发送start命令有时可以正常的启动转换，有时则不能？

2万 · 2020-6-8 21:27

评估ADS1262,使用SPI 4线接口（CS,ADI,ADO,SCK）与STM32F103进行通讯，采用软件模拟时序，ADS1262的START pin通过一个3.9k电阻接地,RST/PWDN引脚通过一上拉电阻接电源。通过软件发送Start 命令来启动ADC的转换，
现遇到以下问题：发送start命令有时可以正常的启动转换，有时则不能？

1万 · 2020-6-8 21:30

时序问题

2万 · 2020-6-8 21:35

尝试将初始化值读出与写入值进行比较，貌似没问题

1万 · 2020-6-8 21:39

楼主程序可以公开吗？贴程序看下吧，这么说看不出什么原因

2万 · 2020-6-8 21:42

#define COMM_RESET       0X06                      //????
#define COMM_START       0X08                      //??????
#define COMM_STOP       0X0A                      //??????
#define COMM_READ_DATA 0X12                      //?????
#define COMM_SFOCAL1       0X19                      //?????
#define COMM_READ_REG    0X20                      //??????
#define COMM_WRITE_REG 0X40                      //??????

uchar bReady=0;
uchar read_reg_buffer[20];
signed long  ad_sample_dat;

void SPI_read_clock()
{
      ADS1262_SCLK=1;
      delay_us(15);
      ADS1262_SCLK=0;
      delay_us(15);
}

void SPI_write_clock()
{
      ADS1262_SCLK=0;
      delay_us(15);
      ADS1262_SCLK=1;
      delay_us(15);
}

/*===========================================================================================*/
//ADC????
uchar ad_read_byte()
{
      uchar i;
      uchar dat=0;
      ADS1262_DIN = 0;
      for(i=0; i<8; i++)
      {
            dat <<= 1;
            SPI_read_clock();             //???????????????,???????
            if(ADS1262_DOUT)
                     dat++;
      }
      return dat;
}

/*===========================================================================================*/
//adc????
void ad_write_byte(uchar dat)
{
      uchar i;
      for(i=0; i<8; i++)
      {
            if(dat & 0x80)
                     ADS1262_DIN=1;
            else
                     ADS1262_DIN=0;
            dat <<= 1;
            SPI_write_clock();
      }
}

/*===========================================================================================*/
//adc????
void ADS126x_Write_Register(uchar StartAddress, uchar NumRegs, uchar * pData)
{
      uchar i;
      ADS1262_CS = 0;
      //delay_us(1);
      ad_write_byte(COMM_WRITE_REG + StartAddress);
      ad_write_byte(NumRegs-1);
      delay_ms(10);
      for(i=0; i< NumRegs; i++)
      {
            ad_write_byte(*pData++);
      }
      ADS1262_CS = 1;
}

/*===========================================================================================*/
/*??????????????*/
void ADS126x_Read_Register(uchar StartAddress,uchar NumRegs,uchar *tab)
{
      uchar i;
      ADS1262_CS = 0;
      //delay_us(1);
      ad_write_byte(COMM_READ_REG+StartAddress);
      ad_write_byte(NumRegs-1);    /*?????????*/
      delay_ms(10);
      for(i=0; i< NumRegs; i++)
      {
            tab = ad_read_byte();
      }
      ADS1262_CS = 1;
}

/*===========================================================================================*/
unsigned long  ADS126x_ReadAdData()
{
      uchar i;
      uchar byte[4];
      ulong return_val;

      ADS1262_CS = 0;                         /*????*/
      //delay_us(1);
      //ad_write_byte(COMM_READ_DATA);          /*???????*/
      for(i=0; i<4; i++)
      {
            byte = ad_read_byte();
      }
      return_val = 0;
      if(byte[0] & 0x80)
      {
            return_val = 0xff;
            return_val = (return_val << 8) | byte[0];
            return_val = (return_val << 8) | byte[1];
            return_val = (return_val << 8) | byte[2];
      }
      else
      {
            return_val = 0x00;
            return_val = (return_val << 8) | byte[0];
            return_val = (return_val << 8) | byte[1];
            return_val = (return_val << 8) | byte[2];

      }
      ADS1262_SCLK = 0;
      ADS1262_CS = 1;
      ADS1262_DIN  = 0;
      ADS1262_DOUT = 0;

      return(return_val);
}

void ADS126x_SendResetCommand(void)
{
      ADS1262_CS = 0;
      ad_write_byte(COMM_RESET);
      ADS1262_CS = 1;
}

void ADS126x_SendStartCommand(void)
{
      ADS1262_CS = 0;
      ad_write_byte(COMM_START);
      ADS1262_CS = 1;
}

void ADS126x_SendStopCommand(void)
{
      ADS1262_CS = 0;
      ad_write_byte(COMM_STOP);
      ADS1262_CS = 1;
}

void ADS126x_Init(void)
{
      uchar tmp;


      tmp = 0x10;                                                                                                       //复位，偏置关闭，内部参考关闭
      ADS126x_Write_Register(0x01,1,&tmp);

      tmp = 0x00;                                                                                                       //关闭串口超时，关闭状态字节，关闭校验
      ADS126x_Write_Register(0x02,1,&tmp);

      tmp = 0x10;                                                                                                       //正常的参考电压极性，连续转换模式，斩波使能，转换0延时
      ADS126x_Write_Register(0x03,1,&tmp);

      tmp = 0x60;                                                                                                       //sinC4模式
      ADS126x_Write_Register(0x04,1,&tmp);

      tmp = 0x52;                                                                                                       //PGA=32,10SPS

      ADS126x_Write_Register(0x05,1,&tmp);


      tmp = 0x45;                                                                                                       //AIN4输入+AIN5输入-

      ADS126x_Write_Register(0x06,1,&tmp);

      tmp = 0x09;                                                                                                       //外部基准接AIN0,AIN1
      ADS126x_Write_Register(0x0F,1,&tmp);



}

void ADS126x_Reset(void)
{
      ADS126x_SendResetCommand();
      ADS126x_Init();
}

void ad_init(void)
{

      ADS126x_Reset();
      ADS126x_SendStartCommand();

}