Re: A Simple Portable Packet Station for Emergency Communications


Richard Bates
 

On Wed, Jun 19, 2019 at 08:18 PM, Guillermo/Bill wrote:
Could you expand on the PTT part a little bit?
The DireWolf manual,  section 9.2.8.3, page 66, explains the addition you need in the direwolf.conf file, for example to use GPIO 26 you want

PTT GPIO 26

i.e. in this example, GPIO26 (pin #37) will go "high" when the software TNC wants to transmit.

This small reed relay fits conveniently inside the RPi case, and can be soldered directly to to GPIO line.

You can see that:
 - relay pin 1 connects to the radio PTT line
 - relay pin 2 connects to the GPIO line, pin 37 in this example
 - relay pins 3 and 4 connect to ground, for example pin 39

As I didn't need the functionality of the built-in RPi audio, I choose to disconnect the RPi audio-out lines from the built-in mini-jack, by breaking the tracks - so I could use it for the PTT line (relay pin 1).


You could alternatively simply add a mini-jack to the RPi case and take the PTT signal out that way.

Richard
 

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