[arm-allstar] USB FOB Mods

[Doug Crompton]

Simon,

 No question is silly, well almost none, I do get a few. 

The way the external control will be done it will be possible to use the on board GPIO by writing a module to do it.  But there are a few reasons why that might not be a good idea. The Pi is 3V logic and you would have to make sure you did not exceed that. Also bringing leads from a far away external source to the Pi board could bring transients to the board. It could also lead to noise from the board getting into radio circuits. Another issue would be what GPIO pins do you use and how would that interfere with other devices possibly using them in a particular installation. There would be no standard that could be set for defined pins that would not have incompatibility in some situations. 

It would be up to the user to decide if these are issues for them but I personally feel a cleaner approach is to use a very inexpensive USB board such as the nano to supply gobs of I/O and not have to worry about any of the above issues.  
73 Doug
WA3DSP
http://www.crompton.com/hamradio


Date: Wed, 3 Aug 2016 13:24:52 +1200
To: arm-allstar at hamvoip.org
Subject: Re: [arm-allstar] USB FOB Mods
From: arm-allstar at hamvoip.org
CC: zl1oe.nz at gmail.com

Hi Doug

This is probably a silly question, but why can't we use GPIO for ptt/cos? 

Regards

Simon ZL1OE 

On 2/08/2016 2:13 pm, "Doug Crompton via arm-allstar" <arm-allstar at hamvoip.org> wrote:



I have changed the link for the sound FOB on the FOB Mod howto's. The old link was no longer valid. The new link shown should yield a good non potted FOB. While there are probably other links out there that are cheaper there is never any guarantee on any model that they are not potted but at least for now the one mentioned looks good. It uses a CM119A.

We have been talking about this for awhile but Dave is hard at work on the code for using other means to read and write PTT, COS and other bits independent of the sound FOBS. This will allow unmodified FOBS to be used along with another source for I/O. This will make it out in beta code in the near future. Maybe not the next beta but if not soon after. One of the current methods being tested is the Arduino Nano which is a <=$3 board available from numerous sources. It plugs into a USB port and supplies many I/O bits. A two node (two sound FOBS and Nano) system could be built for less than $10 for the sound and control interfacing. This would also allow many additional bits for other uses. Compare that to over $150 if you were using DMK-URI's. It has long been a source of contention that a user can buy a complete processor for $30 and then have to spend twice or more for a rather simple radio interface. For many this should solve that problem. 

73 Doug
WA3DSP
http://www.crompton.com/hamradio
 		 	   		  

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