Soil Moisture Probe Design
Thought for 29 sec
Best manual routing order for the 14 airwires
Practical airwire-clearing sequence
Placement-aware tip
For this probe, the best order is to route by function and sensitivity, not randomly. In general, routing should prioritize net classes deliberately rather than one-by-one ad hoc; the project-modification guidance explicitly calls out routing by inferred net type and prioritization order . Since your board is a narrow sensor probe with a capacitive front end, I’d use this order:
1. Route the sensor-critical nets first
- SENSE_A
- SHIELD
These are the most sensitive nets and should get the shortest, cleanest paths with the most control over nearby copper. If you route power and digital first, you’ll box yourself in and force these onto noisier paths later.
Guidelines
- Keep SENSE_A as short and direct as possible from U1 toward the sensing structure.
- Route SHIELD to surround or guard SENSE_A only where intentional.
- Avoid vias if possible.
- Keep these nets away from SDA, SCL, 1WIRE, and any broad ground copper.
- 3V3
- GND
Once the sensitive analog path is protected, lock in the supply distribution. This keeps decoupling loops compact and avoids awkward detours later.
Guidelines
- Route J1 to U1 and U2 first.
- Make the paths to C1 and C2 very short.
- Keep return paths compact on the component half of the board.
- SDA
- SCL
These are low-speed digital nets, but they are shared bus lines and should still be kept tidy and parallel only where necessary.
Guidelines
- Route from J1 to U1, with short branches to R1 and R2.
- Keep them away from SENSE_A and SHIELD.
- Don’t snake them through the sensing-region boundary.
- 1WIRE
This is usually the easiest remaining signal once analog, power, and bus routing are settled.
Guidelines
- Route J1 to U2 with the pull-up at R3.
- Keep it compact, but it does not need the same priority as the capacitive sensing net.
Practical airwire-clearing sequence
If you want a concrete hand-routing sequence, do it in this order:
- U1 SENSE_A
- U1 SHIELD
- J1 3V3 to local supply area
- 3V3 branches to U1, U2, C1, C2, R1, R2, R3
- GND return connections for U1, U2, C1, C2
- J1 to U1 SDA
- J1 to U1 SCL
- Short pull-up branches to R1 and R2
- J1 to U2 1WIRE
- Short pull-up branch to R3
Placement-aware tip
Because placement quality strongly affects trace length and routing success, it’s good practice to keep supporting parts clustered near their ICs and connectors at the edge before routing . For your board, that means:
Rule of thumb
- Analog sensor nets first
- Power second
- Digital bus third
- Lowest-priority digital last
Make pin checklist
Suggest rerouting moves
Review DRC issues
Refine this doc
Ask about this doc
Design Notes
Current manufacturing-finalization status
- Project schematic is preserved and should not be changed.
- Existing passive footprints in the current PCB layout already resolve to
SMD_0402_1005Metricfor R1, R2, R3, C1, and C2. - Current board outline is 160 mm x 100 mm and current stackup is standard-4-layer, 1.30 mm total thickness.
- Outstanding DRC shows 14 airwire errors.
Requested physical targets
- Convert to JLCPCB standard 2-layer.
- Board thickness target: 0.8 mm.
- Define a bottom 100 mm sensing region with interdigitated traces on both copper layers, 1 mm width / 1 mm spacing, soldermask left on.
- Ground pour only on the component side, with the sensing region kept clear.
- Export Gerbers and LCSC-compatible BOM.
Tooling limitation observed
The available write tools in this project session can:
- change stackup templates,
- change global layout rules,
- resize the board,
- and place components.
The available write tools in this session do not expose direct creation/editing of custom copper trace geometry, polygons, or fills for the interdigitated sensing electrodes, and they do not expose an explicit autorouter action for resolving all existing airwires. Because of that, the sensing-region copper pattern and full routing completion may require direct manual PCB editing in the editor or an additional routing/geometry tool.
Current manufacturing-finalization status
Requested physical targets
Tooling limitation observed
