0 Replies Latest reply on Aug 18, 2017 3:42 PM by issac.sharp

    Duty Cycle Varies with Frequency of Write

    issac.sharp

      Hi, I am new to PSoC programming, and I have encountered some confusing
      behavior. I have a PSoC5 LP device, and I'm trying to develop a parallel
      interface using a port on the device. I began testing my write speed by simply
      writing two alternating values on the port: specifically, I wrote 0x40 and 0x01
      to the correct register for P6. These values will alternate driving P6_6 high
      and P6_0 high. That is, while P6_6 is high, P6_0 is low, and vice versa. If I do
      this at a rather slow speed, I get a nice waveform that you'd expect from these
      pins, What is strange is that whenever I try to optimize the bus speed and clock
      speed to achieve an overall frequency somewhere above ~2MHz, I get a somewhat
      deformed duty cycle on both pins. So where before I'd have about a 50% duty
      cycle on both pins, now I have about a 33% duty cycle on one pin, and a 66% duty
      cycle on the other. Here are some images of the waveforms at the slow and high
      speeds, respectively: