Group I/O - Propeller C Learning System

KC9RXB

Hello everyone!

Radio shack put had a huge sale so I went on a little bit of a 'binge' and bought up all sorts of sensors and electronics in the region. Among those electronics was a Propeller quickstart board. I started going through the C tutorials (very good job as always, Parallax) and got to the part about controlling a 7-segment LED using the "set_directions" function.

I was wondering if there is a way to group several I/O pins that are not in order. For example I have 16 pins (1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31) but would still to be able to do something like this "set_outputs(15, 8, 0b11100111);"

Thank you,
Miles.K KC9RXB

jazzed

Hi there.

You could always use DIRA and OUTA statements. For example ...

#include <propeller.h>

int main()
{
  DIRA  = 0b1111; // set P0..3 pins to output and all other pins inputs
  DIRA |= 0b1111; // set P0..3 pins to output preserving state of other pins
  OUTA |= 0b0101; // set P0 and P2 high preserving state of other pins
}

KC9RXB

Unfortunately that wouldn't work for me because the pins are not contiguous

jazzed

KC9RXB wrote: »

Unfortunately that wouldn't work for me because the pins are not contiguous

But how would you do it otherwise?

The only way to set pin output states is by using DIRA and OUTA or through some counter output mode like video.

kwinn

Having non-contiguous pins will also make controlling the segments more difficult. You will need a word or long lookup table to do this.

jazzed

If you need a function to do set_outputs(15, 8, 0b11100111); on all odd pins, it is achievable. It won't be very fast though because a short algorithm would be used to set the appropriate bits based on the mapping. That is left to an exercise for the curious reader.