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4 layers66.8 × 150 mmCooee Big brains, the printed circuit board in 3D

Cooee Big brains

DetectiveMittens/Cooee3

An open-source phone that can operate without GSM or LTE coverage. Utilising LoRa modulation and mesh networking to enable long range "off-grid" communication

Size
66.8 × 150 mm
Copper layers
4
Thickness
1.6 mm
Parts
200
Nets
223
Pads
655
Tracks, vias
594, 105
Pours
1
Routed
Yes
KiCad
KiCad 9.0 (file 20241229)
Created
5 Jan 2026
Updated
13 Jul 2026

Overview

Cooee Big brains is an open-source printed circuit board by DetectiveMittens, from the DetectiveMittens/Cooee repository on GitHub, published under the GPL-2.0 licence. It is a 4-layer board of 66.8 × 150 mm with 200 parts on 223 nets, routed with 594 tracks and 105 vias.

It is built around the ESP32-S3-WROOM-1-N8, CP2102-GMR and M210Z, with the AMS1117-3.3, SS24 and ESDA5V3L among its other parts. Its parts include 60 diodes, 39 resistors, 12 capacitors, 8 connectors and 6 ICs. It belongs with the ESP32 boards of this library.

Main components

7

README

README.md

Cooee (A LoRa Phone)

An open-source phone that can operate without GSM or LTE coverage. Utilising LoRa modulation and mesh networking to enable long range "off-grid" communication.

Come get involved or just chat here! -> Discord Cooee_renders1

Target Utilities/Functions

At time of writing (Jan 2026) Popular LoRa mesh networks only aim to support passing of text messages for public and private chat. Cooee aims to provide more of phone the features that consumers are used to

  • Voice calls: using 'Codec2' voice can be heavily compressed into small enough packets as to be supported by ~900MHz LoRa bandwidth limitations. Due to the delay that would happen if these packets needed to be retransmitted, calls would likely only be permitted between devices that have only 1 or 0 repeaters required between them.

  • Navigation: Using the data from OpenStreetMaps https://www.openstreetmap.org/ pre-loaded onto the device SD card a GPS reciever and infered location data based on signal strength to fixed repeaters of known location, the Cooee device should be able to locate itself well enough for navigation without ever needing a mobile data connection.

  • Sending images and files: While LoRa bandwidth will likely never support sending large files (videos etc) piecemeal file transfers of compressed images (jpgs) should be possible

Cooee_renders2

Applications / Uses:

The Cooee should ideally contribute to solving the following problems

  • Distress calls for help in remote locations
  • Basic communication in areas without GSM/LTE infrastructure
  • Dissemination of natural disaster and emergency warnings
  • Marking/Logging GPS locations. Users could tag and share hazards such as landmines (UXO/ERW), fires, vehicle collisions, chemical spills or dangerous wildlife.
  • Navigation in areas without GSM/LTE infrastructure

Philosophy:

My dream for this device is that is could demonstrate my ideals for what the future of harware aught to look like. This means deliberately achieving aims in ways which are not the 'best practice', such as;

  • Keeping code simple, using the Arduino framework isntead of ESP-IDF. The idea being that this increases how many people around the world would be able to understand and modify the device firmware, helping ensure that it is kept on track with providing maximum utility to the lives of those people who own one.
  • No electronic components smaller than 805 (no micro-soldering), this allows people to hand solder in repairs and hand assembly the PCB's with minimal equipement
  • SMT components on one side of the PCB only. Again allowing for easy assembly and repair without specialized gear
  • Plastic parts moulded from post consumer waste. Many plastics today claim to be 'recycled' when really they are just 'factory seconds', they have never used and discarded. I would like the plastic components of the Cooee to be injection moulded from recycld post consumer PET bottled pulled from waterways. Many countries in SEA are flooded with drink bottles made of PET. an easily recycled thermoplastic.
  • Hardware ownership. Increasingly, modern mobile devices are not really the property of the customer who paid hundreds, sometimes thousands of dollars to 'own' it. They are not free to modify it or install custom firmware, even creating custom firmware is a task far beyond the capabilities of most. This leaves people at the mercy of whatever bloatware the manufacturers have bundled. This bundled software often; listens to you at all times, sends transcripts of your conversations to corporate servers, advertises products at you, insists on volunteering additional personal details to enable use ect. I think it's high time that the cleverst people in the world put thier efforts towards creating machines that provide all of the utility that benefits us without any of the data harvesting and advertising. Imagine how nice it would be to use a navigator which simply puts your GPS position on a locally loaded map, it doesn't start suffocating your device by chewing up huge amounts of bandwidth or report everywhere you go to a server or try to encourage spending on nearby businesses. Imagine a navigator which just helps you nagivate in the most lightweight and unobtrusive way possible. This is the philisophy I want to see applied to all the functions of the Cooee software.

