May 192018
 

Recently, a new project sprang up on the Hackaday.io site; it was for the KiteBoard, an open-source cellular development platform.  In a nutshell, this is a single-board-computer that embeds a full mobile system-on-chip and runs the Android operating system.  The project is seeking crowd funding for the second version of this platform.

With it, you can build smartphones (of course), tablets, tele-presence robots, or really, any project which can benefit from a beefy CPU with a built-in cellular modem.  It comes as a kit, which you then assemble yourself.  The level of difficulty in assembly is no greater than that of assembling a desktop PC: the circuit boards are pre-populated, you just need to connect them together.  In this version, some soldering of pushbuttons and wires is needed: all through-hole components.  No reflow ovens or solder paste is necessary here, an 8-year-old could do it.

The break-out board for the CPU card features in addition to connections for all the usual cellular phone signals (e.g. earpiece, microphone, button inputs) a GPIO header that follows the de-facto standard “Raspberry Pi” interface, allowing many Raspberry Pi “hats” to plug directly into this board.

That lends itself greatly to expandability.  Want a eInk or OLED notification display on the back?  A scrolling LED display?  A piano?  A games console?  Knock yourself out!  You, are the designer, you decide.  There are lots of options.

I for one, would consider an amateur radio transceiver, an external antenna socket and a beefier battery.  Presently, I get around with the ZTE T83 (“Telstra Dave”), which works okay, but as it runs an old version of Android (4.1), running newer applications on it is a problem.  I believe it could run something newer, but ZTE believe that their job was finished in 2013 when the first one rolled off the production line.

The box did not include a copy of the kernel sources or any link to where that could be obtained.  (GNU GPL v2 section 2b?  What’s that?)

The successor, the T84 is a little better, in fact it has pretty much the same hardware that’s in Kite, but it struggles in rural areas.  On a recent trip into the Snowy Mountains, my phone would be working fine, when my father’s T84 would report “no service available”.  Clearly, someone at Telstra/ZTE screwed up the firmware on it, and so it fails to switch networks correctly.  Without the sources, we are unable to fix that.  Even something as simple as replacing a battery is neigh on impossible, they’re built like bombs: not designed to be taken apart.

I have no desire to spend money on a company that puts out poorly supported rubbish running pirated operating system kernels.  The story is similar elsewhere, and most devices while better in specs and operating system, lack the external antenna connection that I desire in a phone.

Kite represents a breath of fresh air in that regard.  It is to smart phones, what the Raspberry Pi is to single board computers in general.  It’s not only designed to be taken apart, it’s shipped to you as parts.  Apparently with Kite v2, there’ll be schematics available, so you’ll be able to look-up the datasheets of respective components and be able to make informed decisions about part substitutions.  All antenna connections are socketed, so you can substitute at will.

While the OS isn’t going to be as open as one might like (mobile chipset manufacturers like their black boxes), it’s a BIG step in the right direction.  There’s more scope for supporting this platform long-term, than contemporary ones.

As far as actually using Kite, Shree Kumar was generous enough to organise the loan of a Kite for me to test with the Australian networks.  The phone takes up to two micro-SIMs (about 15mm×12mm); one on the daughter card (this is SIM 1) and one on the CPU card (SIM 2).

For the sake of testing, I figured I’d try it out with the two major networks, Telstra and Optus.  As it happens, my Telstra SIM is too big (they call it a “full-size” SIM now; I remember full-size SIMs being credit-card sized), so rather than chopping up my existing SIM or getting it transferred, I bought and activated a prepaid service.  I also bought a SIM for Optus.  I bought $10 credit for each.

As it happens, the Optus one came with data, the Telstra did not.  No big deal in this case.  The phone does have a limitation in that it will talk to one 3G/4G network and one GSM (2G) network at a time.  Given both networks I chose have abandoned 2G, that pretty much means the dual-SIM functionality on this model is severely hobbled.  That said, either SIM can operate in 3G mode, and so it’s simple enough to switch one SIM into 2G mode then activate the other in 3G/4G mode.  So far, the Kite has spent most of its time on Optus.

Evidently Vodaphone still have a 2G network… at least the Kite does see one 2G cell operated by them.  Long term, this is a problem that all dual-SIM phone chipset makers will have to deal with, a future Kite may well be able to do 3G simultaneously on both SIMs, but for me, this is not a show-stopper.

