2 Replies Latest reply on Aug 30, 2018 12:23 PM by MaLo_1836446

    ADC 5v accuracy


      Hello all,


      I am using a PSoC 4 BLE Kit



      I am doing a simple lab to teach my class about ADCs and Photo resistors and how to view the ADC result in putty.



      sprintf( output, "I am reading = %d mV \n", mVolts );





      I have everything working, however I noticed that my output was capped at 1024mV, I learned this was because on my ADC Block i had the VREF set at the 1.024 Volts ByPassed. I changed this to VDDA, which was set in the system at 3.3 but I was supplying it with 5. So when I programmed it, it capped out again at ~3000mV. So I went into the system and changed VDDD,VDDA,VDDR to 5V, now when I programmed it my values are off. When my multimeter reads about 700mV the PSOC reads about 1200mV, also when I shine a light on my photoresistor PSOC says it reads 5000mV when my multimeter reads about 4000mV. Is there some setting in the ADC SAR SEQ block I need to fix to get the accuracy back? or should I just power it with 3.3v which was just as accurate as the multimeter.


      Thank you for your time in helping me