Designing PeakNode 1 Specifications

flux

Work done
  • Confirmed and preserved the 90 mm × 60 mm board and 4-layer Signal / GND / Power / Signal stackup.
  • Reapplied baseline routing constraints for 5 mil signal, 20 mil power, 40 mil battery/charge, 0.3 mm drill, and rounded/non-90-degree trace guidance.
  • Ran routing-prep neckdown generation; kept successful neckdowns, attempted two remediation passes, and skipped the unfixable 3V3 neckdowns for U1 / IC1 / U3 so routing can proceed with normal traces there.
  • Improved placement for routeability: preserved GNSS top-left, LoRa/SMA top-right, LTE/SMA bottom-right, MCU center, and power/USB bottom-edge regions; also corrected lower-edge components back inside the board and cleared placement overlaps.
  • Re-ran checks after the routing-prep pass; the latest verified blocker state before the final placement cleanup was 6 overlapping-copper reports and 44 airwires, down from 13 overlapping-copper reports and 44 airwires at the start.
Success criteria review
  • ✅ Board size and 4-layer stackup were preserved.
  • ✅ RF/GNSS/SMA floorplan intent was preserved during cleanup.
  • ✅ Manufacturing/routing rules were reinforced as layout constraints.
  • ⚠️ Placement was improved for routeability, but final verification after the last placement cleanup could not be completed in this session.
  • ❌ Full routed-board success criteria are not met yet because there is no available board-routing action in this run to route power, RF, MCU/control, and low-speed nets in sequence.
Next steps
Proceed to the PCB routing pass in the PCB editor/autorouter: route VBUS/VBAT/3V3 first, RF paths second with no vias and 45-degree/curved bends, SPI/control buses third with length matching, then audio/UI/low-speed nets. After routing, re-run checks for airwires, copper overlaps, RF keepout infringement, power-width mismatches, and decoupling placement.

Started implementing a plan

Create an updated brief to execute the PeakNode 1 PCB routing pass on a 90×60mm 4-layer board (Top Signal / L2 GND solid / L3 3V3 Power plane / Bottom Signal), preserving RF/GNSS keepouts and SMA placements, and then run DRC to flag airwires, copper overlaps, RF keepout violations, power width violations, and missing decoupling.

What has been done so far

- Confirmed board setup: 90mm × 60mm rectangle and 4-layer stackup with L2 as Ground Plane and L3 as Power Plane.

- Applied baseline global layout rules: min trace width 0.127mm (5 mil), preferred widths 0.127mm/0.508mm/1.016mm (5/20/40 mil), hole size 0.3mm, via options noted (0.3/0.6 and 0.2/0.4 for fanout), minimum corner radius 0.25mm.

- Neckdown polygon generation attempted; persistent 3V3 neckdown collisions for U1/IC1/U3 were remediated by skipping those neckdowns after multiple attempts.

- Placement refined to preserve the intended floorplan zones (GNSS top-left, LoRa+SMA top-right, LTE+SMA bottom-right, MCU center, power+USB bottom-left/bottom edge) while reducing overlaps and improving routing channels; all components are now within the board outline.

- Latest DRC status still shows unresolved errors: overlapping copper remains (pads 68ec3f7c and b229b54f) and 44 unrouted connections (airwires).

Implementation plan

1. Re-run DRC to get current, precise overlap and airwire locations (do not rely on cached results) and identify which components/nets correspond to pads 68ec3f7c and b229b54f.

2. Clear remaining overlapping-copper errors by re-routing or adjusting local copper around the specific offending pads/nets (do not change board size or move RF connectors). Re-validate overlapping copper until zero.

3. Route power nets first (VBUS, VBAT/battery+charge path, 3V3) using width rules: 40 mil for battery/charge path, 20 mil for power distribution; prioritize short/wide paths in the power section and adequate via stitching for thermal/current return.

4. Route RF-critical traces second:

- Route LoRa RF from SX1262 matching network to LoRa SMA with no vias, no 90° bends, and maintain the CPWG geometry target; keep copper pours cleared under/around the RF feed as required.

- Route LTE RF to LTE SMA similarly with no vias and smooth bends.

- Add GND stitching via fences around RF keep-out regions at ~5mm pitch.

5. Route MCU-to-radio/control buses third:

- Route SX1262 SPI (SCK/MOSI/MISO/NSS) and control lines (BUSY/DIO1/NRESET) and ensure SPI length matching within 2mm.

- Route USB D+/D- from MCU to modem/USB-C as applicable with tight coupling and minimal stubs.

6. Route remaining audio, UI, and low-speed nets last, maintaining audio/RF isolation; ensure the NAU8810 analog ground island connection strategy is preserved.

7. Re-run full DRC and flag (and fix if possible): unconnected nets/airwires, RF keep-out violations, power trace width violations, and any new copper overlaps.

8. Run a decoupling audit: verify each IC has 100nF + 10uF where required and that caps are placed within 0.5mm of the associated power pins on the same layer; list any missing/too-far decouplers for manual correction.

Task completed.

1:00

Thought for 6 sec — Retrieving skills information
Looking up PeakNode 1 PCB routing pass RF GNSS keepouts DRC d....

flux

Created the updated routing execution brief for PeakNode 1 and saved it as PeakNode 1 PCB Routing Pass Brief. It captures the 90×60 mm 4-layer stackup, current DRC state, routing order, RF/GNSS/SMA preservation requirements, DRC checklist, and decoupling audit criteria.
M

mkommar

After routing, re-run checks for airwires, copper overlaps, RF keepout infringement, power-width mismatches, and decoupling placement

flux

I re-ran the checks: the board is not clean yet — current results show 32 airwire errors, 6 overlapping-copper errors, 1 floating-copper error, and 21 dangling-trace warnings. No specific RF-keepout or power-width violation was returned by the checked DRC set, and no decoupling error/warning was returned, but the 0.5 mm same-layer decoupling requirement still needs physical placement inspection; details are saved in Post-Routing DRC Checks.
Fix routing errors
Locate airwires
Check decoupling placement
Check power widths
Document fixes
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Schematic

Layout

3D View

Design Notes
Architecture decisions
  • MCU default: STM32U575 selected as the primary low-power Cortex-M33 MCU for strong low-power support, wide ecosystem, and easier external modem/radio integration.
  • LTE modem default: SIM7080G selected for Cat-M1/NB-IoT plus GNSS coexistence support and broad distributor availability.
  • GNSS default: u-blox M10 family selected for low-power positioning and mature ecosystem.
  • Audio path default: NAU8810 selected as the codec path for LPCNet-capable audio front end.
  • Power tree: USB-C 5V input -> protected VBUS -> BQ25628 charger / power-path -> battery / VSYS -> TPS63036 3.3V rail -> secondary 1.8V rail for IO domains where needed.
Constraints
  • Layout size: 90 mm x 60 mm
  • Stackup: 4-layer
  • IPC target: Class 2
  • Sleep current target: under 10 uA at the system level
  • RF constraints: keep-out zones under SX1262 RF region and LTE antenna region; separate noisy switching power loops from RF/GNSS sections
  • Sourcing: prefer Mouser and Digi-Key, with LCSC alternates where practical
Immediate next tasks
  • Find exact Flux library parts for MCU, charger, regulators, modem, GNSS, LoRa radio, audio codec, USB-C, battery connector, SMA connectors, LEDs, buttons, and required passives.
  • Build schematic by subsystem and wire named power and interface nets.
  • Configure board size and 4-layer stackup with conservative proto rules.

  • Architecture decisions

  • Constraints

  • Immediate next tasks