I’ve put together this review of the Kite.  It’s rare for me to be in front of a camera instead of behind it, and yes, the editing is very rough.  If there is time (there won’t be this weekend) I hope to take the phone out to a rural area and try it out with the more distant networks, but so far it seems happy enough to switch to 3G when I get home, and use 4G when I’m at work, so this I see as a promising sign.

The KickStarter is lagging behind quite a way in the funding goal, but alternate options are being considered for getting this project off-the-ground.  Here’s hoping that the project does get up, and that we get to see Kite v2 being developed and made for real, as I think the mobile phone industry really does need a viable open competitor.

Dec 252017
 

So, I’m home now for the Christmas break… and the fan in my power supply decided it would take a Christmas break itself.

The power supply was purchased brand new in June… it still works as a power supply, but with the fan seized up, it represents an overheating risk.  Unfortunately, the only real options I have are the Xantrex charger, which cooked my last batteries, or a 12V 20A linear PSU I normally use for my radio station.  20A is just a touch light-on, given the DC-DC converter draws 25A.  It’ll be fine to provide a top-up, but I wouldn’t want to use it for charging up flat batteries.

Now, I can replace the faulty fan.  However, that PSU is under warranty still, so I figure, back it goes!

In the meantime, an experiment.  What happens if I just turn the mains off and rely on the batteries?  Well, so far, so good.  Saturday afternoon, the batteries were fully charged, I unplugged the mains supply.  Battery voltage around 13.8V.

Sunday morning, battery was down to 12.1V, with about 1A coming in off the panels around 7AM (so 6A being drained from batteries by the cluster).

By 10AM, the solar panels were in full swing, and a good 15A was being pumped in, with the cluster drawing no more than 8A.  The batteries finished the day around 13.1V.

This morning, batteries were slightly lower at 11.9V.   Just checking now, I’m seeing over 16A flowing in from the panels, and the battery is at 13.2V.

I’m in the process of building some power meters based on NXP LPC810s and TI INA219Bs.  I’m at two minds what to use to poll them, whether I use a Raspberry Pi I have spare and buy a case, PSU and some sort of serial interface for it… or whether I purchase a small industrial PC for the job.

The Technologic Systems TS-7670 is one that I am considering, given they’ll work over a wide range of voltages and temperatures, they have plenty of UARTs including RS-485 and RS-232, and while they ship with an old Linux kernel, yours truly has ported both U-Boot and the mainline Linux kernel.  Yes, it’s ARMv5, but it doesn’t need to be a speed demon to capture lots of data, and they work just fine for Barangaroo where they poll Modbus (via pymodbus) and M-bus (via python-mbus).

Nov 202016
 

The Yaesu FT-897D has the de-facto standard 6-pin Mini-DIN data jack on the back to which you can plug a digital modem.  Amongst the pins it provides is a squelch status pin, and in the past I’ve tried using that to drive (via transistors) the carrier detect pin on various computer interfaces to enable the modem to detect when a signal is incoming.

The FT-897D is fussy however.  Any load at all pulling this pin down, and you get no audio.  Any load.  One really must be careful about that.

Last week when I tried the UDRC-II, I hit the same problem.  I was able to prove it was the UDRC-II by construction of a crude adapter cable that hooked up to the DB15-HD connector, converting that to Mini-DIN6: by avoiding the squelch status pin, I avoided the problem.

One possible solution was to cut the supplied Mini-DIN6 cable open, locate the offending wire and cut it.  Not a solution I relish doing.  The other was to try and fix the UDRC-II.

Discussing this on the list, it was suggested by Bryan Hoyer that I use a 4.7k pull-up resistor on the offending pin to 3.3V.  He provided a diagram that indicated where to find the needed signals to tap into.

With that information, I performed the following modification.  A 1206 4.7k resistor is tacked onto the squelch status pin, and a small wire run from there to the 3.3V pin on a spare header.

UDRC-II modification for Yaesu FT-897D

UDRC-II modification for Yaesu FT-897D

I’m at two minds whether this should be a diode instead, just in case a radio asserts +12V on this line, I don’t want +12V frying the SoC in the Raspberry Pi.  On the other hand, this is working, it isn’t “broke”.

Doing the above fixed the squelch drive issue and now I’m able to transmit and receive using the UDRC-II.  Many thanks to Bryan Hoyer for pointing this modification out.

Nov 122016
 

So, recently, the North West Digital Radio group generously donated a UDRC II radio control board in thanks for my initial work on an audio driver for the Texas Instruments TLV320AIC3204 (yes, a mouthful).

