STM32 讀取 BQ27541 電量

STM32 讀取 BQ27541 這是個人最近所接到的案子，要讀取電池包中的SOC，花了幾天終於完成了經驗總結如下：

TI bq27541 datasheet 對I2C介面的讀取如下圖，

                                                                        圖1 

我要採用的是(c) 1 byte-read,

用的是ST 範例程式 M24C08 EEPROM讀取的範例來寫：

用的是 MultiByteRead中這函式來讀取。

main 中用的是

I2C_EE_MultiByteRead(Rx1 ,0x2c, u16 NumByteToRead)   註 0x2c 是BQ27541讀取 SOC

           而圖1 的時序我把它拆成下面七個步驟

Host Generated		指令	Fuel Gauge Generated
1	Start,	I2C_GenerateSTART(I2C1, ENABLE);
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
2	ADDR[6:0] 0	I2C_Send7bitAddress(I2C1, 0xaa, I2C_Direction_Transmitter);	Acknowledge
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
3	CMD[7:0]	I2C_SendData(I2C1, (u8)ReadAddr);	Acknowledge
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
4	Start,	I2C_GenerateSTART(I2C1, ENABLE);
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
5	ADDR[6:0] 1	I2C_Send7bitAddress(I2C1, 0xab, I2C_Direction_Receiver);	Acknowledge
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
		for (i = NumByteToRead; i > 0; i--,pBuffer++)     { ……………………………….. }	DATA[7:0]
6	No Acknowledge	I2C_AcknowledgeConfig(I2C1, DISABLE);
		while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));
7	Stop	I2C_GenerateSTOP(I2C1, ENABLE);

 而在 i2c_ee.c 中的 void I2C_EE_MultiByteRead 的程式則被我改成如下：

void I2C_EE_MultiByteRead(u8* pBuffer, u16 ReadAddr, u16 NumByteToRead)

{ 

  u8 i = 0;

  /* Send STRAT condition */

  I2C_GenerateSTART(I2C1, ENABLE);

  /* Test on EV5 and clear it */

  while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT)); 

  /* Send EEPROM address for write */

  I2C_Send7bitAddress(I2C1, 0xaa, I2C_Direction_Transmitter);

 

  /* Test on EV6 and clear it */

  while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));

     

  /* Send the EEPROM's internal address to read from */

  I2C_SendData(I2C1, (u8)ReadAddr);

 

  /* Test on EV8 and clear it */

  while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));

  /* Send STRAT condition */

  I2C_GenerateSTART(I2C1, ENABLE);

  /* Test on EV5 and clear it */

  while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));

  /* Send EEPROM address for read */

  I2C_Send7bitAddress(I2C1, 0xab, I2C_Direction_Receiver);

 

  /* Test on EV6 and clear it */

  while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));

      for (i = NumByteToRead; i > 0; i--,pBuffer++)

    {

        if (i == 1)

                {

                I2C_AcknowledgeConfig(I2C1, DISABLE);

                 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED)); 

                *pBuffer = I2C_ReceiveData(I2C1);

                I2C_AcknowledgeConfig(I2C1, ENABLE);

                }

        else

            {

                I2C_AcknowledgeConfig(I2C1, ENABLE);

                 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED)); 

                *pBuffer = I2C_ReceiveData(I2C1); 

                i=i;

                }

    }

  /* Send STOP condition */

  I2C_GenerateSTOP(I2C1, ENABLE);

}


下面是我用網路上找的一個 GPIO 模擬 I2C 的讀取EEPRO 範例來修改 上面的字義更足以描述整個流程

 main 中用的是

I2C_ReadByte(Tx1_Buffer,   0x01,     0x2c,  0xAB);
--------------------------------------------------------------------------------------------

bool I2C_ReadByte(u8* pBuffer,   u8 length,     u16 ReadAddress,  u8 DeviceAddress)
{
 if(!I2C_Start())return FALSE;

    I2C_SendByte(0xAA& 0xFFFF);  //這是重點
    if(!I2C_WaitAck())
 {I2C_Stop();
      return FALSE;}
      I2C_SendByte(0x2c& 0x00FF));
    I2C_WaitAck();
     I2C_Start();
    I2C_SendByte(0xAB & 0xFFFF); //這是重點
    I2C_WaitAck();
    while(length)
    {
      *pBuffer = I2C_ReceiveByte();
      if(length == 1)I2C_NoAck();
      else I2C_Ack();
      pBuffer++;
      length--;
    }
    I2C_Stop();
    return TRUE;
}