Tag Archives: freetak

Off grid, Hackable mobile computer.


Shout out to the original build done here https://developer.run/50

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 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, 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 and too much effort to remove now .

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

Got a bunch of ESP32-CAM modules – set up with Arduino like this article: https://www.youtube.com/watch?v=36p9To2hfak

and flashed them to join the access point hosted on the internal WIFI

so easy to setup ..

nmcli dev wifi hotspot ifname wlan0 ssid whatever password "something"

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

3.7V 5000mAh 6060100 Polymer Lithium LiPo Rechargeable

RTL-SDR SDR Receiver RTL Blog V3 R820T2 RTL2832

Mini USB Hub Extensions 5Gbps 4 Ports USB Splitter

Radxa Zero SBC

Ribbon FPV HDMI-Compatible Connector Flexible

Hot-sale Tablet Case Cover Keyboard General Wired 

Up & Down & Left & Right Angled 90 Degree USB Micro

228x182x46mm Waterproof Plastic Tool box Shockproof

1024×600 Ultra HD Display 7 Inch TFT LCD Touch Screen

Future Build notes

The Radxa Zero also comes with an extendable WIFI plug “U.FL (UMCC) to RP-SMA” that can be mounted outside , so I bought one of those, this will help with the need for the rtl8188etv module that really sucks for driver support … and solves any issues with range

I might consider a Radxa Zero2 – but I don’t have much need for the additional features at this stage , also finding stock has been hard

the keyboard is nice, cause its wired, but a simple and cheaper bluetooth Keyboard and trackpad combo would probably make it into the next build, They are just WAY less stress … and I already have one in my workshop, and have used it way more than the one shown in the pictures.

I found a good charging board -will be upgrading my current one

I wont foil line the next case — no real need

the screen is great and ill be keeping it as is .. higher res would be nice .. but wasted on a screen that size and it is low power and can be switched off which is more important to me. one with a dimmer would be better .

an upgraded usb hub would be nice .. especially if it has ethernet, its hardly ever used in most applications but its good as backup