OURS Project - DIY Open-Source Linux Smartphone

MISSION:

I wanted to give people more options and control over their most personal device, so I created an Open-source, Upgradable, Repairable Smartphone, that is also completely free of Big Tech. It's not theirs, it's O.U.R.S.

Below are the complete hardware and software instructions to build your own OURphone. Please enjoy, upgrade, tinker, improve and evolve my original design as you see fit, and share your upgrades here. Find me on LinkedIn if you have any questions / ideas.

SPECS LIST

4G LTE internet
Call, SMS, Contacts book (contains a SIM7600 with sim card)
Quad Core 1.2GHz Broadcom BCM2837 64bit CPU
1 GB RAM
Running Raspbian - a Debian Linux OS with installable app store
Capable of running Facebook, WhatsApp, YouTube etc in browser
4 inch 480 x 800 colour touch screen
5MP colour camera
GPS (in browser)
Wifi
Bluetooth audio
1 watt onboard audio speaker
3 USB ports
"Convergent": HDMI port to plug in external monitor, USB to plug in keyboard and mouse
Screen lock switch
9cm x 16cm x 3cm

HOW IT WORKS

The Raspberry Pi provides the basic functions of a computer, now made portable by the two 3.6v batteries, down-converted to 5.1V DC. Telephony (calls and SMS) is made possibly via the Waveshare 4G HAT with a normal mobile network SIM card contained therein. The Pi communicates with the 4G HAT via ordinary AT commands. The startup.sh script runs the configuration necessary to activate a 4G mobile internet connection. The phone.py app provides a UI for dialling and calling, sending, receiving and replying to SMS, adding and removing records from a simple Address Book. The built-in microphone and speaker allow normal voice calls.

GUIDING PRINCIPLES

Low cost, off-the-shelf electronic components
Less soldering / destroying, more connecting / assembling
Share everything required to replicate
Modular, standardised parts
Browser-based PWAs are the future of installable apps

IMPROVEMENTS TO MAKE

Use a faster Raspberry Pi with more RAM
Use a capacitative touch screen, not resistive touch
A bigger screen would be nice
Eliminate audio whining / cracking (I think this is an RPi 3 problem, or audio amp needs isolation)
Use shielded cables for audio carrying wires
Add a microphone / USB audio card to enable audio on video recordings
Connect phone call audio into Bluetooth (not just device audio)
Audio jack
Make less brick-like
Customise Raspbian so the UI is more usable by finger (perhaps flash another OS)
Detect and display remaining battery life

HOW TO BUILD

Buy all the parts in parts-list.xls. Connect them based on schematic.ppt.

You can snap together a working version quite quickly with just the following (no soldering required):

Raspberry Pi
4G HAT + GSM and GPS antennas
Raspberry Pi power supply
Waveshare touchscreen
Raspberry Pi camera (optional)
Headphones with built-in mic
Some USB cables
Operational mobile phone SIM card with airtime and data

Copy the files below into the Raspberry Pi home directory:

startup.sh (auto-start script to turn on internet)
phone.py (the app that allows calls, SMS, Contacts)
location-provider.py (presents stored GPS coordinates at a URL for web-based location providers)
ringtone.wav (your phone's ringtone - replace as you wish!)
mobile-keyboard.xml (a custom keyboard based on the match keyboard software)

Follow the instructions listed in setup_commands.txt to ready the Raspberry Pi, setup internet, and get the phone.py app working.

Making the cables smaller

There are many USB and audio plugs being used in the project. These are too big to allow packaging the phone's components into the wooden phone cover (box) designed for it. To make these smaller, I used thin wire to make new cables, with custom plugs on the ends. I made the plugs by using radically stripped down versions of the male plugs, taking off extra plastic housing, grinding off unnecessary bits and even bending some parts at right angles. Then I soldered on new leads and covered it with hot glue so that they are robust enough to force into tight spaces.

To save even more space I soldered USB connections directly to the back side of the Raspberry Pi. This was the plug going to the 4G HAT.

Making the Waveshare 4G HAT smaller

This is a challenge because the 4G HAT sits in between the touch screen and the Raspberry Pi itself. It is a tight, tight squeeze. I used a combination of a Dremel tool (small rotary grinder) and miniature steel cutters to painstakingly cut off the large USB ports and the two thick metal pins. These proved useless for carrying USB data, so I couldn't use them anyway - only the micro USB port seemed to work (despite many messages to their Customer Support). Be EXTREMELY careful removing these big items because it is very easy to cause massive physical destruction by lifting a track off the PCB, and then your module (the most expensive part of the build) is dead and unusable :( Only attempt if you have a surgeon's hand.

Once these items are removed and the whole device is now slim, I hot glued the GSM and GPS antenna plugs and wires in place so they are not so fragile, and wrapped the whole thing in insulation tape.

The GSM antenna provided is too big. So I purchased a PCB GSM antenna and soldered that onto the cable instead. It works ok, but signal is never 100%, only good-ish.

The GPS antenna is also too big. So I crushed it slowly in a clamp and used a screwdriver to prise off the plastic casing. This revealed a much smaller GSM antenna chip, like a hard metal square. I soldered this onto the cable instead and replaced the whole plug system with just one little neat cable.

Laser cut the phone cover

Email the file laser-cut-cover.dxf to your nearest laser cutting facility. Use 3mm MDF board - that is what the design has been made to use. You won't be able to use a thinner board without modifying the design.

Assembly and construction

This is best described with pictures, but essentially:

Make new male plugs for the micro USB and male 3.5mm TRRS / stereo plugs.
Solder all the wires for the charger, power supply (set to 5.1V DC), power switch and screen lock switch, audio amp, volume control.
Charge the batteries up for the first time, with the power switch in OFF / charging mode.
Connect all the batteries, wires and plugs and test: internet, phone call, SMS, GPS, music playing.
Insert the 4G HAT between the touchscreen and Raspberry Pi.
Fold the camera ribbon cable over the 4G HAT and over and under the batteries - stick in place with Prestick putty.
Stick the speaker with putty over the top right-hand grill (9 holes).
Place the GPS antenna next to the top left-hand grill (9 holes).
Start glueing the case together, starting from the bottom upwards, finishing with the front cover.