Speaking of portable CHIRP: Using the command-line chirp clone (
https://github.com/tylert/chirp.hg/ - same developers as CHIRP?) and a Raspberry Pi I put together a really simple portable CHIRP updater. I manage my CHIRP image file for my QYT-KT8900 mobile radio on my laptop and save the files to a Dropbox directory. Then, I shared that specific image file and grabbed the Dropbox share link. Next I cobbled together a small script to run on the Raspberry Pi (runs out of cron on reboot) that does a wget of the latest image file from Dropbox and runs the command-line chirp.hg - then shuts down. No soldering or GPIO work needed.
So, my workflow is: 1) make any changes I want on CHIRP on my laptop, then save the file (which gets uploaded to Dropbox). 2) Go out to my car and turn on my phone's hotspot feature. 3) Plug in the Raspberry Pi (which has a USB wifi adapter and has previously been joined to my phone's wifi) and wait for it to boot, wget the latest image and upload it to the radio (which I can see based on the radio's LEDs and reboot when done - all the while I can be headed down the road). After that I know the Raspberry Pi has been issued a shutdown command so I safely unplug it and put it back in the glovebox (I also have it email me right before shutdown so I know when a new email pops up on my phone it is safe to unplug it).
I just got a $10 Raspberry Pi Zero W - so my "portable" updater will get even smaller and have wifi built in. Future ideas would be to add some buttons for different radios (like my Baofeng HT I keep in the car) and maybe "re-update" button or a manual shutdown button. A person could really go crazy with a OLED/LCD screen and buttons to select various images (maybe for different geographical regions or different scenarios - FRS/GPRS channels included/excluded, etc.). You could also get a USB hub (or use a Raspberry Pi 2 or 3 with multiple USB ports) and have it update multiple radios in one pass.
I'm hoping to get a blog post up about it soon with more detail (although I need to setup a blog, first).
-Tycen K7TYC