[OZAPRS] IO PCB audio pTT etc

Warren_Brown warbn at telstra.com
Tue Jan 30 18:11:04 AEDT 2018

Hi Glen,

I see you have included some I/O
If it's not pushing the scope too much, could you include some interfacing for it eg, opto in and open collector transistor for out?
Any chance of an AtoD for monitoring of the 12v supply?


-----Original Message-----
From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Glen English VK1XX
Sent: Tuesday, 30 January 2018 17:19
To: ozaprs at aprs.net.au
Subject: Re: [OZAPRS] IO PCB audio pTT etc

Hi Matt

excellent  ideas ! will do. OK on the computer watchdog. yep can do that to cycle power.  so if the linux stops you dont have to go to site ot sort it out.

OK on FT230. and rs232 driver

on the droid (maybe pi) (same pins header I think) there is a bunch of peripherals and another uart which I thought could TX to a uart display (or I2C), and RXD 3.3V from a 3.3V GPS chip. the interrupt input is on the pcb for 1ppm if desired...

UPS of sorts. hmmm maybe a super capacitor. just needs ot go to an IRQ capable pin on gpio and halt

How longup time- 100mS ?

yeah BOM will be around $12

On 30/01/2018 5:04 PM, Matthew Cook wrote:
> Glen,
> I'd also suggest the following;
>   * pull the TX/RX of the FT230 into a RS232 driver to allow radio control
>   * Have some form of H/W monostable watchdog for the Pi (mostly
>     likely dump power)
>   * It would also be a good idea to have some form of UPS function
>     where it shutsdown the Pi or disables the radio (relay?) when the
>     supply volts are 10.5V or less (programmable ?)
> 73
> Matt
> On 30 January 2018 at 15:36, Glen English VK1XX 
> <glenlist at pacificmedia.com.au <mailto:glenlist at pacificmedia.com.au>>
> wrote:
>     Today I have done a schematic for a board to plug into either Pi
>     or Odroid, OR any platform with a USB for the usual requirements-
>     audio I/O , PTT, a uart  and some spare pins for GPSPPS etc
>     Before I finalize it, are there any requests ?
>     Currently :
>     40 pin header for direct connection of IO to Odroid or RPi for
>     GPS/UART/PTT/RX mute / IO
>     On board USB audio device (PCM2903) for TX/RX audio  (two channels
>     so can suit  IQ radio)
>     On board USB UART (FT230) for generating RTS for generating PTT,
>     and gives you a 3.3V serial port
>     On board 8-30V in to 5V DCDC converter. quiet.
>     HW watchdog on PTT
>     Some IO for ? (2 x analog in, 2 x uart 1 x I2C)
>     should be buildable for $30 or less. all easy SMT sizes.
>     the idea is you can plug USB audio , USB uart  for any platform,
>     or you can use the built in expansion header IO for PTT etc direct
>     on a suitable board. IE good for PC or good for Odroid/PI.
>     green pluggable header for radio interface.
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