Pmods also communicate with the host board through general purpose input/output (GPIO) pins. This does not follow a strict set of rules regarding how the Pmod and the host should communicate. Rather, the host is able to send high, low, pwm, analog, audio, or a variety of other signal types to the Pmod at any time and have the Pmod (more or less) immediately respond as designed which is great if you want to get a response whenever you press a button or flip a switch. The host could also receive the same variety of signals from the Pmod at any time, but it depends on how the code is designed to have the host respond to or ignore the signals. Also, because we are using input/output pins for communication, we can become rapidly limited in our capability to operate a large amount of peripheral modules.