cc2541 sensor 时序 i2c

只看该作者 · 2015-10-12 15:47

/**************************************************************************************************
* @fn       HalSensorReadReg
*
* @brief    This function implements the I2C protocol to read from a sensor. The sensor must
*             be selected before this routine is called.
*
* @param    addr - which register to read
* @param    pBuf - pointer to buffer to place data
* @param    nBytes - numbver of bytes to read
*
* @return    TRUE if the required number of bytes are reveived
**************************************************************************************************/
bool HalSensorReadReg(uint8 addr, uint8 *pBuf, uint8 nBytes)
{
  uint8 i = 0;

  /* Send address we're reading from */
  if (HalI2CWrite(1,&addr) == 1)
  {
/* Now read data */
i = HalI2CRead(nBytes,pBuf);
  }

  return i == nBytes;
}

第一张图是eeprom的读操作，然后上面的代码是TI 协议栈里的sensor的.  然后我看了下代码，里面的i2c时序和eeprom里datesheet的时序不一样。

TI显示的i2c时序是：

START -> device_write->write_byte_address->STOP

START -> device_read ->data_out -> NACK -> STOP

eeprom 的datesheet显示的i2c时序是：

START -> device_write->write_byte_address->write_byte_address->

START -> device_read ->data_out -> NACK -> STOP

2者的区别就是在read操作时，先要写一个byte地址（从哪开始读），TI是写完byte地址后STOP然后重新START

而eeprom datesheet里显示的是写完byte地址后，没有STOP,直接重新START.

so i think it should be START .... START ..... STOP

but it's START........STOP.......START.......STOP.

所以希望有能人异士给我解答下，应该如果下手。