A Four-Layer Board for Validating Embedded Interfaces

Separate interface behavior from wiring uncertainty.

When I was debugging microcontroller communications, wiring and hardware setup could obscure whether a problem was in the peripheral, the firmware, or the test connection.

I conceived this board as a reusable test platform for CAN, SPI, I²C, and UART instead of rebuilding a different setup for each interface.

One board. Four interfaces.

The design centers on an ESP32-S3, six external connection ports, and three CAN transceivers. It uses standardized 3.3 V logic, with a 5 V input stepped down to 3.3 V, and a four-layer SIG–GND–PWR–SIG stack.

Independent design and bring-up.

I independently conceived and designed the schematic and PCB, programmed the ESP32 test peripherals, and performed the reported interface-port tests.

Practical choices for repeatable testing.

From design files to physical boards.

JLCPCB manufactured the board. I received populated/assembled and blank boards, then brought the design up and programmed the ESP32 peripherals for the test workflow.

A staged interface test workflow.

I used an STM32F413 Nucleo with a 16 MHz external oscillator and an ESP32-C6 endpoint. A laptop connected through the board’s “AIO Test” Wi-Fi interface. I tested CAN first, then exercised I²C, SPI, and UART through their respective pins and software sections.

Make access and state easier to see.

A reusable test fixture needs observability as well as interface coverage. After using the board, I added direct exposed CAN-bus access and another onboard LED.

What I’d explore next.

The board progressed from concept through design, fabrication/assembly, bring-up, power testing, and port testing. Future ideas include a smaller form factor, more oscillator flexibility, RS-232 support, and modular CANopen-oriented features.