Parts

200
QtyValueFootprintReferences
51SS24Diode_SMD:D_0805_2012MetricD10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23, D24, D25 +35
1010kΩCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR8, R8, R9, R10, R11, R13, R14, R19, R20, R23
5LEDCapacitor_SMD:C_0805_2012MetricD4, D4, D5, D5, D74
5SolderJumper_2_OpenJumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mmJP1, JP2, JP3, JP4, JP5
41000Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR1, R1, R17, R18
41000Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR12, R24, R25, R26
410kResistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolderR27, R28, R29, R30
422ΩResistor_SMD:R_0805_2012MetricR3, R3, R4, R4
45.1kΩResistor_SMD:R_0805_2012MetricR2, R2, R5, R5
4Conn_01x02_PinConnector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_HorizontalJ5, J8, J10, J11
4MountingHole_Pad_MPMountingHole:MountingHole_3.2mm_M3_DIN965_Pad_TopBottomH1, H2, H3, H4
3100nFCapacitor_SMD:C_0805_2012MetricC6, C8, C12
310uFCapacitor_SMD:C_0805_2012MetricC1, C10, C11
3DDiode_SMD:D_0805_2012Metric_Pad1.15x1.40mm_HandSolderD1, D2, D2
21uFCapacitor_SMD:C_0805_2012MetricC3, C7
24.7uFCapacitor_SMD:C_0805_2012MetricC5, C9
2500ΩCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR6, R6
2806ΩCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR7, R7
2AMS1117-3.3Package_TO_SOT_SMD:SOT-223-3_TabPin2U1, U1
2Conn_CoaxialConnector_Coaxial:U.FL_Molex_MCRF_73412-0110_VerticalJ2, J6
2LMittensLibrary:Membrane_Pad_Switch_3mmSWe13, SWe39
2SPACEMittensLibrary:Membrane_Pad_Switch_3mmSWe1, SWe86
2TestPointTestPoint:TestPoint_Pad_1.0x1.0mmTP7, TP14
1,MittensLibrary:Membrane_Pad_Switch_3mmSWe47
1.MittensLibrary:Membrane_Pad_Switch_3mmSWe48
10MittensLibrary:Membrane_Pad_Switch_3mmESC1
11MittensLibrary:Membrane_Pad_Switch_3mmSWe8
11042PMittensLibrary:Keystone_18650_SingleBT2
11uFCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderC4
12MittensLibrary:Membrane_Pad_Switch_3mmSWe18
122uFCapacitor_SMD:C_0805_2012MetricC2
12kΩCapacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR21
13MittensLibrary:Membrane_Pad_Switch_3mmSWe20
13.3VTestPoint:TestPoint_Pad_1.0x1.0mmTP11
1330Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR22
14MittensLibrary:Membrane_Pad_Switch_3mmSWe21
15MittensLibrary:Membrane_Pad_Switch_3mmSWe25
1503398-1892USB4105-GF-A (1):MOLEX_503398-1892J3
16MittensLibrary:Membrane_Pad_Switch_3mmSWe26
17MittensLibrary:Membrane_Pad_Switch_3mmSWe27
18MittensLibrary:Membrane_Pad_Switch_3mmSWe28
19MittensLibrary:Membrane_Pad_Switch_3mmSWe29
1AMittensLibrary:Membrane_Pad_Switch_3mmSWe33
