Linux Cyberdeck Design
Thought for 41 sec
There’s still a moderate amount left before this is a full manufacturable board. The first-pass schematic is started, but we are not ready for PCB layout/manufacturing yet.
Main things still left to figure out
-
Display connection
- Exact Waveshare 6.25" DSI LCD-B connector pinout
- DSI lane count
- Backlight power/current
- Touch interface, if any
- Correct FPC connector part
-
Battery and power
- Exact 10,000 mAh battery pack
- Battery connector/current rating
- Battery protection/NTC details
- Confirm charger settings for that pack
- Validate 5 V boost converter can handle CM5 + LTE + display + USB-A peaks
-
Protection parts
- USB-C ESD protection
- USB-A USB 3.0 ESD protection
- HDMI ESD protection
- SIM card ESD protection
- Possibly battery/input fuse or protection
-
Regulator final values
- Final inductor part numbers
- Capacitor voltage/package choices
- TPS61288 compensation check
- Thermal/current margin check
- Layout-sensitive switching-node constraints
-
CM5 details
- Decide whether to add RTC backup for CM5 VBAT
- Decide whether to expose nRPIBOOT/service pads
- Confirm GPIO assignments for LTE, audio, IMU, keyboard wake
-
LTE/SIM7600 details
- Confirm exact SIM7600G-H-M.2 hardware guide handling for VDD_AUX and VDD_1V8
- Confirm LTE/GNSS antenna connector placement strategy
- Add SIM ESD
- Add RF/layout keepout rules
-
Keyboard board
- Main-board FPC is planned, but keyboard PCB itself still needs to be designed
- Need switch/keycap sourcing
- Need keyboard RP2040 schematic/firmware pin map finalized
-
Mechanical basics
- Rough board size
- Port locations
- Battery location
- Screen/keyboard placement constraints
- Mounting holes
- Antenna placement/keepouts
-
PCB layout setup
- Stackup choice, likely 6-layer because of USB 3.0, HDMI, MIPI DSI, RF, and power density
- Controlled-impedance rules
- Differential-pair rules
- Power trace/current rules
- Thermal copper areas
-
Bring-up and manufacturing prep
- Test pads
- Debug headers
- Board bring-up checklist
- BOM cleanup
- Footprint review
- DRC
- Gerbers/BOM/pick-and-place
Schematic is roughly 55–65% figured out.
Full board readiness is more like 30–40% complete, because layout, power validation, protection, display details, and mechanical constraints are still significant.
The biggest blockers are:
- Exact display connector/pinout
- Exact battery pack
- Power validation for the 5 V rail
- ESD/protection parts
- Mechanical board size/port placement
- Keyboard PCB design
Once those are decided, the remaining work becomes much more straightforward.
Power, display, protection
Find display pinout
Validate power rail
Add protection parts
Add test pads
Review battery connector
Refine this doc
Ask about this doc
Keyboard and Display Direction — Linux Cyberdeck
Status
Draft direction based on the user's latest requirements and researched module documentation.
User Direction
- Use an RK3588-class SOM carrier rather than a raw RK3588S2 + discrete LPDDR4x board.
- Battery should be a large tablet-style battery pack sized for useful runtime and enough peak power for the device.
- Replace the previous AliExpress smart-keyboard uncertainty with:
- Keyboard reference: M5Stack Unit CardKB / CardKB v1.1.
- Screen alternative: Waveshare 6.25inch DSI LCD (B).
- Consider designing a custom keyboard PCB that is slightly longer than the M5Stack CardKB.
M5Stack CardKB Reference Findings
Sources checked:
- https://docs.m5stack.com/en/unit/cardkb
- https://docs.m5stack.com/en/unit/cardkb_1.1
- M5Stack CardKB v1.1 PDF resource.
Design-relevant facts:
Table
| Item | Finding |
|---|---|
| Interface | I2C |
| I2C address | 0x5F |
| Connector | HY2.0-4P / Grove-style connector |
| Connector pinout | GND, 5V, SDA, SCL |
| Supply | 5 V |
| Current | Approx. 20 mA found in PDF resource; not consistently listed on product page |
| Controller | CardKB v1.1 page lists ATMega8A; PDF resource also references ATmega328P / MEGA328P-AU, so exact revision matters |
| Key count | Product page says 50 keys; PDF resource says 56 keys, likely revision/document mismatch |
| Size | Product page: 88.0 x 54.0 x 5.0 mm; PDF resource: 84 x 54 x 5 mm |
| Weight | About 14–17 g depending source/revision |
Custom Keyboard PCB Direction
Recommended direction: build a custom keyboard PCB inspired by CardKB but not constrained to cloning it exactly.
