STM32F100片外ADS1248，对寄存器操作不成功，求解…

ROO · 发表于 2013-3-8 16:33:11

代码如下

GPIO定义：
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_11; // SCLK、DIN、START
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; // DOUT
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; // DRDY
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_Init(GPIOB, &GPIO_InitStructure);

对寄存器操作如下：
void ADS1248WREG(unsigned char regaddr,unsigned char databyte)
{
ADS1248SPI(0x40+(regaddr&0x0F));
ADS1248SPI(0X00);
ADS1248SPI(databyte);
}

unsigned char ADS1248RREG(unsigned char regaddr)
{
unsigned char r=0X00;
ADS1248SPI(0x20+(regaddr&0x0F));
ADS1248SPI(0X00);
r=ADS1248SPI(0XFF);
return r;
}

unsigned char ADS1248SPI(unsigned char m)
{
unsigned char i,r=0;
for(i=0;i<8;i++) {
  ADS1248_SCLK(1);
  __NOP();__NOP();__NOP();__NOP();__NOP();
  r<<=1;
  if (m & 0x80) ADS1248_SADI(1);
  else ADS1248_SADI(0);
  __NOP();__NOP();__NOP();__NOP();__NOP();
  ADS1248_SCLK(0);
  __NOP();__NOP();__NOP();__NOP();__NOP();
  if (GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_9)>0) r++;
  __NOP();__NOP();__NOP();__NOP();__NOP();
  m<<=1;
}
return r;
}

执行AD寄存器写MUX0：
ADS1248WREG(0X00,0x01); // MUX0=00 000 001 = 0x01 AIN1
iads=ADS1248RREG(0X00);

CLK接GND，VREFOUT和VREFCOM接4.7uF，其它电路参照手册。
问题是，往寄存器写数据后，读出来的iads数为0X00，理论应该是0X01；用表和示波器均测得CLK、DIN有数据时电平变化，DOUT无电平变化，是否和代码有关，求解！

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