STM8 ADS1115 硬件I2C 读数据有点问题

只看该作者 · 2013-10-15 10:17

本帖最后由 shuishuo615 于 2013-10-15 10:23 编辑

东拼西凑了下代码，
读ADS1115 的转换数据16位,MSB+LSB
调试现象：debug串口用watch功能第一次while（1）的数据有问题，第二次以后进while读出正常。
比如接了3v 在ain端口，第一次while出来的数据ConversionResult是0x3eff,第二进while次才是0x3e80为正确值。我是在最后一句程序处设置断点查看的。估计是不是在读完MSB后的操作不正确？反正第一次读LSB总是0xff，第二次就对了。。。。。附上程序，只有一个main.c

附上ADS的读数据时序

/**
  ******************************************************************************
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "stm8s.h"

/* Private defines -----------------------------------------------------------*/
#define ADS1115_ADDR       0x90
#define ADS1115_POINT_CONFIG_REG 0x01
#define ADS1115_POINT_CONVERSION_REG 0x00

/* Private function prototypes -----------------------------------------------*/
u8  AD_MSB,AD_LSB;
u16 ConversionResult;

/* Private functions ---------------------------------------------------------*/

void main(void)
{

  //void bsp_InitI2C(void)
{
      I2C->CR1 = 0x00;  //禁用I2C模块以初始化I2C模块
      I2C->CR2 = 0x04;  //应答使能
      I2C->FREQR = 10;  //输入时钟频率 10M
      I2C->OARH  = 0x40; //设置地址模式配置为1
      I2C->OARL  = 0x00; //做为从机时的7位地址
      I2C->ITR  =  0x00;  //禁止所有的I2C中断
      I2C->CCRH = 0x80; //快速模式I2C  快速模式 tlow/thigh = 2;
      I2C->CCRL = 12;  //400Khz 时钟速率
      I2C->CR1 = 0x01;  //启用I2C模块
}

// void ADS1115_Init(void)
{

      unsigned char Temp;
      I2C->CR2 |= 0x01;  //产生始起信号
      while((I2C->SR1&0x01)==0); //等待始起信号已发送
      I2C->DR = ADS1115_ADDR;
      while((I2C->SR1&0x02)==0); //等待接收到从ADS1115返回的ACK
      Temp = I2C->SR1;
      Temp = I2C->SR3; //读SR3寄存器，以清除标志位ADDR


      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->DR = ADS1115_POINT_CONFIG_REG;
      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->DR = 0x52; //MSB
      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->DR = 0x83; //LSB
      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->CR2 |= 0x02;  //产生停止信号

}


  /* Infinite loop */
  while (1)
  {
            //u16 ADS1115_Read_Conversion(void)
{
      unsigned char Temp;


      /*********************************************

            将寄存器指向读取转换结果寄存器0x00

      **********************************************/
      while(I2C->SR3 & 0x02); //等待总线空闲
      I2C->CR2 |= 0x01;  //产生始起信号
      while((I2C->SR1&0x01)==0); //等待始起信号已发送
      I2C->DR = ADS1115_ADDR;
      while((I2C->SR1&0x02)==0); //等待接收到从ADS1115返回的ACK
      Temp = I2C->SR1;
      Temp = I2C->SR3; //读SR3寄存器，以清除标志位ADDR


      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->DR = ADS1115_POINT_CONVERSION_REG;

      while((I2C->SR1&0x80)==0); //等待数据寄存器空
      I2C->CR2 |= 0x02;  //产生停止信号



      /*************************************************

         开始分别读取高8位和低8位

      **************************************************/


      //1.产生I2C始起信号
      while(I2C->SR3 & 0x02); //等待总线空闲
      I2C->CR2 |= 0x01;  //产生始起信号
      while((I2C->SR1&0x01)==0); //等待始起信号已发送

      //发送ADS1115器件地址+读操作
      I2C->DR = ADS1115_ADDR+0x01;
      while((I2C->SR1&0x02)==0); //等待接收到从ADS1115返回的ACK
      Temp = I2C->SR1; //读SR3寄存器，以清除标志位ADDR
      Temp = I2C->SR3; //读SR3寄存器，以清除标志位ADDR
      /*1115返回数据*/

      /*读高8位数据*/
      while((I2C->SR1&0x40)==0); //等待数据寄存器不为空BTF
      Temp = I2C->SR1; //读SR1寄存器，以清除标志位ADDR
      AD_MSB=0x00;
      AD_MSB=I2C->DR ;
      Temp = I2C->SR3; //读SR3寄存器，以清除标志位ADDR

      I2C->CR2 &= ~0x04;
      I2C->CR2 |= 0x02;

      /*读低8位数据*/
      while((I2C->SR1&0x40)==0); //等待数据寄存器不为空
      Temp = I2C->SR1;
      AD_LSB=0x00;
      AD_LSB=I2C->DR ;
      Temp = I2C->SR3; //读SR3寄存器，以清除标志位ADDR



      I2C->CR2 |= 0x04;
      I2C->CR2 &= ~0x08;

      /*计算转换结果*/
      ConversionResult = 0x0000;
      ConversionResult += AD_MSB;
      ConversionResult = ConversionResult<<8;
      ConversionResult += AD_LSB;


//       return ConversionResult;

}
  }

}

#ifdef USE_FULL_ASSERT

/**
  * @brief  Reports the name of the source file and the source line number
  * where the assert_param error has occurred.
  * @param file: pointer to the source file name
  * @param line: assert_param error line source number
  * @retval : None
  */
void assert_failed(u8* file, u32 line)
{
  /* User can add his own implementation to report the file name and line number,
   ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

  /* Infinite loop */
  while (1)
  {
  }
}
#endif

/******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE****/