RaspberryPI and soundmodem PTT

Hi

I have looking solution on RaspberryPI with soundmodem how to do PTT if I don't have in my radio VOX. When I have use soundmodem on my laptop with linux kernel 2.x ten years ago but driver soundmodem support PTT via RS-232 which working very well with my IC-W2A. But I don't know how to do this on RPI ?
It is need modify soundmodem driver to possible setting the gpio pin for PTT ?? Maybe exist patch for this ?

73 Waldek sp2ong

Hi Waldek,

You mean
route sr1dsz polnet axudp d 'XNet Flexnet node'
(dsz instead of bsz...)

It seems that your system is not able to set up a link with SR1DSZ. Check first in your node, without starting flexd that the partner is accessible via ax.25 (also delete the files in /var/ax25/flexd):

C axudp sr1dsz

If it works, check if it provides flexnet routes using the 'D' command

This is how your flexd works, so any failure gere will lead to flexd not working.

Activate flend afterwards.

73s de Marius, YO2LOJ

Hello Waldek,

The RPi has one built-in serial port but in it's default mode, it only supports TX / RX and GND pins. That won't help you for PTT. Now, what you can do is invoke one of the RPi's alternative I/O mappings and at that point, you have full access to the flow control pins (specifically RTS) that most people use for PTT. Please note, the RPi is a 3.3v device with limited current so you'll probably need a level shifter to drive the PTT line on your radio.

http://lavalink.com/2012/04/more-on-raspberry-pi-serial-ports/

Ps. In addition to considering Soundmodem, have you heard of Direwolf? http://home.comcast.net/~wb2osz/ This soundcard TNC supports is being actively developed, supports multiple parallel decoders for off frequency signals, supports multi-bit correction, etc. None of those times is true of Soundmodem. Oh yeah.. and it has RPi binaries!

--David

Another solution would be to use a usb/RS-232 adapter to get a full fledged serial port.

don't have in my radio VOX. When I have use soundmodem on my laptop with linux kernel 2.x ten years ago but driver soundmodem support PTT via RS-232 which working very well with my IC-W2A. But I don't know how to do this on RPI ?

PTT ?? Maybe exist patch for this ?

Or a simple external vox unit such as http://www.electroschematics.com/283/simple-vox/ although I'd probably do away with the relay.

or this http://www.rason.org/Projects/basicvox/basicvox.htm

Ray vk2tv

Hi there,

You can use a USB to RS232 adapter. The PTT function will work in the same way as a built-in serial port.

Or you can modify a USB sound card to access a GPIO pin on the sound chip. This will work with CM108 sound chips and SSS1623 sound chips, but only if they are packaged chips. If they are covered with epoxy then you can not access the GPIO pin. Do a web search for "CM108 PTT" and you should get some more information.

I wrote some code which was included in soundmodem. It allows you to select CM108 GPIO and specify which bit should be turned on for PTT.

73,

Andrew
ZL3AME

Hi everybody,
There is also a different cheaper solution.
a) detach the serial console output from the UART pins of the gPIO board, as described in several RasperryPI documentation (google can find) : basically editing the /boot/cmdline.txt startup file...
b) modify, using a text editor (not the soundmodemconfig utility !), the soundmodem.conf file, setting /dev/ttyAMAO as PTT interface
c) run soundmodem as usual : it will direct the PTT signal on the CTS0 pin of the UART.
d) the CTS0 pin can be actually (RaspberryPI B+) associated to the GPIO pin 17 (BCM mode)when the pin mapping it's set in ALT3 MODE. The "ALT mode" (alternative pin mapping matrix in the RaspberryPI) switch can be easily made by different utilities (for example small "to be compiled" functions like gpio_alt.c, or alternative Python libraries like "pigpio library" or other, at the moment it's not managed by standard Python RPi.GPIO libraries ). It's then required to create a small script (Python or bash, able to switch off SAMBA, sets the GPIO17 in ALT3 mode and finally executes soundmodem : doing this the GPIO17 can easily drive one of the classic PTT interfaces without need of heavy and expensive RS232-to-USB HW interfaces.

Enjoy
Ugo Poddine