请教ADC采集中寄存器设置的相关问题

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请教ADC采集中寄存器设置的相关问题 [复制链接]

用的是PT100采集外部温度数据，属于模拟信号输入，选用的是P0.7口为模拟输入口。下面是我对ADC寄存器的设置，但是在线调试的时候，ADCH和ADCL里没有数值，不解，求高手指导！万分感谢！
void HalAdcInit (void)
{
#if (HAL_ADC == TRUE)
   volatile uint8  tmp;
   /*
   *  After reset, the first ADC reading of the extra conversion always reads GND level.
   *  We will do a few dummy conversions to bypass this bug.
   */
   tmp = ADCL;     /* read ADCL,ADCH to clear EOC */
   tmp = ADCH
   ADCCON3 = HAL_ADC_REF_VOLT | HAL_ADC_DEC_RATE | HAL_ADC_ECHN;//此处将ADCCON3初始化为0x8C。
   while ((ADCCON1 & HAL_ADC_EOC) != HAL_ADC_EOC);   /* Wait for conversion */

#endif
}

/**************************************************************************************************
* @fn      HalAdcRead
*RNDH
* @brief   Read the ADC based on given channel and resolution
*
* @param   channel - channel where ADC will be read
* @param   resolution - the resolution of the value
*
* @return  16 bit value of the ADC in offset binary format.
*          Note that the ADC is "bipolar", which means the GND (0V) level is mid-scale.
**************************************************************************************************/

uint16 HalAdcRead (uint8 channel, uint8 resolution)
{
   int16  reading = 0;

#if (HAL_ADC == TRUE)
   volatile  uint8 tmp;

  //Init P0.7
P0SEL |= 0x80; //配置 P0.7为外设
P0DIR |= 0x7F;//配置 P0.7口为输入模式
P0INP |= 0x80; //配置 P0.7为三态
ADCCON1 |= 0x1F;                    //选择ADC的启动模式为手动
ADCCON2 = HAL_ADC_REF_VOLT | HAL_ADC_DEC_RATE | HAL_ADC_SCHN;
   // Enable channel
  APCFG |= 0x80;

  //Convert resolution to decimation rate
  /*
   switch (resolution)
   {
     case HAL_ADC_RESOLUTION_8:
       resbits = HAL_ADC_DEC_064;
       break;
     case HAL_ADC_RESOLUTION_10:
       resbits = HAL_ADC_DEC_128;
       break;
     case HAL_ADC_RESOLUTION_12:
       resbits = HAL_ADC_DEC_256;
       break;
     case HAL_ADC_RESOLUTION_14:
     default:
       resbits = HAL_ADC_DEC_512;
       break;
   }
*/
   // read ADCL,ADCH to clear EOC
  tmp = ADCL;
   tmp = ADCH;

  // writing to this register starts the extra conversion
  ADCCON3 = 0x87;
   // Wait for the conversion to be done
  while (!(ADCCON1 & HAL_ADC_EOC));

  // Disable channel after done conversion
  //APCFG = 0x00;

  // Read the result
  reading = (int16) (ADCL);
   reading |= (int16) (ADCH << 8);

  // Treat small negative as 0
  if (reading < 0)
     reading = 0;

  switch (resolution)
   {
     case HAL_ADC_RESOLUTION_8:
       reading >>= 8;
       break;
     case HAL_ADC_RESOLUTION_10:
       reading >>= 6;
       break;
     case HAL_ADC_RESOLUTION_12:
       reading >>= 4;
       break;
     case HAL_ADC_RESOLUTION_14:
     default:
     break;
   }
#endif

  return ((uint16)reading);
}