I was inspired by this Hackaday post to build my own rugged off grid extensible hardware:

https://hackaday.com/2020/10/19/simplifying-the-ruggedized-raspberry-pi-portable/

Hardware:

I bought all the parts from AliExpress – list at the bottom of this post

I used the same case as the one described above. It is pretty small, and fitting the full-size R Pi 4 was a real challenge, so I chose in the end not to use the Raspberry pi as space really matters in this small case.

I used the same case as the one described above. It is pretty small, and fitting the full-size R Pi 4 was a real challenge, so I chose in the end not to use the Raspberry pi as space really matters in this small case.

I lined the case with foil tape to help with EMP, but I would not bother with this if i built this again, it was ineffective when i tested it as a cell phone still rings when sealed inside, I feel that this is sufficient proof it’s not going to do much, but it’s done.

I stuck the headers to the case with superglue and bicarbonate of soda – this forms a very strong and hard glue, that is almost like stone and sets very rapidly.

For GPS support I purchased a cheap UBLOX 7 usb dongle, an RTL-SDR SDR Receiver for radio, and a Realtek 8188etv WIFI dongle – for extra range with its external antenna .

the plan is to program ESP32-cams for surveillance should this be needed.

I used a 7 inch capacitive touch screen, its big enough for most things without taking up too much space or drawing loads of power, they are cheap and rugged. this left space in the lid for the Radxa zero to fit alongside the screen

I found 4 x flat 5000 mAh 3.7v lipo batteries online for a good price, so i included them and a cheap charging/ discharging circuit board as it gives loads of capacity (20 000 mAh should run for ages … still testing) and allows for charge and discharge at the same time.

I got a great 4 port USB hub – that provides the power and touch to the screen, and allows for extra storage, usb to ethernet, keyboard and mouse to be attached.

For the main computing, I chose the Radxa Zero with 4Gb of memory- 64Gb onboard emmc, with a 128 GB mmc card as the base for this project

I have a Raspberry Pi 4b, but found it too big, too hot and power hungry, and I don’t plan on using the double HDMI, Ethernet, etc and found the USB’s needed extending to be of any use, as they are not in useful places anyway, and these extentions take up loads of space in the case .

the Radxa Zero is the same size as an Raspberry pi zero, and almost the same power as a Raspberry pi4 b

here is the spec –https://wiki.radxa.com/Zero

“Radxa Zero features a quad core 64-bit ARM processor, up to 4GB 32bit LPDDR4 memory, HDMI output at [email protected], Wi-Fi and BT connectivity, USB 3.0, and 40-pin GPIO header. Additionally, the power port can also be used for USB 2.0 OTG to connect more peripherals”

I chose to run the Debian image .. which is pretty awesome and quite small https://wiki.radxa.com/Zero/Debian , if you stick to the instructions, you will be fine.

The big trick with the RADXA ZERO eMMC is you need to load a driver on windows to access the onboard emmc, instructions on how to do this are on this link https://wiki.radxa.com/Zero/dev/maskrom#Enable_maskrom

Software

Navit for Offline mapping software:

https://www.navit-project.org/ with a ublox 7usb dongle for navigation, its rather a challenge to get it running well, but there are loads of articles on the web to help you figure it out.

Kiwix for serving offline Wikipedia and other useful sites

https://github.com/kiwix/kiwix-tools

you can select as many zim files as you can fit.

zim files on https://library.kiwix.org/

Chirp

to manage my programmable radios

Easy SDR

https://github.com/IgrikXD/Easy-SDR loaded for my SDR receivers



Arduino

I Install Arduino and the ESP32 libraries for programming esp32-cams for surveillance and esp32 devices as ESP-NOW gateways for meshtastic – LORA devices and other IOT devices that are out there that you can program to help you out in a crisis.

Freetak

Things I learned –

The Radxa does not have an audio output, but works perfectly fine with any Bluetooth speaker.

the single USB c port needs an extension for mouse keyboard and other peripherals

The SDR radio draws loads of power and a powered USB hub is good for if you use an SDR.

Parts list :

https://www.aliexpress.com/p/wishlist/shareReflux.html?groupId=vwAV6Cr85NtLq%2B8VUiVTbQ5C98DJ0YkvQ7%2BlLm2xI%2BE%3D