Linux Cyberdeck Design

flux

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
  1. 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
  2. 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
  3. 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
  4. Regulator final values
    • Final inductor part numbers
    • Capacitor voltage/package choices
    • TPS61288 compensation check
    • Thermal/current margin check
    • Layout-sensitive switching-node constraints
  5. 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
  6. 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
  7. 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
  8. Mechanical basics
    • Rough board size
    • Port locations
    • Battery location
    • Screen/keyboard placement constraints
    • Mounting holes
    • Antenna placement/keepouts
  9. 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
  10. Bring-up and manufacturing prep
  • Test pads
  • Debug headers
  • Board bring-up checklist
  • BOM cleanup
  • Footprint review
  • DRC
  • Gerbers/BOM/pick-and-place
My estimate
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:
  1. Exact display connector/pinout
  2. Exact battery pack
  3. Power validation for the 5 V rail
  4. ESD/protection parts
  5. Mechanical board size/port placement
  6. 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

Waiting for input

Sign up to send

Files

Schematic

Layout

3D View

Confirmed Requirements — Linux Cyberdeck
Status
This file records the user's confirmed decisions from Confirmed Decisions.md. It supersedes conflicting earlier architecture notes.
Compute
  • Module: Raspberry Pi CM5 SC1598 / CM5108000.
  • Variant: 8 GB RAM, Lite / 0 GB eMMC, wireless.
  • Boot/storage: user-accessible side-insert push-push microSD.
  • PCIe: unpopulated test pads only; no NVMe.
  • RJ45 Ethernet: omitted.
USB-C and USB Topology
  • USB-C: PD sink / UFP only.
  • USB-C data: USB 2.0 device/gadget/rpiboot, not USB 3.0.
  • No dual-role/OTG in rev 1.
  • PD target: 9/12/15 V, up to ~45 W.
  • USB-C also serves as provisioning/service port with nRPIBOOT.
  • No USB 3.0 mux needed.

Table

CM5 PortDestination
USB 3.0 #1External USB-A 3.0 with VBUS switch/current limit + ESD
USB 3.0 #2 USB2 pairsInternal 4-port USB 2.0 hub, USB2514B class
USB 2.0 OTGUSB-C connector for device/gadget/rpiboot
Internal USB hub downstream:
  • SIM7600 modem.
  • Keyboard RP2040.
  • RP2040-LoRa.
  • Spare/service.
Battery and Power
  • Battery configuration: 1S2P pack using 2× BatterySpace PL-5467100-2C pouch cells.
  • Cell: 4250 mAh, 3.7 V, 8.5 A / 2C max discharge each, UL Listed / UN38.3.
  • Cell dimensions: 101.5 x 67.5 x 5.8 mm each.
  • Pack capacity: 8500 mAh / ~31.5 Wh nominal.
  • Usable energy estimate: ~26–27 Wh.
  • Runtime estimate: ~3.3 h at 8 W, ~2.2 h at 12 W.
  • Stack size: 101.5 x 67.5 x 11.6 mm nominal.
  • Battery bay: design ~14–15 mm for tolerance and swelling headroom.
  • Protection: Tenergy PCM P/N 32190, 6 A working / 11 ± 2 A cutoff, 10K NTC B3435.
  • Battery connector: Molex Micro-Fit 3.0, 3-pos: B+, B-, NTC.
  • Leads: >=20 AWG.
  • Board-side protection: eFuse/PTC in addition to pack PCM.
  • Charge-while-running: yes.
Power IC selections:
  • PD sink: TPS25730D.
  • Charger: BQ25792.
  • 5 V boost: TPS61288.
  • LTE rail: TPS63020 @ 3.9 V.
  • 3.3 V rail: TLV62569.
  • Fuel gauge: MAX17048.
  • Battery protection: XB8886A, pending OCP check; fallback BQ29700 + FET pair.
  • USB-A VBUS switch: TPS2553.
  • ESD options: TPD4E05U06 / USBLC6-2SC6 / TPD4E02B04.
Display
  • Display: Waveshare 6.25inch DSI LCD (B).
  • Orientation: landscape clamshell; panel is portrait-native 720 x 1560 with 90° software rotation.
  • Centered above keyboard.
  • Brightness buttons: no; brightness controlled by Fn+key consumer-control codes via QMK and /sys/class/backlight.
  • Current: official typical 5 V / 400 mA; max not published, budget 1 A.
  • Carrier replicates standard Raspberry Pi 22-pin 0.5 mm DSI pinout.
  • Use included DSI-Cable-12cm plus PH2.0 5 V lead.
  • Overlay: vc4-kms-dsi-waveshare-panel,6_25_inch targets DSI1 by default; append ,dsi0 to retarget.
  • Internal DSI + external HDMI run simultaneously; no display mux.
Keyboard
  • Keyboard is split onto a 2-layer keyboard PCB connected to the main board by FPC.
  • Size: approximately 118 x 58 mm.
  • Key field: 114 x 47.5 mm.
  • Layout: 60 keys, 5 rows x 12 columns at 9.5 mm pitch.
  • Arrangement: QWERTY + number row, Sym/Fn layers, arrows bottom-right.
  • Key type: tactile switches with keycaps.
  • Switch class: Alps SKQG / C&K PTS526 class.
  • Style: Cardputer-style.
  • Backlight: no in rev 1; reserve PWM + FET + LED footprints as stuffing option.
  • Keyboard MCU: RP2040 running QMK on keyboard PCB.
  • Interface to main board: USB HID over 4–6 pin FPC.
  • Wake sideband line retained.
  • Power button is not on keyboard.
Buttons and Debug
  • Power button: left side of base, momentary button to CM5 pin 92 PWR_BUTTON.
  • Pull low = wake from shutdown / request shutdown.
  • Hold ~5 s = forced shutdown.
  • Pinhole hard-cut via PMIC_Enable.
  • Debug: internal JST-SH UART console, nRPIBOOT button, and SWD pads for keyboard RP2040 under service hatch.
Audio
  • Speaker: mono, 8 ohm, 1 W nominal.
  • Driver class: 23–28 mm micro-speaker with sealed back volume, PUI AS02308MR class.
  • Porting: front-edge ported.
  • Loudness target: phone-like.
  • Amplifier: MAX98357A I2S class-D on CM5 I2S pins.
  • Shutdown GPIO included.
RF and Antennas
  • CM5 Wi-Fi/BT: onboard antenna.
  • CM5 antenna keepout: ground cutout min 6.5 x 11 mm, ideally >=8 x 15 mm; no metal under/around antenna.
  • CM5 fallback: on-module U.FL via dtparam=ant2.
  • LTE main: external SMA via MHF4 pigtail to rear bulkhead.
  • LTE diversity: yes, internal adhesive FPC antenna, Taoglas FXUB63 class, opposite side from main.
  • GNSS: internal passive ceramic patch, 18 x 18 mm, 25 x 25 mm if it fits; base top edge.
  • Active GNSS: no; leave unpopulated bias-tee footprint.
  • SIM: physical nano-SIM, push-push, user-accessible side slot + ESD array.
  • LoRa: HF variant 850–930 MHz; one SKU covers 868/915, region set in firmware.
  • LoRa antenna: external SMA via included IPEX adapter.
  • LoRa host interface: USB via internal hub.
  • LoRa reflashing: Linux can reflash RP2040 via BOOTSEL.
External Ports and Mechanical Placement