1BMittensLibrary:Membrane_Pad_Switch_3mmSWe87
1BACKMittensLibrary:Membrane_Pad_Switch_3mmSWe17
1CMittensLibrary:Membrane_Pad_Switch_3mmSWe54
1CLCKTestPoint:TestPoint_Pad_1.0x1.0mmTP6
1CTRLMittensLibrary:Membrane_Pad_Switch_3mmSWe12
1Conn_01x48MittensLibrary:LCD_TFT_DQ_48_P0.8mmJ12
1DMittensLibrary:Membrane_Pad_Switch_3mmSWe53
1DOWNMittensLibrary:Membrane_Pad_Switch_3mmSWe2
1Display CSTestPoint:TestPoint_Pad_1.0x1.0mmTP1
1EMittensLibrary:Membrane_Pad_Switch_3mmSWe52
1ENTERMittensLibrary:Membrane_Pad_Switch_3mmSWe50
1ESDA5V3LPackage_TO_SOT_SMD:SOT-23_HandsolderingD72
1ESP32-S3-WROOM-1-N8RF_Module:ESP32-S3-WROOM-1U2
1FMittensLibrary:Membrane_Pad_Switch_3mmSWe63
1GMittensLibrary:Membrane_Pad_Switch_3mmSWe73
1HMittensLibrary:Membrane_Pad_Switch_3mmSWe5
1IMittensLibrary:Membrane_Pad_Switch_3mmSWe35
1ICS-43434USB4105-GF-A (1):MIC_ICS-43434MK2
1INTERFACE-CP2102-GMR_QFN28_USB4105-GF-A (1):QFN28G_0.5-5X5MMU6
1JMittensLibrary:Membrane_Pad_Switch_3mmSWe15
1KMittensLibrary:Membrane_Pad_Switch_3mmSWe38
1Keyboard ClockTestPoint:TestPoint_Pad_1.0x1.0mmTP13
1Keyboard DataTestPoint:TestPoint_Pad_1.0x1.0mmTP12
1MMittensLibrary:Membrane_Pad_Switch_3mmSWe16
1M210ZUSB4105-GF-A (1):M210ZU5
1MAX98357AETE_TPackage_DFN_QFN:TQFN-16-1EP_3x3mm_P0.5mm_EP1.6x1.6mmU3
1MISOTestPoint:TestPoint_Pad_1.0x1.0mmTP5
1MOSITestPoint:TestPoint_Pad_1.0x1.0mmTP4
1NMittensLibrary:Membrane_Pad_Switch_3mmSWe6
1OMittensLibrary:Membrane_Pad_Switch_3mmSWe36
1PMittensLibrary:Membrane_Pad_Switch_3mmSWe37
1ProgUSB4105-GF-A (1):SW_SPST_B3U-1000P_MovedTextSW1
1QMittensLibrary:Membrane_Pad_Switch_3mmsw_Q1
1RMittensLibrary:Membrane_Pad_Switch_3mmSWe62
1RMittensLibrary:GPS_Tile_Antenna1R31
1R1Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR16
1R2Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolderR15

The 183 most common of 200 parts.

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Questions

How big is the Cooee Big brains PCB?

It measures 66.8 × 150 mm and has 4 copper layers, 1.6 mm thick.

What parts does the Cooee Big brains use?

200 parts, built around the ESP32-S3-WROOM-1-N8, CP2102-GMR, M210Z and AMS1117-3.3. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Cooee Big brains KiCad files?

From the DetectiveMittens/Cooee repository on GitHub, at the commit this page was made from: the board is PCB (KiCAD)/BigBrains/Cooee_Big_brains.kicad_pcb and its schematic PCB (KiCAD)/BigBrains/Cooee_Big_brains.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Cooee Big brains design in my own project?

Its repository publishes it under the GPL-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).