2 Replies Latest reply on May 2, 2018 10:33 AM by junya_3267881

    8-Channel ADC_SAR_SEQ, last 4 channels cannot read low voltages

    junya_3267881

      Hi All,

       

      I'm trying to use the 8-channel ADC_SAR_SEQ on the CY8CKIT-042-BLE development kit. I can get appropriate ADC measurement readings for the first 4 channels, but the ADC cannot read voltages 0-995mV on channels 4 (P3[4]) & 5 (P3[5]), and cannot read voltages 0-311mV on channels 6 (P3[6]) & 7 (P3[7]). I am using a benchtop supply to feed the input voltage directly into the ADC_SAR pins through (P3[0]-P3[7]).

       

      I'm using the following ADC configurations:

       

      Vref Select: External Vref

      Vref Value: 2.5V

      Single ended negative input: Vref

      Single ended result format: Unsigned

      Clock source: Internal

      All 8 channels use 12-bit resolution single-ended mode

      Acq time: 1.5us

      Conversion time 16us

       

      Do you have any idea what could be preventing the last 4 channels from reading the low voltages? Thank you very much for your time!