Project Start
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Created 5 project docs
Firmware Starter — WeLift Gate Controller
Arduino/PlatformIO starter for U3 ESP32-S3-WROOM-1U-N16R8. The mapping below is grounded in the live U3 netlist; TXD0/RXD0 GPIO identities a...
Board Bring-Up Plan — WeLift Gate Controller
Use an isolated, current-limited bench source, DMM, oscilloscope with appropriate differential probing, electronic load, USB data isolator w...
FCC/CE TCF Draft and RF Integration Notes — WeLift Gate Controller
Host controller using U3 ESP32-S3-WROOM-1U-N16R8, a Wi-Fi/Bluetooth module with U.FL external-antenna interface, plus an optional plug-in LT...
Preliminary Safety Analysis and FMEA — WeLift Gate Controller
The product presents only isolated, normally-open dry contacts to command inputs of an independently certified gate operator. It does not sw...
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The schematic is complete and ERC-clean, with firmware, bring-up, compliance, safety, and manufacturing files created.
Open blockers
- PCB stackup repeatedly reverts to two layers due to a platform persistence fault, so routing cannot safely proceed.
- Cellular-area placement remains unroutable.
- Production also requires the TVS, cellular connector, fuse-inrush, mounting-hole, and relay-surge items listed in the Manufacturing Readiness Checklist.
Completed files
The stackup fault has been reported internally; routing and manufacturing export remain intentionally unfinished rather than producing an unsafe board.
Fix blockers and review
Fix PCB blockers
Replace input TVS
Verify cellular connector
Review BOM cost
Refine this doc
Ask about this doc
Design Notes — WeLift Gate Controller
Verified Power Budget (schematic completion review)
Design condition: cellular transmit burst, both relay coils energized, Wi-Fi transmit, isolated field supply loaded, indicators and conversion losses included. This is deliberately conservative; normal firmware should prevent simultaneous OPEN/CLOSE relay energization.
Table
| Load | Rail | Continuous allowance | Peak allowance |
|---|---|---|---|
| LTE-M/NB-IoT carrier interface | 5 V switched | 0.4 A | 2.0 A |
| K1 + K2 relay coils (185 mA each) | 5 V | 0 A normally | 0.37 A |
| 3.3 V rail output (ESP32-S3 + logic) | 3.3 V | 0.35 A | 0.80 A |
| 3.3 V load reflected to 5 V at 90% | 5 V equivalent | 0.257 A | 0.587 A |
| B0505S isolated converter input | 5 V | 0.03 A | 0.257 A full rated load |
| LEDs/control/allowance | 5 V equivalent | 0.03 A | 0.05 A |
| 5 V converter total | 5 V | ~0.72 A | ~3.26 A |
LM5013 is rated 3.5 A output, with a 3.7 A minimum peak-current-limit threshold. The 3.26 A simultaneous worst-case allowance fits, but margin is only about 7%. Firmware shall interlock OPEN/CLOSE relay commands, and modem carrier selection must retain the 2.0 A burst limit. A carrier requiring more than 2 A or long sustained 2 A operation requires a higher-current 5 V converter revision.
At a conservative 10.5 V rectified valley and 88% converter efficiency, 16.3 W output requires approximately 1.76 A input. The 2 A fuse is therefore electrically adequate at steady peak load but has limited hot-enclosure and reservoir-capacitor inrush margin. Prototype testing shall verify nuisance-trip behavior; a time-delay 2.5 A fuse is the preferred production correction if the source and PCB copper are qualified.
Rectified Input Envelope and Storage
- 12 VAC nominal peak after bridge is approximately 15.6 V before ripple; conservative operating valley used for budget: 10.5 V.
- 24 VAC at +10% gives 37.3 V peak before bridge loss.
- U1 LM5013 100 V rating, D5 100 V rating, C1/C2 63 V rating, and C3/C4 100 V rating cover the normal envelope with useful margin.
- C1 + C2 = 9400 uF nominal. At 1.76 A and 120 Hz, idealized ripple is about 1.56 Vpp; actual ESR, source impedance, bridge conduction angle, temperature, and capacitance tolerance require bench validation.
