[arm-allstar] FT-2900R COS Signal

Sat Mar 28 13:16:07 EST 2015

Joe,

 The URI pin 8 can be set to either a high or low active state.

If in simpleusb.conf  -  carrierfrom=usb    - it is active high.  A high would assert COS

If  - carrierfrom=usbinvert  - it is active low. A low would assert COS

Since attaching nothing to the URI DB25 or turning off the radio would result in a high condition on pin 8 and assert COS, due to the internal pullup, it is a good idea to use usbinvert,  active low, whenever you can.  In some case you can avoid this so you just have to be careful if you are connected to anyone that you don't disconnect things or turn the radio off.

In general this it is good practice to not disconnect things or turn the radio off because even in the  usbinvert mode spikes or stray RF from HF or another source could trigger COS.
73 Doug
WA3DSP
http://www.crompton.com/hamradio

From: joe at ad2dx.us
To: arm-allstar at hamvoip.org
Date: Sat, 28 Mar 2015 16:28:13 +0000
Subject: Re: [arm-allstar] FT-2900R COS Signal

Doug,
Does the URI COS pin 8 use + logic, so a high = USB and not USBINVERT? As for the buffer, I think the CMOS chips have a high fanout of 10 I think, so I shouldn’t need a buffer but I’ll certainly find out :-)
Thanks.

73
Joe - AD2DX

On Mar 28, 2015, at 2:41 AM, Doug Crompton <doug at crompton.com> wrote:

Joe,

 The URI cos input is blocked by a diode with a very weak pullup on the CM119 chip. So the high level could be any reasonable voltage up to 20-30 volts but it would usually never be that high. Usually around 12, 5V, or 3V depending on the radios logic level.
 It does not really matter as it is blocked by the diode. The thing that matters is that low is really low - zero volts or there about.

You probably would not have to buffer as the URI pin 8 has very little load. I guess experimentation is in order. 

73 Doug

WA3DSP

http://www.crompton.com/hamradio

From: joe at ad2dx.us

To: arm-allstar at hamvoip.org

Date: Sat, 28 Mar 2015 05:07:10 +0000

Subject: Re: [arm-allstar] FT-2900R COS Signal

Thanks Doug. I guess I need to understand COS a bit more. It appears that COS is a digital low or high (0V or +5V). I did find AF mute on a 16 pin DIP at pin12, so I guess I need to
 probe it with my logic probe while listening to squelch open and closed on a received signal.

I don't have a scope but I think my logic probe will give me enough info. I wonder if I have to buffer that signal if I try to use it as a COS line for the URI, if the URI loads that signal down too much, or if I can just take the signal right
 off that pin. I suspect no buffer would be needed.

Time to look at the URI schematic too...

Thanks.

Joe Lauricella, AD2DX
joe at AD2DX dot US
609-737-7064

From: arm-allstar-bounces at hamvoip.org [arm-allstar-bounces at hamvoip.org]
 on behalf of Doug Crompton [doug at crompton.com]

Sent: Friday, March 27, 2015 11:20 PM

To: BeagleBone Black ARM Allstar

Subject: Re: [arm-allstar] FT-2900R COS Signal

Joe,

 Check out the service manual - 

http://elektrotanya.com/yaesu_ft-2900r_sm.pdf/download.html

main unit schematic.  It looks like AF mute is a place to look. You will need to check levels with a signal. It is best to have a low (0 volt) signal on PL receive.

73 Doug

WA3DSP

http://www.crompton.com/hamradio

From: joe at ad2dx.us

To: arm-allstar at hamvoip.org

Date: Fri, 27 Mar 2015 21:52:25 +0000

Subject: [arm-allstar] FT-2900R COS Signal

Hi Folks,
Does anyone know where I can find the COS signal inside the Yaesu FT-2900R? I can get TX/RX audio, PTT and ground from the outside of the unit but I poured through the schematics and cannot locate COS.
Thanks in advance.

73
Joe - AD2DX

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