This board looks like it might support the older Pi model B I had, but I thought I’d play it safe and buy the later revision, so I bought version 3 of the Pi and the associated 7″ touch screen.  Thus, an order went to RS for a whole pile of parts, including one Raspberry Pi3 computer, a blank 8GB MicroSD card, a power supply, the touch screen kit and a case.

Fitting the UDRC

To fit the UDRC, the case will need some of the plastic cut away,  rectangular section out of the main body and a similarly sized portion out of the back cover.

Modifications to the case

Modifications to the case

When assembled, the cut-away section will allow the DB15-HD and Mini-DIN6 connectors to protrude out slightly.

Case assembled with modifications

The UDRC needs some minor modifications too for the touch screen.  Probe around, and you’ll find a source of 5V on one of the unpopulated headers.  You’ll want to solder a two-pin header to here and hook that to the LCD control board using the supplied jumper leads.  If you’ve got one, use a right-angled header, otherwise just bend a regular one like I did.

5V supply for the LCD on the UDRC

5V supply for the LCD on the UDRC

You’ll note I’ve made a note on the DB15-HD, a monitor does NOT plug in here.

From here, you should be ready to load up a SD card.  NWDR recommend the use of Compass Linux, which is a Raspbian fork configured for use with the UDRC.  I used the lite version, since it was smaller and I’m comfortable with command lines.

Configuring screen rotation

If you try to boot your freshly prepared SD card, the first thing you’ll notice is that the screen is up-side-down.  Clearly a few people didn’t communicate with each-other about which way was up on this thing.

Before you pull the SD card out, it is worth mounting the first partition on the SD card and editing config.txt on the root directory of that partition. If doing this on a Windows computer ensure your text editor respects Unix line endings! (Blame Microsoft. If you’re doing this on a Mac, Linux, BSD or other Unix-ish computer, you have nothing to worry about.)

Add the following to the end of the file (or anywhere really):

# Rotate the screen the "right way up"
lcd_rotate=2

Now save the file, unmount the SD card, and put it in the Pi before assembling the case proper.

Setting up your environment

Now, if you chose the lite option like I did, there’ll be no GUI, and the touch aspect of the touchscreen is useless.  You’ll need a USB keyboard.

Log in as pi (password raspberry), run passwd to change your password, then run sudo -s to gain a root shell.

You might choose like I did to run passwd again here to set root‘s password too.

After that, you’ll want to install some software.  Your choice of desktop environment is entirely up to you, I prefer something lightweight, and have been using FVWM for years, but there are plenty of choices in Debian as well as the usual suspects (KDE, Gnome, XFCE…).

For the display manager, I’ll choose lightdm. We also need an on-screen keyboard. I tried a couple, including matchbox-keyboard and the rather ancient xvkbd. Despite its age, I found xvkbd to be the most usable.

Once you’ve decided what you want, run apt-get install with your list of packages, making sure to include xvkbd and lightdm in your list.  Other applications I included here were network-manager-gnome, qasmixer, pasystray, stalonetray and gkrellm.

Enabling the on-screen keyboard in lightdm

Having installed lightdm and xvkbd, you can now configure lightdm to enable the accessibility options.

Open up /etc/lightdm/lightdm-gtk-greeter.conf, look for the line show-indicators and tack ;~a11y on the end.

Now down further, look for the commented out keyboard setting and change that to keyboard=xvkbd. Save and close the file, then run /etc/init.d/lightdm restart.

You should find yourself staring at the log-in screen, and lo and behold, there should be a new icon up the top-right. Tapping it should bring up a 3 line menu, the bottom of which is the on-screen keyboard.

On-screen keyboard in lightdm

On-screen keyboard in lightdm

The button marked Focus is what you hit to tell the keyboard which application is to receive the keyboard events.  Tap that, then the application you want.  To log in, tap Focus then the password field.  You should be able to tap your password in followed by either the Return button on the virtual keyboard or the Log In button on the form.

Making FVWM touch-friendly

I have a pretty old configuration that has evolved over the last 10 years using FVWM that was built around keyboard-centric operation and screen real-estate preservation.  This configuration mainly needed two changes:

  • Menus and title bar text enlarged to make the corresponding UI elements finger-friendly
  • Adjusting the size of the FVWM BarButtons to suit the 800×480 display

Rather than showing how to do it from scratch, I’ll just link to the configuration tarball which you are welcome to play with.  It uses xcalendar which isn’t in the Debian repositories any more, but is available on Gentoo mirrors and can be built from source (you’ll want to install xutils-dev for xmake), stalonetray and gkrellm are both in the standard Debian repositories.

