Open-Source USB-CAN / CAN-FD Firmware Comparison for DIY CAN Adapters

This guide compares the leading open-source USB‑CAN / CAN‑FD firmware options for DIY CAN adapters. They fall into three broad families: gs_usb, a h…

Products mentioned USBCAN-I-BC | USB-CAN Converter Module

This guide compares the leading open-source USB‑CAN / CAN‑FD firmware options for DIY CAN adapters. They fall into three broad families: gs_usb, a high-performance binary protocol; Lawicel SLCAN (ASCII), which runs on top of CDC‑VCP; and proprietary or emulation-style protocols.

Project	Protocol	CAN‑FD	Timestamps	System / Notes	Best For
CANnectivity	gs_usb	Yes (hardware FDCAN)	Hardware	Zephyr RTOS, standard Linux gs_usb driver, multi-channel, DFU	Industrial adapters, mass production, long-term maintenance
candleLight_fw	gs_usb	Yes	Hardware	Bare-Metal STM32, MIT licence, classic gs_usb reference	Low-cost single-channel adapters, rapid development
Kosmonova usb‑can‑firmware‑stm32	gs_usb	Partial	Hardware	Bare-Metal STM32, lightweight, low development activity	Learning, light gs_usb customisation
LekElectronics slcan	Lawicel SLCAN (CDC‑VCP)	No (standard SLCAN)	Host / software	STM32 HAL, requires slcand, good compatibility with legacy tools	Legacy software, low-load debugging
CANable original slcan fw	Lawicel SLCAN	No	Software	Bare-Metal, official CANable firmware	Standard SLCAN reference for CANable
FYSETC UCAN	SLCAN derivative	No	Software	Optimised for Klipper / 3D printers	Dedicated to Klipper CAN-bus printers
xjtuecho USBCAN	Proprietary protocol	No	Software	Poor compatibility with third-party tools	Education and lab use; not recommended for commercial development
pcan_cantact	PEAK PCAN emulation	Partial	Hardware	Runs on CANable, PCAN‑View compatible	Direct replacement for PEAK PCAN hardware
USBtin	Lawicel SLCAN	No	Software	Mature open hardware and firmware	Simple open SLCAN reference
umi‑eng adapter	Proprietary USB CAN‑FD	Yes	Hardware	Rust firmware, modern architecture	Experimental Rust-based CAN‑FD adapter
SuperCAN	Proprietary SuperCAN	Yes	Hardware	Dedicated new CAN‑FD protocol	Research, proprietary host stack development

Protocol Overview

gs_usb — a compact binary protocol with hardware timestamps and a standard Linux kernel driver. Well suited to industrial use, CAN‑FD and heavily loaded buses, though support in older graphical tools is limited.

Lawicel SLCAN — an ASCII protocol over CDC‑VCP with excellent legacy compatibility. Protocol overhead is higher and timestamps are generated on the host; connecting to SocketCAN on Linux requires slcand.

Emulation / proprietary — PCAN emulation and bespoke protocols target specific host software, but create closed ecosystems and are a poor fit for general-purpose adapters.

Quick Selection Guide

• • General-purpose commercial USB‑CAN‑FD adapter: CANnectivity
• • Simple single-channel gs_usb: candleLight_fw
• • Compatibility with legacy serial CAN tools: LekElectronics slcan
• • Direct replacement for PEAK PCAN: pcan_cantact
• • CAN bus for Klipper printers: FYSETC UCAN

Known Limitations

The standard Lawicel SLCAN specification has no official CAN‑FD definition; every CAN‑FD-capable SLCAN depends on non-standard extensions. Hardware timestamps depend not only on the protocol but also on the MCU's FDCAN / bxCAN peripherals and the firmware implementation.

Project Links

CANnectivity: https://github.com/CANnectivity/cannectivity
candleLight_fw: https://github.com/candle-usb/candleLight_fw
LekElectronics slcan: https://github.com/LekElectronics/slcan
FYSETC UCAN: https://github.com/FYSETC/UCAN
xjtuecho USBCAN: https://github.com/xjtuecho/USBCAN
Kosmonova usb-can-firmware-stm32: https://github.com/Kosmonova/usb-can-firmware-stm32
USBtin: https://github.com/fischl/USBtin
pcan_cantact: https://github.com/moonglow/pcan_cantact
umi-eng adapter: https://github.com/umi-eng/adapter
SuperCAN: https://github.com/jgressmann/supercan

View the product page