在
STM32f107基础上使用LTC1867芯片采样，设置单极性后只能采样要0~2V的电压，基准为4V。请大神帮忙！！！！
0~2V采样正常，2~4V读到的电压又从0开始递增。实际电压0V对应采集值0V,实际电压2V对应采集值为2V，2.01V开始就变成了0V，实际电压4V对应的采集值是1.996V。确认配置为单极性。[AppleScript]
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#define ADC_CS_H GPIO_SetBits(GPIOA,GPIO_Pin_4);#define ADC_CS_L GPIO_ResetBits(GPIOA,GPIO_Pin_4); #define ADC_SCK_H GPIO_SetBits(GPIOA,GPIO_Pin_5);#define ADC_SCK_L GPIO_ResetBits(GPIOA,GPIO_Pin_5); //#define ADC_MISO GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_6)#define ADC_MISO GPIOA->IDR&(1<<6) #define ADC_MOSI_H GPIO_SetBits(GPIOA,GPIO_Pin_7);#define ADC_MOSI_L GPIO_ResetBits(GPIOA,GPIO_Pin_7); #define Instruc
tions_LTC1867_CH0 0x80#define Instructions_LTC1867_CH1 0xC0#define Instructions_LTC1867_CH2 0x90#define Instructions_LTC1867_CH3 0xD0#define Instructions_LTC1867_CH4 0xA0#define Instructions_LTC1867_CH5 0xE0#define Instructions_LTC1867_CH6 0xB0#define Instructions_LTC1867_CH7 0xF0 #define LTC1867_SLEEP_MODE 0x02#define LTC1867_EXIT_SLEEP_MODE 0x00#define LTC1867_UNIPOLAR_MODE 0x04#define LTC1867_BIPOLAR_MODE 0x00 /****************************************** *功能：SPI初始化 *******************************************/void SPI_GPIO_Init(void){ GPIO_InitTypeDef GPIO_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE); //----------------------GPIO---------------------- // Configure SPI pins: CS GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); // Configure SPI pins: SCK GPIO_InitStructure.GPIO_Pin = 0; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_Init(GPIOA, &GPIO_InitStructure); // Configure SPI pins: MISO GPIO_InitStructure.GPIO_Pin = 0; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; GPIO_Init(GPIOA, &GPIO_InitStructure); // Configure _SPI pins: MOSI GPIO_InitStructure.GPIO_Pin = 0; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_Init(GPIOA, &GPIO_InitStructure); //设置为空闲状态 ADC_CS_H; ADC_SCK_H; } /************************************************ *功能： LTC1867ACGN选择1~8通道 *************************************************/u8 LTC1867ACGN_SetChnl(u8 chnl){ u8 cmd; switch(chnl) { case 1: cmd = Instructions_LTC1867_CH0|LTC1867_UNIPOLAR_MODE;break; case 2: cmd = Instructions_LTC1867_CH1|LTC1867_UNIPOLAR_MODE;break; case 3: cmd = Instructions_LTC1867_CH2|LTC1867_UNIPOLAR_MODE;break; case 4: cmd = Instructions_LTC1867_CH3|LTC1867_UNIPOLAR_MODE;break; case 5: cmd = Instructions_LTC1867_CH4|LTC1867_UNIPOLAR_MODE;break; case 6: cmd = Instructions_LTC1867_CH5|LTC1867_UNIPOLAR_MODE;break; case 7: cmd = Instructions_LTC1867_CH6|LTC1867_UNIPOLAR_MODE;break; case 8: cmd = Instructions_LTC1867_CH7|LTC1867_UNIPOLAR_MODE;break; default: cmd = Instructions_LTC1867_CH0|LTC1867_UNIPOLAR_MODE;break; } return cmd;} /********************************** *功能： SPI读写数据，给定通道选择参数 ***********************************/u16 SPI_WriteRead(u8 chnl){ u8 i = 0; u16 dat = 0; u8 cmd = 0; cmd = LTC1867ACGN_SetChnl(chnl); ADC_CS_L; delay_5us(10); //50 for(i=0;i<7;i++) { if(cmd&(0x80)) { ADC_MOSI_H; }else{ ADC_MOSI_L; } cmd <<= 1; ADC_SCK_L; delay_5us(1); //5 ADC_SCK_H; delay_5us(1); //5 } ADC_CS_H; delay_5us(2); //10 ADC_CS_L; for(i=0;i<16;i++) { ADC_SCK_L; delay_5us(1); //2 if(ADC_MISO) dat |= 1; dat <<= 1; ADC_SCK_H; delay_5us(1); //2 } ADC_CS_H; return dat;}
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