Because the previous full-board placement oscillated, I’m going to use deterministic moves for the main crowded blocks first, then run the placement agent only to clean passives around those anchors.
Worked
flux
77 days ago
The anchor move separated the big zones and fixed some previous placement problems, but many passives now need cleanup around those anchors. I’m handing only the overlap cleanup to the placement engine and allowing small passives on the bottom.
Worked
flux
77 days ago
The cleanup pass still could not converge; the overlap set is oscillating. I’m doing one final broader fresh placement with looser grouping priorities: first objective is simply no physical overlaps and all parts inside the board, still with no routing.
I have rearrange the the board this is the finaly position of the cm4, mosiac and 4g modem - correct the io board mounting holes to match the offical io board hole locations as they are currently incorrect, also add/correct the fixings and mounts and holes for the m.2, cm4 and mpcie units to suit the quectel em05 and the mosiac, here are the data sheets.
I’ll preserve your manually placed CM4/Mosaic/4G positions, then correct only mechanical items: official CM4 IO mounting holes, CM4 mounting/fixing holes, and M.2/mPCIe standoff holes from the provided datasheets. I’ll source/inspect the official geometry before mutating holes.
Status: Draft / requirements captured from uploaded redesign brief, with provisional architecture assumptions applied for Phase 1.
Design an industrial-grade Raspberry Pi Compute Module carrier board for an RTK base station. The board replaces a Teltonika router, UPS, GNSS controller, and interface boards with one commercially manufactured PCB intended for 24/7 operation and JLCPCB assembly.
Primary compute target is Raspberry Pi Compute Module 4 with a design direction that preserves future compatibility with Raspberry Pi Compute Module 5 where practical.
Intended Use
Commercial or production-intent RTK base station controller.
24/7 unattended operation.
Remote access and management over Ethernet or LTE using Linux and WireGuard.
Industrial enclosure expected; exact enclosure, mounting hole pattern, and connector exposure are not yet specified.
Design priority order from brief: reliability, manufacturability, component availability, robustness, thermal performance, serviceability, cost.
What the Device Should Do
Run Linux on a Raspberry Pi Compute Module.
Manage an RTK GNSS receiver and LTE modem simultaneously over USB 2.0.
Prefer Ethernet as the primary network path.
Automatically fail over to LTE when Ethernet fails.
Independent reset line controlled by Compute Module.
Clean, high-peak-current LTE power branch required.
LTE main and diversity RF connector paths need 50 ohm controlled impedance.
Ethernet
Gigabit Ethernet for primary WAN/LAN access.
Ethernet magnetics, connector, PoE extraction path, surge/ESD protection, common-mode filtering, and chassis-ground strategy must be selected from datasheets/reference designs.
Controlled impedance and continuous return path are required.
Use industrial-temperature variants where available.
Avoid obsolete or NRND parts.
Minimum 4 layers; 6 layers recommended if needed for impedance, return paths, EMI, or density.
Continuous ground plane required.
Controlled impedance USB, Ethernet, and RF routing required.
Provide test points for rails, reset lines, key buses, charger telemetry, and power-good signals.
Firmware-Relevant Hardware Requirements
Linux dashboard must read battery and charger/fuel-gauge status.
Compute Module GPIOs required for:
Mosaic reset.
LTE reset.
Watchdog heartbeat.
Optional load-switch enables.
Charger/fuel-gauge I2C or SMBus.
Power-source/status interrupts.
Safe shutdown and reboot controls.
GPIO table required before schematic lock.
The web dashboard software is out of PCB scope but hardware must expose signals needed to implement it reliably.
Physical Design Expectations
Board size, enclosure, mounting holes, connector edge placement, cable exit direction, antenna bulkhead style, and thermal constraints are not yet specified.
Provisional PCB stackup: 6 layers to support USB 2.0, Gigabit Ethernet, RF, PoE, LTE transients, multiple rails, and continuous return paths.
