[arm-allstar] COR timer -- was: COR question

[REDBUTTON_CTRL]

I believe the chip in the FOBS and the URI were designed to have the 
inputs pull hi internally and looks for a hi to lo transition to take 
action.

I dont want to spark the debate over weather active low vs active hi cor 
is better. The real answer is it shouldn't matter as long as you take 
into account what your connected radio does in all modes of operation.

Some radios only give a voltage change but dont pull to ground, some 
give an active lo, some have an open collector that either pulls to 
ground on signal or stays low and floats hi with signal.

In the case of active low (USBinvert) it should work most of the time, 
but as it has been said, in some radios the COR line goes low when the 
radio is turned off.
I have even seen some radios where the COR ling goes active on transmit too!

So if you switch to active hi (USB) then it should also work, and if the 
line goes low when the radio is turned off, then it shouldn't cause a 
problem. But if you disconnect your radio from the URI/FOB then it will 
think you radio is receiving and you are back to square 1.

Adding a timer may help but in my opinion it just masking the problem 
and it should be delt with in the radio.

I personally use USB invert (Active low) on all radios connected to 
repeater controllers and/or URIs.

I check the output signals on all the radios I intend to use and if I'm 
not satisfied that I can use an active low output then I modifiy the 
radio using an NPN transistor to give me and active lo open collector.

This way the COR line connected to the URI/FOB will always see an active 
lo COR or PL signal and the radio will never source any voltage whether 
its on or off or disconnected.

If you cant add the circuit and the radio does some unpredictable things 
with power glitches, then perhaps add  battery back up to the radio so 
it doesn't reset on power bumps and stays at its normal mode.

My point here is to ensure you investigate your radio and take the 
necessary precautions so that your node doesn't go into transmit mode 
for no reason.
Unfortunately this is a danger when setting up simplex nodes. If you 
node thinks its receiving a signal from your radio it will TX over the 
net to any connected nodes and cause them to TX and one may not know 
this is occurring.

just my 2 cents  worth. YMMV

Jon VA3RQ







On 12/16/2015 5:28 PM, David McGough wrote:
> Hi Guys,
>
> I'm not making promises, but, I'll take a look at adding an adjustable COR
> timer, functioning very much like the current "totime=xxx" for the TX
> timeout.
>
> I know this would be a VERY useful feature!
>
> 73, David KB4FXC
>
>
> On Wed, 16 Dec 2015, Doug Crompton wrote:
>
>> Yes, it definitely would be adjustable.
>> 73 Doug
>> WA3DSP
>> http://www.crompton.com/hamradio
>>
>>
>> From: ka5iid at swbell.net
>> Date: Wed, 16 Dec 2015 09:10:32 -0600
>> To: arm-allstar at hamvoip.org
>> Subject: Re: [arm-allstar] COR question
>>
>> Doug, if a timer is implemented please make it adjustable.
>> My guess is it would be specified as a receive active timer on the node. It would be reset every time the input toggled.
>> Stan
>>
>> Sent from my iPhone
>> On Dec 16, 2015, at 8:38 AM, Doug Crompton<doug at crompton.com>  wrote:
>>
>>
>
> Jim,
>>   The default is "usbinvert" only because it is configured for the Alinco, tyt etc. radios which go COS low on signal. If you have a radio that goes high on signal and you set it to "usb" you do have to be careful that you do not turn off or disconnect the radio. The CM108 has a pullup so it would put Allstar in an RXKEY condition and lockup a channel if you were connected anywhere. So the warning is to never turnoff or disconnect a radio especially in a connected state.
>>
>> This is a warning I always give new Allstar users. We are looking into a SW timer to lessen the issue whether it is intentional or unintentional.
>> 73 Doug
>> WA3DSP
>> http://www.crompton.com/hamradio
>>
>>
>> Date: Wed, 16 Dec 2015 03:02:17 -1000
>> From: jim.pilgram at gmail.com
>> To: arm-allstar at hamvoip.org
>> Subject: [arm-allstar] COR question
>>
>>    I'm wondering if there's a specific reason why negative on the COR was chosen rather than positive.
>> The reason ýI ask is we have had problems with node radios being turned off or power supplies tripping and timing out the system.
>> We are running mostly Motorola CDM750, 1250 and 1550's as simplex nodes and some repeaters. Most nodes are RPI2 or BBB'S
>> Can anyone she any light on this?
>> Jim NH6HI
>>
>>
>> Sent from my BlackBerry 10 smartphone on the Verizon Wireless 4G LTE network.
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