
        /* Peripheral clock disable */
        __HAL_RCC_I2C1_CLK_DISABLE();

        /**I2C1 GPIO Configuration
        PD3     ------> I2C1_SDA
        PD12     ------> I2C1_SCL
        */
        HAL_GPIO_DeInit(GPIOD, GPIO_PIN_3);

        HAL_GPIO_DeInit(GPIOD, GPIO_PIN_12);

        /* USER CODE BEGIN I2C1_MspDeInit 1 */

        /* USER CODE END I2C1_MspDeInit 1 */
    }
}

1.2 硬件I2C读取数据

/**
 * @brief 从铁电存储器读取n字节
 *
 * @param pBuffer 读取buffer
 * @param ReadAddr 读取地址
 * @param length 长度
 * @return int 0：成功 -1：失败
 */
int i2c_fram_read(uint8_t *pBuffer, uint16_t ReadAddr, uint16_t length)
{
    u8 addr_buffer[2];
    HAL_StatusTypeDef status = HAL_OK;

    /* 构造读取写入buffer */
    addr_buffer[0] = (ReadAddr >> 8) & 0xff;
    addr_buffer[1] = (ReadAddr >> 0) & 0xff;

    status = HAL_I2C_Master_Transmit(&hi2c1, EEPROM_ADDRESS, addr_buffer, 2, 100);
    if (status != HAL_OK)
    {
        return -1;
    }

    status = HAL_I2C_Master_Receive(&hi2c1, EEPROM_ADDRESS, pBuffer, length, 100);
    if (status != HAL_OK)
    {
        return -1;
    }

    return 0;
}

这里使用的是FM24W256的随机读取方式，时序图如下：

1.3 硬件I2C写入数据

/**
 * @brief 向铁电存储器写入n字节
 * 写入长度不得大于EEPROM_WRITE_MAX_LENGTH
 * @param pBuffer 写buffer
 * @param WriteAddr 写首地址
 * @param length 长度
 * @return int 0：成功 -1：失败
 */
int i2c_fram_write(uint8_t *pBuffer, uint16_t WriteAddr, uint16_t length)
{
    uint16_t i, j = 2;
    uint8_t write_buffer[2 + EEPROM_WRITE_MAX_LENGTH];
    HAL_StatusTypeDef status = HAL_OK;
    /* 单次写入长度超过限制 */
    if (length > EEPROM_WRITE_MAX_LENGTH)
    {
        return -1;
    }

    /* 构造写入buffer */
    write_buffer[0] = (WriteAddr >> 8) & 0xff;
    write_buffer[1] = (WriteAddr >> 0) & 0xff;
    for (i = 0; i < length; i++)
    {
        write_buffer[j++] = pBuffer[i];
    }

    status = HAL_I2C_Master_Transmit(&hi2c1, EEPROM_ADDRESS, write_buffer, 2 + length, 100);
    if (status != HAL_OK)
    {
        return -1;
    }

    return 0;
}

这里使用的FM24W256写入时序图如下：