A Fully Programmable Industrial Networking Multi-Tool
The FalCAN Probe is a fully programmable USB multi-tool that handles CAN, RS-485, and RS-422 without the limits of basic adapter boards.
On the weekends, hobbyists make use of communications protocols such as Wi-Fi, Bluetooth, and UART to get their electronics talking to each other. But when Monday rolls around, more reliable technologies may be needed — especially in industrial settings. There, more robust protocols such as CAN and RS-422/485 are used to link equipment together. While these methods are known to be reliable when used over long distances in environments with lots of electrical noise, they are generally more difficult to work with.
Adapters that use a fixed-function bridge chip are most commonly used to interface these communications lines with a computer. This setup provides the user with a way to interact with the connected equipment, but only in a very rigid way that is limited by the capabilities of the bridge chip. Using a custom protocol timing, for instance, would be out of the question if the adapter’s hardware does not support it.
The FalCAN Probe was designed to be a multi-tool for interfacing with and debugging industrial networks. It is not limited by a fixed-function bridge chip. Instead, it is fully programmable, allowing users to modify anything and everything. You can think of the FalCAN Probe as something more like a development board than an adapter.
The device was designed around an STM32F042C6Tx Arm Cortex-M0 microcontroller running at 48 MHz. Unlike conventional USB-to-bus adapters that rely on dedicated bridge ICs, the FalCAN Probe exposes the MCU directly, giving users access to native USB functionality, GPIOs, USART pins, SWD debugging, and boot configuration headers. This means the board can serve as far more than a simple CAN or RS-485 interface.
The board supports three of the most frequently used industrial communications standards. CAN connectivity is handled by a Texas Instruments SN65HVD230 transceiver, while two SP3485EN chips provide RS-485 and full-duplex RS-422 support. A USB Type-C connection links the device to a host computer, and onboard power regulation is supplied through a MIC5504-3.3 LDO regulator. The board itself is built on a four-layer FR4 PCB with controlled impedance routing and solid ground planes.
At startup, the state of a jumper determines how the board enumerates over USB. If the jumper is open during reset, the device appears as a GS_USB CAN adapter compatible with the Linux gs_usb kernel driver. If the jumper is closed, the board enumerates as a USB CDC serial device connected to USART1 for RS-422 or RS-485 operation. After boot, the jumpers can be reconfigured freely without affecting operation.
The firmware is based on a fork of the popular candleLight firmware, but with additional support for RS-485 and RS-422 features. Because it uses the standard gs_usb interface, Linux systems such as Ubuntu and Raspberry Pi OS can work with the device using common can-utils packages without requiring custom drivers.
Since the STM32 microcontroller is fully programmable and exposes SWD pins, the board could theoretically become a custom USB instrument, CAN traffic generator, protocol analyzer, or a CMSIS-DAP or ST-Link-style programmer with the appropriate firmware.
All hardware design files, including KiCad schematics, PCB layouts, and Gerbers have been released as open source under a CC BY-SA 4.0 license. The FalCAN Probe is currently available for purchase for about $39.
R&D, creativity, and building the next big thing you never knew you wanted are my specialties.