FVWM on the Raspberry Pi

FVWM on the Raspberry Pi

Enabling the right-click

This took a bit of hunting to figure out.  There is a method that works with Debian Wheezy which allows right-clicks by way of long presses, but this broke in Jessie, and the 2016-05-23 release of Compass Linux is built on the latter.  So another solution is needed.

Philipp Merkel however, wrote a little daemon called twofing.  Once installed, doing a right click is simply a two-fingered tap on the screen, there’s support for other two-fingered gestures such as pinching and rotation as well.  It is available on Github, and I have forked this, adding some udev rules and scripts to integrate it into the Raspberry Pi.

The resulting Debian package is here.  Download the .deb, run dpkg -i on it, and then re-start the Raspberry Pi (or you can try running udevadm trigger and re-starting X).  The udev rules should create a /dev/twofingtouch symbolic link and the installed Xsession.d/Xreset.d scripts should take care of starting it with X and shutting it down afterwards.

Having done this, when you log in you should find that twofing is running, and that right clicks can be performed using a two-fingered prod.

Finishing up

Having done the configuration, you should now have a usable workhorse for numerous applications.  The UDRC shows up as a second sound card and is accessible via ALSA.  I haven’t tried it out yet, but it at least shows up in the mixer application, so the signs are there.  I’ll be looking to add LinBPQ and FreeDV into the mix yet, to round the software stack off to make this a general purpose voice/data radio station for emergency communications.

Oct 132016
 

Well, today’s mail had a surprise.  Back about 6 years ago, I was sub-contracted to Jacques Electronics to help them develop some device drivers for their video intercom system.  At the time, they were using TI’s TLV320AIC3204 and system-on-modules based on the Freescale i.MX27 SoC.

No driver existed in the ALSA tree for this particular audio CODEC, and while TI did have one available under NDA, the driver was only licensed for use with a TI OMAP SoC.  I did what just about any developer would do, grabbed the closest-looking existing ALSA SoC driver, ripped it apart and started hacking.  Thus I wound up getting to grips with the I²S infrastructure within the i.MX27 and taming the little beast that is the TLV320AIC3204, producing this patch.

As the code was a derivative work, the code was automatically going to be under the GPLv2 and thus was posted on the ALSA SoC mailing list for others to use.  This would help protect Jacques from any possible GPL infringement regarding the use of that driver.  I was able to do this as it was a clean-room implementation using only material in TI’s data sheet, thus did not contain any intellectual property of my then-employer.

About that time I recall one company using the driver in their IP camera product, the driver itself never made it into the mainline kernel.  About 6 months later, another driver for the TLV320AIC3204 and 3254 did get accepted there, I suspect this too was a clean-room implementation.

Fast forward to late August, I receive an email from Jeremy McDermond on behalf of the Northwest Digital Radio.  They had developed the Universal Digital Radio Controller board for the Raspberry Pi series of computers based around this same CODEC chip.  Interestingly, it was the ‘AIC3204 driver that I developed all that time before that proved to be the code they needed to get the chip working.  The chip in question can be seen up the top-right corner of the board.

Universal Digital Radio Controller

Timely, as there’s a push at the moment within Brisbane Area WICEN Group to investigate possible alternatives to our aging packet radio system and software stack.  These boards, essentially being radio-optimised sound cards, have been used successfully for implementing various digital modes including AX.25 packet, D-Star and could potentially do FreeDV and other digital modes.

So, looks like I’ll be chasing up a supplier for a newer Raspberry Pi board, and seeing what I can do about getting this device talking to the world.

Many thanks to the Northwest Digital Radio company for their generous donation! 🙂

Jun 182016
 

So, debugging the ATTiny24A, one big problem I’ve got is understanding what the ADC is seeing in each channel. There’s no serial output, no LCD, just a handful of LEDs and a PWM output. Not good enough.

The ICSP header though, necessarily exposes the pins needed to do SPI and I²C. Could that do? I’d need something to do the transfers with.

The programmer I’ve used to date has been a Olimex STK500v2 clone (the tiny one built into a DB25 backshell), which works well, but it has one nit: I haven’t figured out a way to do raw SPI transfers with it. It might be possible, I’m not sure.

I immediately thought of the Raspberry Pi. The other option I had close on hand was a Freetronics LeoStick. One I’d have to write programming firmware for — which may be worth doing some day. The other, I can just install from repositories. But how does one interface the two?