Proposed Electrical Architecture
Diagram
Recommended Interface Choice
- USB HID keyboard is the lowest-friction Linux interface if the keyboard connects directly to the RK3588 SOM.
- I2C keyboard is useful if the design includes an embedded controller / power-management MCU that scans keys and wakes the system.
- Best carrier-board architecture may include both:
- Keyboard MCU enumerates as USB HID for Linux input.
- A few wake/power keys also connect to an always-on controller or SOM wake GPIO.
Mechanical Direction
- Baseline CardKB reference size: roughly 84–88 mm long x 54 mm wide x 5 mm thick.
- User wants custom keyboard PCB slightly longer than CardKB.
- Proposed first mechanical target: 100–110 mm long x 54–60 mm wide, pending desired key spacing and enclosure width.
- Use real switch/keycap geometry before PCB layout. If using tactile domes, Kailh Choc, Blackberry-style keys, or small SMD tact switches, the key pitch and board thickness change significantly.
Sources checked:
- https://www.waveshare.com/product/displays/6.25inch-dsi-lcd-b.htm
- https://www.waveshare.com/wiki/6.25inch_DSI_LCD
Design-relevant facts:
Table
| Item | Finding |
|---|---|
| Product | Waveshare 6.25inch DSI LCD (B), SKU 35000 |
| Resolution | 720 x 1560 |
| Panel | IPS, optical bonding, toughened glass |
| Brightness | 500 cd/m² |
| Touch | 5-point capacitive touch |
| Touch interface | I2C; Goodix touchscreen appears as 10-0014 Goodix Capacitive TouchScreen |
| Display interface | Raspberry Pi-style MIPI DSI |
| Refresh | Up to 60 Hz through Raspberry Pi DSI |
| Power | 5 V via pogo/spring pins or PH2.0 4-pin cable depending host board |
| DSI connector | 15-pin interface definition on panel side; uses 22-pin DSI cable for Pi 5/CM5/CM4/CM3 and 15-pin FPC for Pi 4/3-style boards |
| DSI lanes | Pinout shows two data lanes plus clock: DN0/DP0, DN1/DP1, CN/CP |
| Interface pinout | 1 GND, 2 DSI1_DN1, 3 DSI1_DP1, 4 GND, 5 DSI1_CN, 6 DSI1_CP, 7 GND, 8 DSI1_DN0, 9 DSI1_DP0, 10 GND, 11 SCL0, 12 SDA0, 13 GND, 14 3V3, 15 3V3 |
| Included cables | DSI-Cable-12cm, 15-pin 1.0 mm FPC cables, PH2.0 4-pin cable |
| Software | Raspberry Pi overlay vc4-kms-dsi-waveshare-panel,6_25_inch; RK3588 support will require SOM vendor device-tree/display-driver compatibility work |
Display Integration Risk
The display is documented for Raspberry Pi DSI, not guaranteed plug-and-play on every RK3588 SOM. The SOM must expose a compatible 2-lane MIPI DSI output, I2C for touch, 3.3 V control, 5 V panel power, and Linux device-tree support for the panel/touch controller.
Revised Carrier Architecture Impact
- Select an RK3588-class SOM with documented MIPI DSI output and Linux DTS examples.
- Add a panel FPC connector or adapter footprint compatible with the Waveshare cable/pinout.
- Provide 5 V panel power with enough margin and switch/control if needed.
- Route DSI as controlled-impedance high-speed differential pairs with tight skew control and solid ground reference.
- Route I2C touch lines with correct voltage domain and pull-ups.
- Design the keyboard as a separate low-speed PCB/daughterboard or integrated lower section of the carrier, depending enclosure shape.
Open Questions Before Schematic Capture
- Should the keyboard be USB HID, I2C, or both?
- What key technology should the custom keyboard use: small tactile switches, low-profile mechanical switches, Blackberry-style keypad, or rubber-dome style?
- Desired keyboard dimensions: is 100–110 mm long acceptable, or should it be closer to the original CardKB?
- Should the keyboard be a separate replaceable daughterboard or part of the main carrier PCB?
- Which exact RK3588 SOM will be used, and does it expose MIPI DSI lanes compatible with the Waveshare screen?
- Should the 6.25inch display be portrait, landscape, or physically rotated with software rotation?
- What tablet-battery voltage/chemistry should be used: 1S, 2S, or a smart battery pack?
Status
User Direction
M5Stack CardKB Reference Findings
Custom Keyboard PCB Direction
Proposed Electrical Architecture
Recommended Interface Choice
Mechanical Direction
Waveshare 6.25inch DSI LCD (B) Findings
Display Integration Risk
Revised Carrier Architecture Impact
Open Questions Before Schematic Capture
