V3lectronics / SPIRIT

Smartphone based on the Raspberry Pi CM 4.

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Open source smartphone, from available components. Prioritizing user experience, performance, control, repairability, innovation and privacy. (Currently in the development phase, progress documented here and on the V Electronics YT channel). Contribution and feedback is very welcome!

Contents

  1. General Specifications
  2. Hardware And Electronics
  3. Software And Operating System
  4. DIY Build Guide
  5. Parts List
  6. Cost
  7. Ethical And Environmental Concerns
  8. Compliance And Legality
  9. Resources

image

(click to expand)

General Specifications

RAM

  • 4GB or 8GB LPDDR4

CPU

  • Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC 1.5GHz

Storage

  • 32GB eMMC

Connectivity (IO)

  • 1 x USB C 2.0
  • 2.4 GHz, 5.0 GHz WiFi IEEE 802.11 b/g/n/ac wireless
  • Bluetooth 5
  • GSM

Screen

  • 5.5" Capacitive Touch TFT Display
  • resolution: 720x1280 pixels
  • datasheet

Battery

Capacity: 2.05Ah Type: Lithium Polymer Voltage: 3.7 V Dimensions: 84.5mm x 47.5mm x 6.0mm (3.33" 1.87" 0.24")

Rationale behind the small battery capacity:

-The system is expected to be much more energy efficient (e.g. fewer background tasks), than a standard smarpthone.

-Space and supply constraints

-The emptied battery can be swapped for a fully charged one to effectively get back to 100% almost instantly.

considering using cylindrical AAAA batteries for even easier replacement and swapping, however there are some drawbacks like efficiency, and environmental concerns.

Dimensions

80mm x 148mm (±1mm)

Total estimated thickness is 11.3mm (excluding camera module lens sticking out)

Main components that contribute thickness:

Component Thickness
Chassis 1 mm
PCB 0.4 mm
Battery 6 mm
Screen 3.9 mm

Camera

SPIRIT uses the 64 MP Arducam Hawkeye camera.

Name Sensor Resolution Zoom Field Of View
Pi Hawk-eye 64MP (9152 x 6944 pixels) 10x (digital) 84 degrees

Sensor: 1/1.7" stacked CMOS image sensor, 0.8 μm pixel size Lens: f/1.8 aperture, 8 cm–∞ focal range, motorised focusing Max Resolution: 9152×6944 stills; 1080p 30 fps video

For more details see the product page

For now there is no "selfie camera" on board.

(For now there is only one camera for simplicity and cost reduction)

Hardware And Electronics

(click to expand)

Raspberry Pi Compute Module 4

"The power of Raspberry Pi 4 in a compact form factor for deeply embedded applications" (CM4 website). SPIRIT uses the 4GB RAM, 32GB eMMC version of the CM. It is possible to use a different CM4 variant (for example to increase the RAM to 8GB).

It is expected that future iterations of the design will use a different chip due to memory and IO limitations.

EDA Software

All design files are openly available through this repository.

There should be no issues with opening them with newer versions of Kicad (6 and up).

The PCB layout, schematics and other files related to the board are exported from Kicad 6.0.11+dfsg-1 (Debian adapted package that excludes any non-free components).

This way all newer versions (6 and up) can open the project. If the files where made in Kicad 8 people with say kicad 7 could not open them.

The project will probably be migrated, after Kicad 8 becomes more stable or when there will be more contributors and switching versions will become annoying. For now this doesn't matter.

Carrier PCB

Custom carrier board (motherboard) that interfaces between the CM4 and the rest of the electronics. It's function is to manage other system related tasks (such as battery charging).'

This is the only custom electronic component, however all of the design files are publicly available through this repository.

Touchscreen

Capacitive LCD Display TFT MIPI Dimensions: 5.5" (139.70mm) 1280px x 720px

Replaceable Battery

The battery is mounted such that it can be easily uninstalled for replacing or privacy reasons.

An added benefit is that the user can easily replace an empty battery for a charged one - effectively eliminating the need to wait for the phone to charge. An external battery charger can also be used for unmounted batteries.

GSM Module

Not chosen yet

GPS Module

datasheet description

"YIC31009EBGG features high sensitivity, low power and ultra small form factor. The module is powered by GOKE, which provides superior sensitivity and performance even in urban canyon and dense foliage environment. [...] Through the feature of 66-channel, the YIC31009EBGG boasts a hot start in less than 1 second. Innovative design and technology suppresses jamming sources and mitigates multipath effects, assisting excellent navigation performance."

Speakers

The speaker system consists of a pair of speakers mounted symmetrically facing upwards. The speakers are both identical and the top speaker doubles as a "phone speaker".

Biometric Module

The fingerprint scanner is located on the back of the phone and has a sensing area of 8x8mm. It is rated for 10 million finger placements and can store up to 50 templates.

False acceptance rate: 1/500k (per finger) False rejection rate: 1.4-3.5 %

Headphone Jack

This phone has a TRRS headphone jack. This way the user can decide between wireless or wired.

Microphone

Omnidirectional with a theorethical frequency range 20 Hz - 10 kHz. Sensitivity: -26dB ±3dB @ 94dB SPL. Digital output (I2S)

Buttons

The power, volume and programmable buttons are identical rectangular, tactile switches with a life expectancy of 30k cycles.