Adafruit have this tutorial on doing exactly that. HOWEVER, they wire the Pi straight up to the AVR. Fine if they’re both 3.3V, but trouble if the AVR is running at 5V like mine. I’d expect this to release magic smoke!

So, a level shifter is needed. I happened to have a Freetronics one laying around which gave me 4 channels, good enough. I just had to figure out what pins to use. For reasons unexplained, Adafruit seem to pick weird and wonderful pins that are not close together. Another guide, suggested using the standard SPI pins. I more or less went this route, but used GPIO channel 22 instead for reset, so I could use the one female header to connect to them all.

The connector was a spare that came with the LeoStick: they come with two 13-pin ones. I cut it with a hacksaw to give me two 3-pin headers and a 6-pin header. The 3-pin headers were glued together to give me a 2×3 pin header, and the other was soldered to the level converter. Two pins had to be swapped, annoyingly, but otherwise wiring it up was straightforward.

I just ran some off-cut CAT5e cable to the ICSP connector, keeping the lead length short so as to prevent clock skew.

The configuration file for AVRDude looks like this:

# Linux GPIO configuration for avrdude.
# Change the lines below to the GPIO pins connected to the AVR.
programmer
  id    = "pi";
  desc  = "Use the Linux sysfs interface to bitbang GPIO lines";
  type  = "linuxgpio";
  reset = 22;
  sck   = 11;
  mosi  = 10;
  miso  = 9;
;

I can flash my ATTiny24A from the Pi now with the following command:

$ sudo avrdude -p t24 -c pi …arguments…

So with that done, I should be able to use a simple Python script to read and write bytes via bit-banged SPI via the ICSP header, and implement some firmware to react via SPI.

Mar 082013
 

Just recently, I managed to kill yet another hand-held. Not deliberately, just a combination of conditions and not adapting my behaviour to suit.

I have a Yaesu VX8-DR, which I mainly use on the bicycle for APRS. It isn’t bad, the GPS could be faster, and the Bluetooth is more of a gimmick (in that it only works with some Bluetooth headsets and is intermittent at best), but my biggest nit with it, is that you can’t charge the thing while it’s turned on.

This leads me to the bad habit of just leaving a DC power lead semi-permanently plugged into the side, with the other end plugged into the 12V supply on the bicycle. You guessed it… one bad day of rain, some water got in via the DC jack and basically destroyed it.  I’m pretty sure warranty doesn’t cover that kind of abuse.

I’m not in a hurry to buy another one.  In fact, I probably won’t.  I’m too clumsy to look after an expensive one, so better just to keep the two Chinese cheapies going (Wouxun KG-UVD1P’s).  This lead me to thinking about what I specifically like in a hand-held, and what features I’d look for.

Looking around, it seems the vast majority of sets out there are evolutionary.  An extra handful of memory channels, higher power, bigger battery, ohh look Bluetooth, and this one has {insert some semi-proprietary-digital-mode here}.  Yawn!

Most of them have tiny screens which can’t show a decent amount of information at a glance.  Digital voice is a long way being usable, with about 3 or 4 proprietary or semi-proprietary competing standards.  What about D-Star you say?  Well, what about it.  Nice mode, pity about the codec.  How about P25?  Same deal.

If a digital mode is going to succeed in Amateur radio, it’ll be necessary for a home base to be able to implement it with nothing more than a desktop or laptop computer loaded with appropriate Free Software and a sound card interface.  Not a silly proprietary “DV-Dongle” or some closed-source blob that speaks gibberish no other software can understand.

As for portable use; it should be possible for a hand-microphone that implements the mode on a DSP be plugged into an existing hand-held (like the Wouxun or Yaesu sets I mentioned earlier) to make it interoperable — open standards will help keep costs down here.

Until such a mode comes along (and they’re working on it — already making excellent progress on HF, keep it up guys!) there’s no point in pouring money into a digital mode that will be a white elephant in a few years.

By far the most popular mode on VHF and UHF is plain old FM.  The mode Armstrong made.  It’s everywhere, from your cheap $100 Chinese firecracker set to the most expensive SDR, they all offer it.  Repeaters abound, and it’s available to pretty much all amateur license classes.  And it works good enough for most.

The big problem with FM, is interfacing with repeaters.  In particular, the big use case with hand-helds and repeaters, is being able to recall the settings for a repeater where ever you happen to be.  Now you can carry around a booklet with the settings written in, and punch them into your radio each time.

