2 layers83.3 × 65.3 mm
SimonShield
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46 parts14kMIT
2 layers66 × 75 mm
Spool sentry
rwrife/spool-sentryUSB-powered ESP32-C3 monitor for 3D-printing hobbyists to track dry-box humidity, temperature, and filament spool mass through a private local dashboard without controlling heaters or printers.
- Size
- 66 × 75 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 46
- Nets
- 40
- Pads
- 140
- Tracks, vias
- 203, 17
- Pours
- 8
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 2 Sep 2026
- Updated
- 2 Nov 2026
Overview
Spool sentry is an open-source printed circuit board by rwrife, from the rwrife/spool-sentry repository on GitHub, published under the MIT licence. It is a 2-layer board of 66 × 75 mm with 46 parts on 40 nets, routed with 203 tracks and 17 vias.
Its parts include 11 capacitors, 10 resistors, 3 ICs, 3 diodes and 3 connectors. It belongs with the home automation and IoT boards and the ESP32 and RISC-V boards of this library.
README
hardware/README.mdHardware design artifacts
This directory now carries the schematic source-of-truth for the Spool Sentry carrier board.
Included files
spool-sentry.kicad_pro/spool-sentry.kicad_sch: KiCad 9 project + schematicsym-lib-table,fp-lib-table: local library bindings used by this schematiclib/spool-sentry.kicad_sym: project-local custom symbols (XIAO ESP32-C3 module, NAU7802 ADC)lib/spool-sentry.pretty/XIAO_ESP32C3.kicad_mod: project-local XIAO module footprintlib/spool-sentry.dcm: symbol documentation metadata
What this schematic covers
- USB 5V SELV power entry and protection path (USB-C UFP + PPTC + TVS + reverse-current block)
- Controller module (
U1: Seeed XIAO ESP32-C3) - Bridge ADC path (
U2: NAU7802) and load-cell connector (J2) - Environmental sensor path (
U3: SHT40) on shared I2C - Dedicated user button (
SW1) for tare/calibration/recovery interactions - Status RGB indicator (
D3+ current-limit resistors) - Test points for safe bring-up/diagnostics
Regenerating verification artifacts
From the repository root:
# Schematic ERC (text report)
kicad-cli sch erc --format report \
--output docs/verification/kicad-erc.rpt \
hardware/spool-sentry.kicad_sch
# Netlist + BOM exports from schematic symbol properties
./scripts/export_schematic_bom.py hardware/spool-sentry.kicad_sch
# Optional external schematic analyzer outputs (JSON + text)
# (path depends on local Hermes skill checkout)
# python3 <path-to-analyze_schematic.py> hardware/spool-sentry.kicad_sch --output docs/verification/schematic-analysis.json
# python3 <path-to-analyze_schematic.py> hardware/spool-sentry.kicad_sch --output docs/verification/schematic-analysis.txt --textThe issue-specific validation summary is in
docs/verification/issue-2-hardware-schematic.md.
Parts
46| Qty | Value | Footprint | References |
|---|---|---|---|
| 10 | R_0603_1608Metric | R_0603_1608Metric | R1, R2, R3, R4, R5, R6, R7, R8, R9, R10 |
| 10 | TestPoint_Pad_D1.5mm | TestPoint_Pad_D1.5mm | TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9, TP10 |
| 9 | C_0603_1608Metric | C_0603_1608Metric | C2, C4, C5, C6, C7, C8, C9, C10, C11 |
| 4 | MountingHole_3.2mm_M3 | MountingHole_3.2mm_M3 | MH1, MH2, MH3, MH4 |
| 2 | C_1206_3216Metric | C_1206_3216Metric | C1, C3 |
| 1 | D_SMA | D_SMA | D2 |
| 1 | D_SOD-123F | D_SOD-123F | D1 |
| 1 | Fuse_1812_4532Metric | Fuse_1812_4532Metric | F1 |
| 1 | JST_GH_SM04B-GHS-TB_1x04-1MP_P1.25mm_Horizontal | JST_GH_SM04B-GHS-TB_1x04-1MP_P1.25mm_Horizontal | J2 |
| 1 | LED_Avago_PLCC6_3x2.8mm | LED_Avago_PLCC6_3x2.8mm | D3 |
| 1 | PinHeader_1x04_P2.54mm_Vertical | PinHeader_1x04_P2.54mm_Vertical | J3 |
| 1 | SOIC-16_3.9x9.9mm_P1.27mm | SOIC-16_3.9x9.9mm_P1.27mm | U2 |
| 1 | SW_SPST_PTS810 | SW_SPST_PTS810 | SW1 |
| 1 | Seeed XIAO ESP32-C3 | XIAO_ESP32C3 | U1 |
| 1 | Sensirion_DFN-4_1.5x1.5mm_P0.8mm_SHT4x_NoCentralPad | Sensirion_DFN-4_1.5x1.5mm_P0.8mm_SHT4x_NoCentralPad | U3 |
| 1 | USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal | USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal | J1 |
Questions
How big is the Spool sentry PCB?
It measures 66 × 75 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Spool sentry use?
46 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Spool sentry KiCad files?
From the rwrife/spool-sentry repository on GitHub, at the commit this page was made from: the board is hardware/spool-sentry.kicad_pcb and its schematic hardware/spool-sentry.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Spool sentry design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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