[App_rpt-users] URI GPIO

[David McGough]

Scott,

The URI GPIO pins are connected to the DB-25 without any buffering, etc. 
They are 3.3V logic, but based on the datasheet are considered to be 5V 
tolerant.

You'll most likely need a level converter on each GPIO pin used to drive a 
CDM1250 pin. A simple open-collector or open-drain transistor buffer on 
each used GPIO pin will work nicely.

There are dozens of acceptable ways to accomplish the buffering. Here is
one sample schematic using an NPN bipolar transistor and includes LED's 
for visual feedback. Note that this circuit inverts the logic, so logic 0 
becomes 1 and vice-versa.

https://hamvoip.org/docs/ptt-driver-example.png


73, David KB4FXC



On Sun, 3 Jun 2018, Scott Weis wrote:

> Isn’t the URI 5v logic?
> 
>  
> 
> From: App_rpt-users [mailto:app_rpt-users-bounces at lists.allstarlink.org] On Behalf Of Bryan Fields
> Sent: Sunday, June 3, 2018 7:06 PM
> To: Users of Asterisk app_rpt <app_rpt-users at lists.allstarlink.org>
> Subject: Re: [App_rpt-users] URI GPIO
> 
>  
> 
> Do you have a buffer from the 3.3v to 5v logic?
> 
> --
> 
> Bryan Fields
> 
> M: +1-727-409-1194
> 
> 
> On Jun 3, 2018, at 18:27, Scott Weis <kb2ear at kb2ear.net <mailto:kb2ear at kb2ear.net> > wrote:
> 
> I'm trying to set up channel steering for a Motorola CDM1250 and have the
> radio working without a URI. If I ground the channel pins the channels
> change on the radio fine.  Now when I connect the pins to a URI-x gpio1
> gpio2 gpio5 and gpio6 It dosent seem to work. I have gpio1=out0 ,
> gpio2=out0, gpio5=out0, gpio6=out0 and when I do a *584=cop,61,GPIO5=1 or
> *585=cop,61,GPIO5=0  nothing seems to change on the URI, either state I see
> +5v on the URI. Should it not get pulled to ground?
> 
> Am I doing something wrong?
> 
> Thanks & 73
> de Scott KB2EAR
> 
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