ADS1220_Reset();
Setup_ADS1220(ADS1220_MUX_AIN1_AVSS,//ADS1220_MUX_AIN1_AIN2,
ADS1220_OP_MODE_NORMAL,
ADS1220_CONVERSION_SINGLE_SHOT,
ADS1220_DATA_RATE_20SPS,
ADS1220_GAIN_1,
ADS1220_PGA_BYPASS,
ADS1220_IDAC1_DISABLED,
ADS1220_IDAC2_DISABLED,
ADS1220_IDAC_CURRENT_OFF,
ADS1220_VREF_EXT_REF0_PINS,
ADS1220_TEMP_SENSOR_OFF);
当AIN1输入为正时，代码最高位为1；当输入为负时，代码最高为0，跟手册上相反，不知是为什么
