CAN Bridge Schematic

flux

Ок, продолжаю именно с блокеров производства: перечитаю актуальные DRC, затем сначала уберу dangling/floating copper, после этого добью оставшиеся airwires вокруг TCAN/U8 без повторного полного разбрасывания платы.

flux

Я продолжил исправления, но производственный экспорт всё ещё блокирую: DRC не чистый, значит отдавать в производство нельзя.
Что сделал:
  • Убрал большую часть dangling/stale routing artifacts.
  • Проверил и откатил небезопасный TCAN pad-stretch workaround — он создавал шорты.
  • Подтвердил, что главный блокер не в placement/routing, а в TCAN4550 footprint / exposed-pad model.
  • Обновил отчёт: Manufacturing Readiness Review.
Открытые блокеры:
  • ~18 airwires.
  • 3 floating copper.
  • 1 dangling trace warning.
  • Основная причина: TCAN4550 exposed pad / GND / OSC2 / WAKE footprint connectivity.
Следующий правильный шаг: заменить/пересобрать footprint TCAN4550RGYTQ1 по TI RGY land pattern, потом заново дороутить affected TCAN/GND зоны и только после DRC=0 экспортировать Gerber/BOM/PnP.
Fix footprint and export
Rebuild TCAN footprint
Check TI land pattern
Clean remaining DRC
Try alternate part
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Project Specification — ESP32 CAN-FD Bridge
Project Overview
Status: Draft schematic in progress.
Inline automotive CAN-FD bridge that inserts into up to three cut CAN-FD buses. In active mode, an ESP32-S3 controls six TCAN4550-Q1 CAN-FD controller/transceiver ICs and can forward or modify selected frames. In unpowered or fault mode, relay bypass reconnects each original bus.
Intended Use
Prototype / validation build for controlled vehicle-network development. Not approved for safety-critical road use without independent automotive safety, cybersecurity, EMC, and functional-safety validation.
What the Device Should Do
  • Bridge up to three split CAN-FD buses.
  • Pass messages in both directions by default.
  • Allow firmware to modify selected messages before forwarding.
  • Provide BLE phone control and BLE OTA update capability.
  • Default to direct CAN bypass when unpowered.
  • Provide USB-C programming and serial log access.
Main Features
  • ESP32-S3-WROOM-1-N16R8 module with BLE and native USB.
  • Six TCAN4550-Q1 CAN-FD controller/transceivers over two ESP32 SPI buses.
  • One 40 MHz oscillator distributed to TCAN4550 CLKIN pins through a clock buffer.
  • Per-bus relay bypass assembly. Implementation note: using two DPDT signal relays per bus to emulate 4-pole changeover behavior, because a single DPDT relay cannot both remove bypass and cleanly connect both split sides to two transceivers.
  • Protected 12 V automotive input, 5 V buck rail, and 3.3 V logic rail.
  • Two status LEDs, BOOT and RESET buttons.
System Architecture
Diagram



  
    
  
  
    
  


























14-pin automotive connector
12 V protection
5 V buck
3.3 V LDO
ESP32-S3 module
USB-C programming
SPI bus A
SPI bus B
40 MHz oscillator
Clock fanout
6x TCAN4550-Q1
3x bypass relay assemblies
Hardware Subsystems
Power
12 V vehicle input enters through a fuse/PTC, reverse-polarity protection, and load-dump TVS. A TI LMR33630-Q1 buck generates 5 V. A TI TPS7B8633-Q1 LDO generates 3.3 V.
Compute / Wireless
ESP32-S3-WROOM-1-N16R8 provides BLE, OTA support, application firmware, relay control, SPI control, and USB Serial/JTAG.
CAN-FD Interfaces
Six TCAN4550-Q1 devices are arranged as three vehicle-side/device-side pairs. Each IC has independent chip-select and interrupt. CAN line protection is included per external port.
Bypass / Failsafe
Bypass defaults closed when relay coils are unpowered. Relay coils are intended to energize only after firmware initializes and is healthy. Hardware watchdog/supervisor is recommended before production.
Interfaces and Connections
  • Connector J1: pin 1 +12 V, pin 2 GND, pins 3–14 are CAN_H/CAN_L in/out for buses 1–3.
  • USB-C: USB2 D+/D− to ESP32-S3 native USB, CC1/CC2 sink pulldowns.
  • SPI bus A: three TCAN4550 devices.
  • SPI bus B: three TCAN4550 devices.
  • GPIO: relay enables, TCAN interrupts, chip selects, BOOT, RESET, LEDs.
Power Tree and Power Budget

Table

RailLoadsEstimated TypicalEstimated Peak
5 V6x TCAN4550 VSUP, 3 relay bypass assemblies~300–450 mA~700–1000 mA
3.3 VESP32-S3, 6x TCAN4550 VIO, oscillator, clock buffer, LEDs~200–350 mA~500–700 mA
12 V inputReflected buck input current~250 mA~600 mA+
Open verification: final relay coil current and ESP32 radio duty cycle must be confirmed from selected parts and firmware behavior.
Manufacturing and Assembly Expectations
  • 4-layer PCB.
  • Compact SMD design with automotive-grade preferred parts where available.
  • CAN pairs routed as tight differential pairs with short stubs.
  • ESP32 antenna at board edge with keepout on all copper layers.
Firmware-Relevant Hardware Requirements
  • ESP32-S3 boot button on GPIO0 and reset on EN/CHIP_PU.
  • Native USB programming via USB-C.
  • Unique CS and INT pins per TCAN4550.
  • Relay enables default off during boot/reset.
  • Watchdog/supervisor recommended for relay enable gating.
Physical Design Expectations
  • Connector and CAN protection near board edge.
  • CAN relay assemblies and TCAN pairs near connector.
  • Buck converter input loop compact and isolated from ESP32 antenna.
  • 4-layer stackup with solid ground reference plane.
Important Design Decisions
  • Use frame-level CAN gateway architecture, not bit-level transparent repeater.
  • Use two DPDT relays per bus instead of one DPDT to avoid long CAN stubs in bypass/active transitions.
  • Add switchable/configurable termination footprints per split CAN segment during layout/schematic refinement.
  • Use clock fanout buffer rather than direct star fanout from oscillator to six TCAN4550 CLKIN pins.
Assumptions
  • CAN-FD data rate and bridge latency target are TBD.
  • USB should not energize relays or backfeed the vehicle power rail when vehicle 12 V is absent.
  • Automotive validation is required before any road-going safety-critical deployment.
Change Notes
  • Initial project specification created from user requirements.
  • Safety review added relay pole-count, watchdog, switchable termination, and transient-protection cautions.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Hardware Subsystems

  • Power

  • Compute / Wireless

  • CAN-FD Interfaces

  • Bypass / Failsafe

  • Interfaces and Connections

  • Power Tree and Power Budget

  • Manufacturing and Assembly Expectations

  • Firmware-Relevant Hardware Requirements

  • Physical Design Expectations

  • Important Design Decisions

  • Assumptions

  • Change Notes

ESP32 CAN-FD Bridge

ESP32 CAN-FD Bridge thumbnail
Inline automotive CAN-FD bridge with ESP32-S3 BLE control, six TCAN4550-Q1 interfaces, fail-safe relay bypass, protected 12V input, USB-C programming, and 4-layer PCB target.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$35.26–$49.26

Digi-Key

$8.82

HQonline

$5.44–$5.51

LCSC

$42.37–$43.72

Mouser

$72.75

TME

$11.39–$13.13

Verical

$10.26–$20.69

Controls