openharmony中使用I2C

openharmony 使用 i2c 设置寄存器的值，来驱动相机解串器板。

• I2cMsg的数据结构（//drivers/hdf_core/framework/include/platform/i2c_if.h）

struct I2cMsg {
    /** Address of the I2C device */
    uint16_t addr;
    /** Address of the buffer for storing transferred data */
    uint8_t *buf;
    /** Length of the transferred data */
    uint16_t len;
    /**
     * Transfer Mode Flag | Description
     * ------------| -----------------------
     * I2C_FLAG_READ | Read flag
     * I2C_FLAG_ADDR_10BIT | 10-bit addressing flag
     * I2C_FLAG_READ_NO_ACK | No-ACK read flag
     * I2C_FLAG_IGNORE_NO_ACK | Ignoring no-ACK flag
     * I2C_FLAG_NO_START | No START condition flag
     * I2C_FLAG_STOP | STOP condition flag
     */
    uint16_t flags;
};

其中，flags 字段对应枚举类型：

enum I2cFlag {
    /** Read flag. The value <b>1</b> indicates the read operation, and <b>0</b> indicates the write operation. */
    I2C_FLAG_READ           = (0x1 << 0),
    /** 10-bit addressing flag. The value <b>1</b> indicates that a 10-bit address is used. */
    I2C_FLAG_ADDR_10BIT     = (0x1 << 4),
    /** Dma flag. The value <b>1</b> indicates that the buffer of this message is DMA safe. */
    I2C_FLAG_DMA            = (0x1 << 9),
    /** Non-ACK read flag. The value <b>1</b> indicates that no ACK signal is sent during the read process. */
    I2C_FLAG_READ_NO_ACK    = (0x1 << 11),
    /** Ignoring no-ACK flag. The value <b>1</b> indicates that the non-ACK signal is ignored. */
    I2C_FLAG_IGNORE_NO_ACK  = (0x1 << 12),
    /**
     * No START condition flag. The value <b>1</b> indicates that there is no START condition for the message
     * transfer.
     */
    I2C_FLAG_NO_START       = (0x1 << 14),
    /** STOP condition flag. The value <b>1</b> indicates that the current transfer ends with a STOP condition. */
    I2C_FLAG_STOP           = (0x1 << 15),
};

• 读取 i2c

int my_read_i2c(int argc, char* argv[])
{
  uchar busId = 1;
  DevHandle handle = NULL;
  int32_t ret = 0;
  struct I2cMsg msgs[2]; // 消息结构体数组
  int16_t msgs_count = 0;
  uint8_t wbuff[128] = { 0 };
  uint8_t rbuff[128] = { 0 };

  // 解析参数......
  // 打开i2c控制器
  handle = I2cOpen(busId);
  if (handle == NULL)
  {
    HDF_LOGE("%s: I2cOpen failed\n", __func__, busId);
    return -1;
  }
  // 设置msgs数组有效数目
  msgs_count = 2;
  // 初始化msgs[0]，该部分为主设备发送从设备的i2c内容
  msgs[0].addr = m_i2c_slave_address;
  msgs[0].flags = toI2cFlags(0,
                            m_i2c_flags_addr_10bit,
                            m_i2c_flags_read_no_ack,
                            m_i2c_flags_ignore_no_ack,
                            m_i2c_flags_no_start,
                            m_i2c_flags_stop);
  msgs[0].len = 1;
  wbuff[0] = m_i2c_reg_address; // 本案例的i2c从设备是第1字节是寄存器地址
  msgs[0].buf = wbuff; // 初始化msgs[1]，该部分为主设备读取从设备发送的i2c内容
  msgs[1].addr = m_i2c_slave_address;
  msgs[1].flags = toI2cFlags(1,
                            m_i2c_flags_addr_10bit,
                            m_i2c_flags_read_no_ack,
                            m_i2c_flags_ignore_no_ack,
                            m_i2c_flags_no_start,
                            m_i2c_flags_stop);
  msgs[1].len = m_i2c_read_data_length;
  msgs[1].buf = rbuff; // i2c数据传输，传输次数为2次

  ret = I2cTransfer(handle, msgs, msgs_count);
  if (ret != msgs_count) {
    HDF_LOGE("I2cTransfer(read) failed and ret = %d\n", ret);
    goto out;
  }

  printf("I2cTransfer success and read data length = %d\n", strlen((char *)rbuff));
  for (uint32_t i = 0; i < strlen((char *)rbuff); i++) {
    printf("rbuff[%d] = 0x%x\n", i, rbuff[i]);
  }

out:
  // 关闭i2c控制器
  I2cClose(handle);
  return ret;
}

• 写入 I2c

int my_write_i2c(int argc, char* argv[])
{
  uchar busId = 1
  DevHandle handle = NULL;
  int32_t ret = 0;
  struct I2cMsg msgs[2]; // 消息结构体数组
  int16_t msgs_count = 0;
  uint8_t wbuff[128] = { 0 };
  uint8_t rbuff[128] = { 0 };

  // 解析参数 ......

  // 打开i2c控制器
  handle = I2cOpen(busId);
  if (handle == NULL) {
    HDF_LOGE("%s: I2cOpen failed\n", __func__, busId);
    return -1;
  }

  // 写操作
  // 设置msgs数组有效数目
  msgs_count = 1;
  // 初始化msgs[0]，该部分为主设备发送从设备的i2c内容
  msgs[0].addr = m_i2c_slave_address;
  msgs[0].flags = toI2cFlags(0,
                            m_i2c_flags_addr_10bit,
                            m_i2c_flags_read_no_ack,
                            m_i2c_flags_ignore_no_ack,
                            m_i2c_flags_no_start,
                            m_i2c_flags_stop);
  msgs[0].len = 2;
  wbuff[0] = m_i2c_reg_address;
  // 本案例的i2c从设备是第1字节是寄存器地址
  wbuff[1] = m_i2c_reg_value;
  // 本案例的i2c从设备是第2字节是寄存器数值
  msgs[0].buf = wbuff;
  // i2c数据传输，传输次数为2次
  ret = I2cTransfer(handle, msgs, msgs_count);
  if (ret != msgs_count) {
    HDF_LOGE("I2cTransfer(write) failed and ret = %d\n", ret);
    goto out;
  }

  printf("I2cTransfer success and write reg(%d), data(%d)\n", m_i2c_reg_address,m_i2c_reg_value);
}

out:
  // 关闭i2c控制器
  I2cClose(handle);
  return ret;
}