[OZAPRS] Raspbery Pi (RPi) Gateway

Wed Sep 5 11:02:55 EST 2012

Hi Ray,

Looks like you and I are on the same path.  I've taken a slightly different
route with a Beaglebone (BB) and turned it into a remotely reconfigurable
aprs digi/igate.

For a radio/modem I used the T2-301 from argent data (5-8W output).  I've
got a Toko 25W FM amplifier in the output TX chain that I can command on
and bypass as required  For remote internet one of the Tel$tra USB modems
has worked nicely with the BB USB socket.

The key to this sort of project is the kernel and what options it had
enabled, then it's just a question of compiling the tools.  The BB has the
full AX25 stack compiled in by default in the Angstrom distribution.  Was a
doddle to rebuild the tools.  I'm using aprx for the digi.

The BB is only enabled when the iGate functionality is required, otherwise
the T2-301 can implement a basic digi on it's own.   I'm currently working
on a small arduino system to control the selection of iGate, APRS digi,
amplifier etc.  It will reprogram the T2-301 (turns KISS ON and OFF etc)
and turn things on and off as required, it sort of sits there between the
BB and T2-301 and listens for aprs commands (in KISS) or DTMF commands off
the aprs channel (DTMF is my last resort short of taking a drive).  It will
also implement the battery charging and protection mechanisms.   This has
been a work in progress for some weeks, will a large number of weeks of
writing code and testing to go before finished.

I'm aiming to keep the consumption to less than 45mA (average) for a solar
powered Digi and less than 100mA for the full iGate. This means with a 24AH
battery and 65W panel the system should keep itself alive with a 99.5%
uptime, with the digi enabled approx 85-95% with same battery and solar
panel.  Stick a 80W panel and up the battery to 36Ah and I cover the BB
requirement back up over 95%.

Look forward to hearing about your experiements and results with the RPi !

73's

Matthew
VK5ZM

On Mon, Sep 3, 2012 at 1:47 PM, Ray 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 <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<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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