- C1/C2 footprints corrected to radial 18 mm electrolytics; they are not ceramic 0603 parts.
LM5013 Support Review
- FB: 316 k / 100 k gives approximately 4.99 V from the 1.2 V reference.
- RON: 100 k targets approximately 300 kHz at 5 V output per TI equation.
- Bootstrap: 2.2 nF, 50 V X7R from BST to SW, as required.
- Inductor: 22 uH, shielded, 5 A RMS / 7 A saturation design target. This satisfies TI's recommendation for high-input transients and saturation margin.
- Catch diode: 100 V, 5 A Schottky; cathode at SW and anode at GND.
- Output: 2 x 22 uF X7R, 10 V. Effective capacitance under DC bias must remain above the TI minimum.
- UVLO: 1 M / 150 k gives nominal turn-on near 11.5 V and turn-off near 10.7 V.
- PGOOD: open drain with 47 k pull-up to 3.3 V.
Cellular Path
MP5077 VIN and VCC are on 5 V, all VIN/VOUT pins are paralleled, 36 k ILIM sets approximately 2.28 A, 22 nF SS gives approximately 4 ms soft-start, and 470 uF plus 100 nF local storage is provided. EN has a 100 k hardware pull-down so MCU reset or power loss disables the modem rail.
J7 project-defined pinout:
1–2 CELL_5V_SW, 3–4 GND, 5 RX into ESP32, 6 TX from ESP32, 7 CTS into ESP32, 8 RTS from ESP32, 9 MODEM_EN, 10 MODEM_RESET_N, 11–12 intentionally unused/mechanical. The selected library entry is named BM10B but exposes 12 terminals; footprint/pin numbering must be mechanically verified before layout and modem-carrier fabrication.
MCU, USB, Relays, and Inputs
- ESP32-S3-WROOM-1U-N16R8 uses U.FL external antenna, 3.3 V local 100 nF + 10 uF, EN 10 k/1 uF, GPIO0 10 k pull-up and BOOT switch.
- Native USB uses GPIO19 D− and GPIO20 D+, 22 ohm series resistors, USBLC6-2SC6, independent 5.1 k CC pull-downs, and all connector grounds/shields bonded to board GND. USB VBUS is used only as the ESD-array reference; it does not power the board.
- Relay GPIOs feed 100 ohm gate resistors; 100 k gate pull-downs guarantee default OFF. Each coil has a Schottky flyback diode. Only COM and NO reach field terminals; NC pins are intentionally unconnected.
- Position contacts use isolated 5 V wetting power through 1.3 k resistors and VO615A optocouplers. Logic collectors have 10 k pull-ups and 10 nF filters. Field-side return is ISO_GND, intentionally separate from board GND.
Validation and Remaining Assumptions
- Electrical review after wiring reports zero ERROR/WARNING/OPEN/UNCERTAIN ERC findings.
- All active-device power pins and required support pins are connected or explicitly marked no-connect.
- Existing SMBJ33CA input TVS has 33 V standoff, too close to the 37.3 V high-line 24 VAC peak. Flux library search did not provide a verified bidirectional SMB part at >=40 V standoff and >=600 W. Replace with a qualified 40–43 V bidirectional TVS before production; current D1 is prototype-only and may conduct at high-line.
- Relay contact surge suppression cannot be finalized without the certified gate operator command-input voltage/current and cable surge target; adding a low-voltage clamp across dry contacts could violate true dry-contact behavior. Keep contacts floating and validate external surge protection at the system level.
- Exact cellular carrier is not selected. Connector pinout above is a board-defined interface, not a claim of compatibility with a specific modem.
- Outdoor surge level, enclosure, cable glands, creepage/coating process, and compliance test plan remain system-level qualification items.
Safety Boundary
The PCB only closes gate-controller command contacts. It does not switch motor conductors and must not defeat photo-eyes, edges, limits, emergency release, or the certified operator controller. CLOSE is a request to the existing controller, not a direct motor command.
Verified Power Budget (schematic completion review)
Rectified Input Envelope and Storage
LM5013 Support Review
Cellular Path
MCU, USB, Relays, and Inputs
Validation and Remaining Assumptions
Safety Boundary