Table

LocationPorts / Features
Right sideUSB-C, USB-A 3.0, full-size HDMI
Left sidemicroSD, nano-SIM, power button
Rear corners2x SMA: LTE main and LoRa
Front edgeSpeaker port
  • Headphone jack: no.
  • HDMI: one CM5 output; second unrouted.
  • microSD: user-accessible side-insert push-push, adjacent to SIM.
Enclosure and Board Split
  • Device footprint: ~175 x 90 mm closed.
  • Thickness: <=32 mm closed.
  • Lid thickness: ~9 mm.
  • Base thickness: ~20 mm.
  • Weight class: ~500 g.
  • Battery location: under keyboard, front of base.
  • Main board: rear of base near hinge.
  • Cooling: aluminum bottom plate doubles as CM5 heatsink through thermal pad stack.
  • Passive cooling; reserve 5 V fan pads and vent provision as insurance.
  • Board split: two boards — 6-layer main rear board + 2-layer keyboard front board over FPC.
  • Port exits: hinge owns rear spine; data ports right; access slots left; RF to rear corners.
Optional Features
  • Status LEDs: bicolor charge + power + one user GPIO LED.
  • Charging LED: charger STAT pin.
  • Power LED: LED_nPWR.
  • User-programmable button: no.
  • RTC: ML1220 rechargeable on CM5 VBAT with charge resistor per datasheet.
  • GPIO expansion: unpopulated 1.27 mm internal header with I2C/SPI/UART, 2–3 GPIO, 3V3/5V.
  • Camera connector: no; at most unpopulated 22-pin FFC on second MIPI if routing is free.
  • IMU: yes, BMI270/LSM6DSx on I2C for auto-rotate and motion wake.
  • Haptic motor: no.
Remaining Open Items
Only non-blocking implementation details remain:
  1. Keyboard switch/keycap exact part sourcing remains TBD.
    • Layout direction is confirmed as Preonic-style 5x12 ortholinear.
    • Base layer: terminal-biased, Ctrl on home-row corner, two thumb Spaces, Sym on both thumbs.
    • Sym layer: missing ASCII clustered on the right hand.
    • Fn layer: F1–F12, brightness/volume on arrows, nav cluster.
    • Matrix/RP2040 plan and 6-pin FPC including WAKE line are captured in the Keyboard Layout file.
  2. Enclosure CAD is intentionally deferred for now.
    • Hinge, SMA bulkhead exact placement, antenna keepout volumes, and service hatch will be handled later.

  • Status

  • Compute

  • USB-C and USB Topology

  • Battery and Power

  • Display

  • Keyboard

  • Buttons and Debug

  • Audio

  • RF and Antennas

  • External Ports and Mechanical Placement

  • Enclosure and Board Split

  • Optional Features

  • Remaining Open Items