Provisional RF connector strategy: SMA or bulkhead-pigtail external antenna approach until enclosure constraints are specified.
Keep switching regulators away from GNSS and LTE RF paths.
Use thermal vias and copper areas for power components.
RF connectors should be placed to minimise trace length and avoid noisy power sections.
CM module placement must consider connector access, thermal management, and high-speed routing.
Important Design Decisions
Use USB hub rather than USB muxing so Mosaic and LTE are connected simultaneously.
Keep Mosaic and LTE on separate clean power branches.
Provide reset control immediately and include optional load-switch / hard power-cycle footprints for LTE and Mosaic in Rev A.
Design around BQ25750 charger / power-path, but verify the exact reference design and required external components before schematic wiring.
Treat Rev A as CM4-first, with CM5 compatibility tracked in a matrix rather than promised as drop-in support until connector, mechanical, power, and interface differences are checked.
Treat a dedicated fuel gauge as mandatory for battery percentage, current, and runtime dashboard functions.
Do not declare manufacturing-ready until every major subsystem has been checked against manufacturer datasheets, application notes, reference designs, and layout guidance.
Assumptions
External DC input voltage range is TBD.
Exact PoE PD module or controller is TBD.
Exact Ansmann battery pack part number and capacity are TBD.
Runtime target is TBD.
Enclosure, board outline, and mounting are TBD.
Whether fuel gauge is mandatory or optional needs confirmation.
Whether the internal USB service port is mandatory or optional needs confirmation.
Whether the existing FLX/Gerbers should be used as mechanical reference only, or as a source for any schematic reuse, needs confirmation.
CM4/CM5 Compatibility Matrix - Draft Requirements
Table
Area
Requirement
Essential interfaces
Use interfaces common to CM4 and CM5 wherever practical
Power input
Verify CM5 current and power sequencing before final regulator selection
Connectors/mechanical
Verify CM4 and CM5 connector and mounting compatibility before layout
USB
Preserve simultaneous USB paths via hub
Ethernet
Use a path compatible with both Compute Module generations
GPIO
Avoid relying on pins that change role or availability between CM4 and CM5
Datasheet and Reference Checks Required
Raspberry Pi CM4 IO board and CM4 datasheets.
Raspberry Pi CM5 mechanical/electrical documentation once available/selected.
USB2514Bi datasheet and reference schematic.
TI BQ25750 datasheet, EVM, and charger design calculator/reference design.
Selected PoE+ PD module/controller datasheet.
ArduSimple simpleRTK3B and Septentrio Mosaic-X5 interface documentation.
Quectel EM05 hardware design guide.
M.2 B-key and Mini PCIe connector datasheets/mechanical drawings.
Nano SIM socket datasheet and SIM ESD layout guidance.
Ethernet magnetics/connector datasheet and PoE/surge protection guidance.
RF connector datasheets and 50 ohm layout requirements.
Open Decisions Blocking Schematic Lock
External DC input voltage range and connector style.
Exact 2S2P Ansmann battery pack part number, capacity, connector, and NTC wiring.
Runtime target on battery.
Exact PoE+ PD module/controller preference.
Fuel gauge mandatory vs optional, and preferred gauge family.
Internal USB service port mandatory vs optional.
Board outline, enclosure, mounting hole pattern, and connector placement requirements.
Antenna connector type and enclosure antenna strategy.
Desired level of CM5 compatibility: connector/mechanical drop-in, electrical reservation only, or future spin.
Whether the uploaded existing FLX/Gerbers are a mechanical reference or only background context.
Change Notes
2026-07-20: Initial Project Specification created from uploaded complete redesign brief and pasted project overview.
2026-07-20: Applied provisional decisions to proceed with Phase 1: 9-36V DC assumption, integrated PoE+ module preference, CM4-first/CM5-matrix strategy, mandatory fuel gauge, LTE/Mosaic load-switch footprints, internal service USB provision, SMA/bulkhead antenna default, and 6-layer provisional stackup.