12 button wireless transmitter/receiver

Discussion in 'Wireless & RF Design' started by nickorossa, Sep 24, 2016.

  1. nickorossa

    Thread Starter Active Member

    Jun 28, 2010

    I have a bank of 12 switches from which I want to transmit a signal about 2-3 feet. The transmitter will be a hand held device powered by batteries. The buttons are all push to make non latching and I don't need to maintain state at the receiving end. Only one button would be pressed at a time.

    The receiver will ultimately back off onto a Raspberry Pi also powered off batteries. The receiver will be inside some plastic armour for a Cosplay costume. The pressed buttons would simply trigger functions on the RPi such as play a sound effect or take a picture. The coding on the RPi and reading state from the GPIO pins I'm fine with.

    I've come across a few examples, but the number of channels (switches supported is less than I need).

    The closest that I have found is this which does 8 switches.

    On the transmitter side I'm struggling to identify the IC 74147 in order to determine if it would support more switches that the 8 listed.

    The HT12E and HT12D, I think are 4 bit data; which I think means would support up to 16 combinations (thus 15 switches and off).

    I'm thinking that since only one button is pressed at a time and they are non latching, I'm thinking the buttons could be directly connected to the HT12E for transmit. Each button would send a unique combination to the 4 data bits. I'm thinking signal diodes would ensure each button sends a unique combination. On the receiving end; the 4 data bits could be connected to 4 GPIO pins on the RPI (via transistors) to give the unique coding back, and then decoded in software to determine which button was pressed.

    It would be useful to know your thoughts and if there are better ways to do what I want.


  2. KJ6EAD

    Senior Member

    Apr 30, 2011
  3. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
  4. nickorossa

    Thread Starter Active Member

    Jun 28, 2010
    Thanks for the links.
    However the transmitter would need rebuilding to fit with the object and its switches that will be held since it be spherical.

    Would prefer to build something really.