The Programmable Button's function can be customized by the user. For example, it can be used for quick launching an app, instantly dialing a saved contact, toggling sound settings (silent, vibrate, sound) etc. The list of potential use cases is very long. One of them could be enabling small children or elderly people to instantly call for example a parent, or supervisor in case of emergency. Another could be to immediately launch the camera app to quickly capture a moment.

Flashlight

1W 3V white, cool LED (SMD) datasheet. Toggling on/off can be binded to the programmable button.

Software And Operating System

Once the hardware is functional it will be time to test various operating systems as well as explore the possibility of developing one based on Debian.

List of OS to test/research.

Name Website
Ubuntu Touch https://ubuntu-touch.io/
Lineage https://lineageos.org/
Graphene https://grapheneos.org/features
Android https://www.android.com/

Additionally, The Yocto Project has been suggested (not an OS) https://www.yoctoproject.org/

*** Flashing an OS

To flash an OS to eMMC pull down the ... pin

DIY Build Guide

Link to build guide/tutorial: No build guide yet

Parts List

Click here to show

todo fix links

Amount Name Unit Price (USD) Digikey Link
1 RPi CM4 65 https://www.digikey.pl/en/products/detail/raspberry-pi/SC0686/13530938?s=N4IgjCBcoLQCxVAYygMwIYBsDOBTANCAPZQDaIAHAJwAMVA7CALoC%2BLhATGSBwGxwUYAZQDCNZiyA
1 Carrier PCB ? N/A
1 Touch screen 96,99 https://www.digikey.pl/en/products/detail/nxp-usa-inc/RK055HDMIPI4MA0/16274141
1 Main Camera 66 https://www.digikey.com/en/products/detail/sparkfun-electronics/SEN-21276/21443092
1 Battery 9,85 https://www.digikey.pl/en/products/detail/jauch-quartz/LP504783JU-PCM-2-WIRES-70MM/13540155
1 ??? BMS chip
1 21 pin FFC connector 2.76 https://www.digikey.ca/en/products/detail/hirose-electric-co-ltd/FH72-31S-0-3SHW/13553267
1 22 pin FFC connector 2,21 https://www.digikey.pl/en/products/detail/hirose-electric-co-ltd/FH12-22S-0-5SH-55/1110321
1 10 pin FFC connector 0,20 https://www.digikey.pl/en/products/detail/te-connectivity-amp-connectors/1-2328702-0/9565577
1 Flashlight LED 3,03 https://www.digikey.pl/en/products/detail/lumileds/LXML-PWC1-0100/3961144
1 35mm Jack 0.97 https://www.digikey.com/en/products/detail/same-sky-formerly-cui-devices/SJ2-3574A-SMT-TR/6619530
2 Speaker 2,53 https://www.digikey.pl/en/products/detail/cui-devices/CMR-15062S-67/9561156
1 Microphone 1,95 https://www.digikey.pl/en/products/detail/knowles/SPH0645LM4H-B/5332440
1 USB C 2.0 Connector 0,81 https://www.digikey.com/en/products/detail/gct/USB4105-GF-A/11198441
? Overvoltage protector 0,43 https://www.digikey.pl/en/products/detail/littelfuse-inc/SMBJ5-0A/285950
1 Fingerprint Card 29 https://www.digikey.pl/en/products/detail/fingerprint-cards-ab/100018754/11480144?s=N4IgjCBcpgnAHLKoDGUBmBDANgZwKYA0IA9lANogAMIAugL7EC0ATMiGpAC4BOArkVIUQAVjqMQTAGztOvAcTKRKAZhDE2DCW2Uh0ASwB2Ac3w8ADjyNdxQA
1 GPS Module 7,25 https://www.digikey.pl/en/products/detail/yic/YIC31009EBGG/16499057
1 GSM Module
1 Vibration Motor 1,71 https://www.digikey.pl/en/products/detail/pui-audio-inc/HD-EMB1205-3-SC-R/16522073
1 Small LED
1 Thermistor 0,10 https://www.digikey.pl/en/products/detail/panasonic-electronic-components/ERT-JZEG103FA/9646736
1 DAC for audio output
1 Jumper female nRPI_BOOT
1 Jumper female GND
? Header pins
? M1.6 stainless screws
? M? RPi size stainless screws
? M? Arducam size stainless screws
? M? RPi size stainless tandoffs

Cost

The total cost of the device is x (excluding shipping)

Ethical And Environmental Concerns

SPIRIT phones avoid components produced in unfair or harmful ways, as well as containing conflict minerals if possible.

Here are ethical details for each major component:

-Chassis -CM4 -Battery -Screen -Chassis -Speakers

The goal is to be 100% ethically and environmentally "clean" as soon as possible, however that is not an easy task and presents multiple enginnering challenges.

?RoHS complicance

Compliance And Legality

EU

Ecodesign Regulation 2023/1670

?EMI norms

?RoHS

?REACH

?WEEE

N America

?

S America

?

Asia

?

Africa

?

Australia

?

Resources

About

Smartphone based on the Raspberry Pi CM 4.

License:GNU General Public License v3.0