[App_rpt-users] URI active low?

mike at midnighteng.com mike at midnighteng.com
Tue Mar 1 09:27:55 EST 2016

I "think" the problem you are having has a simple fix.

I don't know the specifics on the DMK URI

but a PTT normally switches to ground when active does not mean that it is high
when inactive. It can "FLOAT". 0v and no ground when inactive.

The COR on the CAT1000 will be looking for a voltage when "INACTIVE" if you have
'active low' switch enabled. And without it, it will time-out.

You need to pull the PTT/COR line high with a 5v voltage and let the PTT pull it
low for active signal.

If you look at the CAT schematics, there is a test post for audio that you can hook
a small amplified speaker to and listen to the events on the cat1000 for better


> I am having some problems getting PTT action on a repeater I am converting from
> IRLP to Allstar.
> The DMK-URI is interfaced to the secondary port of a CAT-1000 controller.   And the
> controllers second port is configured as active low. There is a 10k pull-up
> resistor on the CAT controller's COR#2 line.
> URI    DMK-URI        CAT-1000    CAT-1000
> Pin 1    PTT        Pin 5    COR #2
> Pin 7    CTCSS DET   Pin 9    PTT #2
> Pin 8    COR DET
> Pin 20    GND        Pin 17    GND
> Pin 21    MIC IN AC   Pin 23    TX AUDIO #2
> Pin 22    LEFT OUT    Pin 12    Rx AUDIO #2
> And I am using these settings:
> eeprom=0
> hdwtype=0
> rxboost=0
> carrierfrom=usbinvert
> ctcssfrom=no
> txmixa=voice
> txmixb=no
> invertptt=0
> duplex=1
> plfilter=no
> deemphasis=no
> preemphasis=no
> rxaudiodelay=0
> Running asterisk -r shows that its supposed to be playing the time
> (etc), but it never keys.
> Suggestions welcome.
> Thanks
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