2 Replies Latest reply on Sep 27, 2009 10:08 AM by user.38069901

    Best way to get AGND?

    user.38069901
              Since PSoC analog circuitry uses a virtual ground (AGND), what are some of the ways to bring out the "ground reference" for external circuitry, and to interface voltages referenced to system GND to the analog circuitry on the PSoC?   
         
      One way is to connect the AGND reference via a Refmux through a CT block and out an output buffer, but that uses up a resource.   
         
      I've brought AGND out on Port2_4 and buffered it externally.   
         
      For example, I would like to measure current out of a photodiode, but wanted a 'stiff' reference for making the measurement.   
         
      I'm also interested in sensing the drive current to a motor to detect stalls -- here, the current can be quite high, so I'll need a current-sensing resistor interfaced to the PSoC that would allow measurements to fall within the REFHI/REFLO range.