[OZAPRS] Raspbery Pi (RPi) Gateway

[roxbyplus]

I had it running a while back and seems ok. Like yourself I have yet to add the radio port but I think I will soon. Thanks for reviving my interest.



Sent from my Telstra Next G deviceRay Wells <vk2tv at exemail.com.au> wrote:All,

For somewhere around two years or so I'd been searching for a computer 
with low input energy requirements to use as a gateway machine to 
replace a conventional desktop system. And then I moved location quite 
suddenly which threw my plans into chaos. I'm now in a position to 
reestablish gateway facilities with 2m, 30m and satgate facilities, as 
per my original gateway.

Although I'd looked at the RPi (http://www.raspberrypi.org/) as a 
suitable computer, it was Bernard F6BVP (maintainer of xfbb and fpac) 
reporting that he had compiled a kernel with ax25 support that got me 
really interested. The latest Debian kernel - 
2012-08-16-wheezy-raspbian.img -has kernel ax25 included.

The RPi is a single board computer using a 700MHz ARM processor. It runs 
from a single 5V supply. The PCB is about the size of a credit card, has 
HDMI and composite video out, audio out, one ethernet port and 2 x USB 
ports. They are available from Element 14 (rebadged Farnell) and RS 
Components for about $38. See the wiki at 
http://en.wikipedia.org/wiki/Raspberry_Pi

My original intent was to run soundmodem to provide two 1k2 ports but I 
found soundmodem unstable and unpredictable on both the RPi and my 
desktop environment. In addition, the RPi failed to boot with a Sound 
Blaster Play USB dongle plugged in. The dongle is supposed to work OOTB 
on the RPi. Other users have reported similar boot problems.

Given that I still have a number of MFJ1270B TNCs I decided that a 
hardware approach might be more feasible in the short term. They can 
always be replaced by more efficient newer options (TNCX, TT4, etc) in 
the fullness of time. In order to run hardware TNCs I needed RS232 ports 
so a USB/RS232 adapter was needed. A recommendation from the xastir 
mailing list suggested a 4 port FTDI adaptor from DigiKey, at this 
address - 
http://www.digikey.com/product-detail/en/USB-COM232-PLUS4/768-1034-ND/2139296 
The unit cost about $76 with freight and arrived in four days from the 
US. I plugged it into the RPi and it worked OOTB. The adapter doesn't 
have a case, but neither does the RPi.

Because the gateway system will be away from the house I needed wifi for 
Internet access - too difficult to get Cat5 to the shed. I bought a 
TP-LINK TL-WN721N USB dongle and it almost worked OOTB. I needed to 
install wicd to be able to configure it but it works a treat. In the end 
I decided to use my Realtek 8189 equivalent wifi modem for the RPi 
because it has an external antenna. It just worked OOTB as well.

The RPi reliably boots with both the USB/RS232 adapter and the wifi 
dongle connected.

The software I had previously used for the gateway machine is xastir. 
It's always done the job and it's stable. The RPi will run headless and 
even though I don't "really" need the graphical display of xastir I was 
intent on giving it a try. Although there is now a deb package for 
xastir (with a current version), I opted to compile xastir on the RPi. I 
had already compiled the kernel ax25 surces for libax25, ax25apps and 
ax25tools.

Although the Raspian distribution is based on Debian Wheezy, not all 
packages are available for the ARM processor - yet. This led to some 
dependency conflicts that I eventually resolved by seeing what libraries 
had been used in the deb package. I finally managed to compile xastir 
with all options except festival sound, which I don't need. When I 
booted xastir it reported being unable to find libax25.so.1, even though 
it exists in /usr/local/lib. For whatever reason, xastir was looking in 
/usr/lib so I created a symlink - problem solved.

Xastir is understandably slow when loading raster maps (but lots faster 
than xastir 1.4 on a P166 machine some years ago!). For my trial I use 
just one map so speed is not an issue. A final installation may have no 
map loaded. Xastir is now running as vk2tv-4 but without radio ports at 
this stage until I assess reliability. I don't expect any issues.

During my enquiries on the xastir mailing list it was suggested that 
xastir is not ideal for a gateway machine (read that previously) and 
that I should try aprx which works in a non-graphical environment. I've 
also compiled a deb package for the ARM processor and it installed just 
fine. aprx has some very flexible configuration options and it reports 
lots of statistics on channel usage, etc, as telemetry beacons. It 
appears worthy of a trial run s that's my next project.

My goal is to have a solar powered gateway and the RPi has taken me a 
lot closer to that goal.

Ray vk2tv




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