Access Reader Design
Table
| Priority | Area | Risk | Required action before schematic freeze |
|---|---|---|---|
| P0 | ESP32-S3 GPIO | Boot failures if GPIO0, GPIO3, GPIO45, GPIO46 or USB pins are loaded incorrectly | Create final GPIO allocation table with boot/default states |
| P0 | Power | 5 V and 3.3 V rails may be undersized if QR, RF, Ethernet, LEDs and both relays peak together | Complete worst-case budget and thermal check at 50 C enclosure |
| P0 | PoE | Isolation, creepage, RJ45 surge and flyback safety are not yet specified | Define PoE class, transformer, isolation boundary and layout constraints |
| P0 | RF antennas | NFC/LF/Wi-Fi/PoE coexistence can reduce read range or fail EMC | Define RF floorplan, copper keepouts, tuning networks and test pads |
| P1 | External interfaces | RS-485, Wiegand, inputs, USB, relay contacts and DC/RJ45 inputs need robust ESD/EFT/surge protection | Create per-port protection matrix and choose protection parts |
| P1 | SKU strategy | One PCB with DNP groups can cause backfeed or assembly mistakes | Create formal SKU-A/SKU-B DNP matrix and no-backfeed scheme |
| P1 | Relay outputs | Contact rating and suppression for inductive loads are underdefined | Freeze NO/NC/COM, AC/DC rating, inductive-load warning and snubber footprints |
| P1 | Memory/security | 50k credentials plus 20k events, OTA and flash encryption need partition/wear analysis | Create ESP-IDF partition plan and verify no external memory needed |
Table
| Port | Required protection or design feature |
|---|---|
| DC input | Fuse/PTC, reverse-polarity MOSFET, TVS, LC or pi EMI filter |
| PoE RJ45 | Ethernet TVS, magnetics, shield strategy, PoE front-end protection |
| RS-485 | TVS on A/B, optional CMC, selectable termination and bias, failsafe transceiver |
| Wiegand | External-voltage-tolerant open-drain drivers, TVS, series resistors |
| Relay contacts | Snubber/TVS/MOV footprints, clearance and install-manual suppression guidance |
| Opto inputs | Current limit, reverse protection, TVS/RC filter, defined voltage thresholds |
| USB service | USB ESD array, shield/ground strategy, production lock-down policy |
| Tamper/buttons | ESD and debounce/filtering |
Table
| Block | SKU-A DC + Wi-Fi | SKU-B PoE + Ethernet |
|---|---|---|
| 9-32 V DC input and TPS54360B | Populate | DNP unless dual-input option is intentionally supported |
| PoE PD, flyback, RJ45 magnetics | DNP | Populate |
| W5500 Ethernet | DNP or optional | Populate |
| ESP32 Wi-Fi/BLE | Populate and active | Populate; Wi-Fi fallback or disabled by firmware |
| 5 V common rail | From DC buck | From PoE flyback secondary |
| No-backfeed components | Required | Required |
| SKU detect strap | Required | Required |
Scope
Executive Summary
Critical Findings
ESP32-S3 GPIO Gate
Power Gate
RF and Layout Gate
PoE and Safety Gate
External Protection Matrix
SKU Matrix Required Before Schematic Freeze
Open Questions to Close
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