[App_rpt-users] Remote Bases with 16 channel radios?

[David McGough]

Hi Skyler,

I've got some software for little motorola HC908 microcontrollers that
interfaces with the standard MaxTrac type radios. The software reads the
channel by intercepting the serial data going to the front panel LED
display. Then, it can change channels by pulsing the up/down channel
buttons. I originally wrote this code after learning I could not do
channel steering on pre-GM300 family radios, using the 16 pin accy
plug....I learned this little problem -after- buying a box full of radios.
Oops.

It's on my list to rewrite this code for RPi2 GPIO, unless someone else 
beats me to it, first!

73, David KB4FXC


On Wed, 10 Jun 2015, Skyler F wrote:

> Has anybody ever created a remote base with a radio like the SM120 16
> channel commercial radio? Would it be possible to use the URI to specify
> the channel I want to go to, for example, hooking a GPIO pin to the
> "channel -" button and hooking another to the "channel +" button? So if I
> am on channel 1 and want to go to 7, the GPIO for "chan +" would have to
> pulse 6 times.  That wouldn't be very reliable probably because there is no
> confirmation that you are actually on the right channel, but this is how I
> would do it:
> 
> When a channel change is requested, pulse 16 or more times on the "chan -"
> button to make sure it is on channel 1. Then count the + button up to the
> channel number you want to go to. That idea, however wouldn't work on the
> SM120 because going below channel 1 brings you back to 16.
> 
> Another idea I have is put one channel on a frequency reference (maybe
> those 150mhz re-broadcasts of radio stations?) and then find the channel
> you want based on that reference.
> 
> Another idea yet would be to use a few more GPIO pins to see which elements
> of the 7-segment displays are lit up and then make an estimate on which
> channel you currently are on.
> 
>  Any other ideas?
> 
> 
> 73
> Skyler kd0whb
>