11 Replies Latest reply on Oct 10, 2015 2:31 PM by user_365962704

    Multiplexed 16ch ADC performance ideas

    danescu.andrei

      Hello, 

         

      I am looking to sample 16 inputs using the ADC and my PSoC5. I am looking for the most efficient and the fastest way to do this. 

         

      My current attempt is not working well - I tried to use an ADC_SAR_Seq block with 16 inputs. I am getting some values that are vaguely relevant but the performance is really really bad. 

         

      What I actually need is to sample different channels at different points in my main loop. Some need a Moving Average filter, some are fine as single sample. So I think I will need to implement a component based solution, i.e. a separate MUX and ADC.

         

      Signal wise: 

         

      0-5v input

         

      <10Hz sampling frequency required.

         

      Performance improvements:

         

      Decoupling RC on each pin - high frequency noise removal.  

         

      As I know from Step1 to Step2 what the next channel that  needs sampling is, I can preset the MUX and allow it to settle. 

         

      I can introduce a generic LPF between the MUX and ADC ( not sure how well this would work) using the highest frequency acceptable for my signals. 

         

      Do I need a PGA after the MUX, before the filter? Could probably use a unity gain amp there.  

         

       

         

      Thank you very much! 

         

      Andrei 

         

       

         

      Do you have any suggestions how to best implement this?