PCB Design Discussion

Scrap the carrier board. Design a standalone PCB from scratch with the ESP32-S3-WROOM-1U module directly on the board. Use all available GPIOs directly — no I2C expanders needed. This gives us full control over pin assignments and avoids the T-Embed's pin limitations.

Use the pin mappings from the HIZMOS project which already proved this works:

Full SPI bus for CC1101 + nRF24s
Direct I2C for display + PN532
Direct GPIOs for buttons, IR, SD card

I accept the extra design effort. Proceed with standalone design.

Thought for 9 sec

flux

I’ll replace the carrier architecture completely with a standalone ESP32‑S3‑WROOM‑1U board, reusing the specified direct GPIO mapping while rebuilding power, charging, display, NFC, storage, dual Sub‑GHz, dual nRF24, IR, controls, and RF layout from first principles.

Worked for 1 min 16 sec

flux

The standalone redesign was planned, but no project mutations were completed because the account ran out of available ACUs. The existing 41-component carrier design remains unchanged.

Remaining work:

Remove the carrier/bridge architecture.
Verify ESP32-S3-WROOM-1U-N16R8 GPIO conflicts—especially GPIO35–42 used by octal memory—and finalize a direct-pin remap.
Rebuild the schematic, power/charging system, radios, display, NFC, SD, controls, and IR.
Create and route the four-layer 100 × 45 mm PCB.
Run ERC/DRC and update BOM, firmware, bring-up, and regulatory files.

Document architecture requirements

Identify carrier components

Validate GPIO pin map

Files

Schematic

Layout

Preview

Block Diagram

Standalone Architecture

Text
USB-C (USB2 + 5 V) ── ESD/CC ── BQ25896 charger/power-path ── SYS
                                              │                 │
                                         1S LiPo + BQ27220      └─ 3.3 V buck-boost ── all logic/RF

ESP32-S3-WROOM-1U-N16R8
 ├─ Native USB D-/D+
 ├─ I2C ── PN532 module connector, BQ27220, BQ25896, optional BMI270
 ├─ SPI-A ── ST7789 display connector, microSD (independent CS)
 ├─ SPI-B ── 2× nRF24L01+ sockets, 2× CC1101 module sockets (independent CS/CE/GDO)
 ├─ GPIO ── navigation buttons, boot/reset, IR RX, IR LED MOSFET, WS2812 provision
 └─ GPIO expansion/debug header

Functional Blocks and Sourcing Plan

Table

Block	Decision
ESP32-S3 core/native USB	From scratch around exact ESP32-S3-WROOM-1U-N16R8 module; pin map must be checked against Espressif datasheet before wiring.
USB-C sink + ESD	From scratch using real connector and USB2 ESD array; 5.1 kΩ Rd on CC1/CC2.
Charging/power path	BQ25896 datasheet reference implementation, charge current limited to 600 mA.
Fuel gauge	BQ27220 datasheet reference implementation with required sense path.
3.3 V rail	Buck-boost selected only after worst-case load budget.
Display	Real SPI connector for a documented ST7789 module; no I2C fiction.
NFC	I2C connector for a documented PN532 module.
Radios	Two nRF24L01+ module sockets and, absent a verified integrated CC1101 RF reference, two CC1101 module sockets with no parallel antenna connector.
Storage/UI/IR	microSD, six navigation buttons, IR receiver and MOSFET-driven high-power IR LED.

PCB Partition

USB-C/charger at one short edge; ESP32-S3-WROOM-1U U.FL cable access at an edge; display and navigation controls on the user-facing side; microSD edge accessible; 2.4 GHz sockets separated from the ESP32 antenna cable and Sub-GHz module sockets; switching power kept away from RF. Layer 2 is continuous GND, Layer 3 is power, outer layers are signals/components.

Standalone Architecture
Functional Blocks and Sourcing Plan
PCB Partition