This works better for some than others.  On the KG-UVD1P with its horrid UI, it is a tiresome affair.  The Yaesu VX-8DR and Kenwood TH-F7E aren’t bad, once you get used to them.  It’s still fiddly and time consuming, definitely not an option while mobile.  This is where memory channels come in.

Now I realise that sets which stored more channels than you could count on one digit-challenged hand were considered a revolution about 10 years ago.  Back then the idea that you could basically control a digital counter, which would supply an address to an EEPROM that would spit out the settings to drive a PLL synthesizer and other control circuitry was truly remarkable.

Today, the EEPROM and counter have been replaced by a MCU that reads the keypad matrix and outputs to a LCD panel, but we’re still basically incrementing a counter that’s acting as an address offset into non-volatile memory.  The only change has been the number of channels.  The Kenwood set I had gave you 400.  The VX-8, gives you 1000 — which can be optionally grouped into 24 banks (by far the best system I’ve seen to date).  The Wouxun gives you a poultry 128.

The hardest thing about this is finding a given repeater in a list.  128 is more than enough if you don’t travel, or if you pre-programme the set with the appropriate channels in some logical ordering before you leave.  In there hints another factor; “logical ordering”, since there’s no way to sort the memory channels by anything other than channel number.

In this day and age, 1000 channels, linearly indexed, is a joke.  I can buy a 2GB MicroSD card from the supermarket for $10.   How much repeater data could you store on one of those?  FAT file system drivers are readily implementable in modern MCUs and a simple CSV file is not that big a deal for a MCU to parse.

It wouldn’t be difficult to build up a few indexes of byte locations to store in NVRAM, and have the CSV store frequency, call sign, a Maidenhead locator and other settings of all the repeaters in the country, then allow the user to choose one searching by frequency, by call-sign, or if the user gives their current grid square (or it derives it from a GPS), by proximity.  That would be a revolution.  The same card could also store a list of Echolink and IRLP nodes, and make a note of such nodes via RF so it can automatically suggest the nearest IRLP node, take you there, then dial whatever node for you after you announce yourself on the frequency.

I’ve seen more elaborate software written for 8-bit micros like the Apple II, the Commodore 64 and the Sinclair ZX Spectrum back in the day, so clearly not beyond today’s equally powerful AVR, PIC, MSP430 and ARM chips.  A STM32F103RE packs 64KB RAM, 512KB flash and a SDIO interface in a nice small TQFP64 package and costs less than $8.  Even for a Wouxun, that’ll maybe add no more than 20% still keeping it rather competitive with the opposition.

As for user interface?  We don’t need Android on there, although that could be nice.  A decent size resistive touch-screen with a reflective dot-matrix LCD would more than suffice.  This technology, thanks to mobile phones, is cheap enough to implement in this application.  The MCUs needed to drive them have also come down in cost greatly.

Even without the touch-screen — a LCD bigger than a matchbox would allow for text that is easily readable, menus that aren’t constrained in their presentation, and a generally nicer user experience.

SDR hand-helds will likely be the next big revolution, if they are affordable, but I feel that’ll be a way off, and for rag chew on a local repeater, I doubt SDR will be that much superior.  It certainly will push the price up though.

I suppose a start will be to try and come up with a suitable front-end device that can be bolted onto existing transceiver hardware, maybe something that drives the computer control port of a mobile rig such as the FT-857 or IC-706.

From there, it just takes one brave manufacturer to package such a device up with a suitable transceiver in a hand-held form factor to put something to market.  If they did so in a way that could keep this UI module open-source, even better.  Bonus points if there’s a bit of an interface that can take a DSP for digital modes.

Want D-Star, P25, FreeDV, Wongi?  You got it, just slot in the right module, load on the firmware into the UI module, and away you go.  Want to do something special?  Break out the text editor and compiler and start hacking.  The RF side of things can still be as it was before, so shouldn’t pose any more of a problem for regulators than a transceiver with a digital modes jack and computer control interface.

I’m not sure if anyone has worked on such a front-end.  Another option would be a cradle that takes a modern smart-phone or tablet, interfaces via USB to the set, and uses the smart-phone as the UI, also extending the phone’s battery at the same time by supplying the 5V it needs to charge.  Bonus points if it can feed the audio signal to/from the phone for digital modes and/or interfacing with BlueTooth.  A pocket APRS I-Gate and Echolink node, perhaps?  Whatever takes your fancy.

I guess the real answer here will be to come up with something and see if there’s any interest — the “throw it against the wall and see what sticks” approach.