April 2021 – Page 3 – Kev's Development Toolbox

I’ve posted before about using a VT132 terminal board to control a PK-232 packet TNC. Here’s a few more specific steps and commands.

On first startup after doing the * auto-baud detection, the first thing you’ll see is the “cmd” prompt. If this is your first time setting up, or if the internal battery is low and it’s not preserving your settings since last time, the first thing you’ll want to do from the cmd: prompt is set your callsign (set your own callsign here):

my KK6DCT
MYcall was PK232
MYcall now KK6DCT

If you’re working VHF packet, turn on VHF mode, with:

VHF ON

If it was off, now it’s on.

Set baud to 1200 for VHF packet:

HB 1200

Now enter D to disconnect, and we’re ready to send some packets. To re-enter this command mode, press Ctrl C.

By default the PK232 has a MPROTO value of OFF which doesn’t display any received packets other than those sent to your callsign. Set MPROTO ON and you’ll display other packets heard.

Additionally, the default value of MON as 4 will show some but not all packets. Set MON 6 to display all packets decoded. If you’re hearing other packets but they’re still not being decoded, enter WHYNOT ON to get an explanation.

At this point you’re ready to go. C NODENAME to connect to a nearby node!

It’s been a few years since I last played with Packet Radio on a Raspberry Pi, but I have been playing with the uz7ho soundcard software recently and have some packet APRS via the International Space Station.

Looking back at the Direwolf and ax25 setup I was playing with before, I couldn’t actually remember what the order of commands was to get things started up, despite still having it all still configured and installed on the same Pi that I used before. Assuming ax25 and Direwolf are installed and configured (see here and here), the steps to get ax25 up and running and connected are:

Start direwolf with: “direwolf -t 0 -p”
Note the /dev/pts/x value it returns on startup
Run: “sudo kissattach /dev/pts/1 1” (where /dev/pts/1 matches the same value from direwolf startup)
The second 1 is the network name from your axports file, like:

1 KK6DCT-5 19200 255 2 2m packet

Ensure direwolf.conf has the same callsign-ssid value, in my example here, KK6DCT-5

Ensure alsamixer has volume around 3/4 for your audio card

To find what audio card device you’re using, use: “axplay -l”. With a Signalink, this shows up as:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

The Signalink is card 1, subdevice 0, so the corresponding config in direwolf.conf for this device is:

ADEVICE plughw:1,0

To summarize:

Start direwolf, grab the /dev/pts/x value
Start kissattach with the same /dev/pts/x value
Now you should be able to “call 1 nodename” and get a packet connection out via Direwolf to your radio.

Month: April 2021

Working Packet Radio with a VT132 and a AEA PK-232

Revisiting Packet Radio on a Raspberry Pi using Direwolf