新手，关于I2C问题求教

只看该作者 · 2016-10-14 15:54

本帖最后由刀鱼于 2016-10-14 17:05 编辑

在调一个g2553板子工程，其中有用到I2C通信，写了一个I2C主机写多个字节的函数
问题是这样的，第一个字节被写入缓冲 UCB0TXBUF 之后，中断标志IFG2的 UCB0TXIFG 位被置0了。
正常情况下，不是收到STOP指令后中断标志UCB0TXIFG才被置0吗？
求大神指导！
下面是我的I2C主机写多个字节的函数：
static int8_t I2CSendBytes(uint8_t I2CSlaveAddress, uint8_t *DataBuffer, uint16_t ByteCount, uint16_t *SentByte)
{
uint16_t DelayCounter = 0;
uint16_t NumberOfBytesSent = 0;
uint8_t *DataPointer;

UCB0CTL0 |= UCMST;  // set master
UCB0I2CSA = I2CSlaveAddress;  // 从机地址

   DataPointer = DataBuffer;

   UCB0CTL1 |= UCTR; //data in transmit direction
   UCB0CTL1 |= UCTXSTT; //Generate Start Condition // UCB0TXIFG was set 1 automatically
                        //Send Start Byte

   while(!(IFG2 & UCB0TXIFG))  //if UCTXSTT != 0, wait here // wait until the slave acknowladged
   {
      DelayCounter ++;
      if (DelayCounter >= DELAY_LIMIT)
         break;
   }

   if (DelayCounter >= DELAY_LIMIT) //check if NACK condition occurred
   {
      *SentByte = NumberOfBytesSent;
      UCB0CTL1 |= UCTXSTP;
      return -1;
   }

   for(NumberOfBytesSent = 0; NumberOfBytesSent < ByteCount; NumberOfBytesSent++)
   {
      UCB0TXBUF= *DataPointer;  // 这一步执行后，中断标志UCB0TXFIG置0了

      DelayCounter = 0;

      while(DelayCounter < DELAY_LIMIT && (!(IFG2 & UCB0TXIFG) || (UCB0CTL1 & UCTXSTT)))  // 然后程序卡在这个循环里
      {
         DelayCounter++;
      }

      if (DelayCounter >= DELAY_LIMIT) //check if NACK condition occurred
      {
         *SentByte = NumberOfBytesSent;
         UCB0CTL1 |= UCTXSTP;             //send stop condition
         return -1;
      }

      DataPointer++;
   }

   IFG2 &= ~UCB0TXIFG;
   UCB0CTL1 |= UCTXSTP;    //send stop bit

   DelayCounter = 0;

   while(DelayCounter < DELAY_LIMIT && ((UCB0CTL1 & UCTXSTP)))  //check if the byte has been sent
   {
      DelayCounter++;
   }

   *SentByte =  NumberOfBytesSent;

   if (DelayCounter >= DELAY_LIMIT) //check if NACK condition occurred
   {
      UCB0CTL1 |= UCSWRST;
      return -1;
   }
   else
      return 0;
}