use AFE module, found that the voltage input differential voltage and the calculated value is different, the difference of about 13%. For example, into a differential signal 200mV, read out from the results of balance device value is 3175931, then the calculated results should be 227mv (3175931/8388607 (0x7FFFFF) * 600 (MV) = 227mv), so the measured value is 227mv butinto value is 200mv. and therefore the result is wrong. Don't know why