[arm-allstar] Baofeng 888 mod update

[Doug Crompton]

As many of you know Devan, KD8MST is offering modification services for the 888 and sound FOB. I have been working with him on some experiments to help eliminate the problem of COS hangups when the radio is inadvertently turned off or somehow unpowered.

We determined that a 1K resistor to ground on the COS line coming from the 888 seems to stop this from happening. The 888 's COS goes high for active COS and thus you must have carrierfrom=usb  in simpleusb.conf.  Adding the 1K resistor ensures that the COS line will go low when the radio is powered down and not key the COS. Tests also show that the 888 still pulls this line to a solid high on signal with the resistor installed.

Also to simplify things both the TX and RX dropping resistors can be 10K.

Note this will NOT eliminate the COS keyup problem in cases where the radio can be disconnected from the sound FOB. Users have to be aware not to do this when connected. Also starting with version 1.02 of the code in beta mode there is a COS timer - rx_timeout  - that defaults to 5 minutes and can be set to a shorter time if desired by adding the command to the node section of rpt.conf.  See the readme link right below the 1.02 download. I would recommend setting this to 3-4 minutes in typical situations. Doing so means that in the event of a COS fault your node would only hang the circuit for that period of time and until the problem was cleared it would not reset. 

I will be adding a note about this to the 888 howto on the hamvoip.org website. 
73 Doug
WA3DSP
http://www.crompton.com/hamradio
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.hamvoip.org/pipermail/arm-allstar/attachments/20160906/9cdd3998/attachment.html>