USB-to-serial debug boards are commonly used for board bring-up, checking for issues when a board does not boot, or accessing the serial console in systems without networking or video output. You’d just connect GND, Tx, and Rx wires to the target board, and a USB cable to the host, before running a terminal program like Putty, Minicom, or Bootterm with the correct parameters, and you should be good to go.
That’s the theory, but sometimes Tx and Rx may be inverted, the baudrate is not advertised, and so on. So Excamera Labs decided to make the TermDriver 2, an improved USB-to-serial with a small built-in display to more easily debug those issues. It can also be used in standalone mode, showing the serial console output on the tiny screen without having to connect it to a host.
TermDriver 2 specifications:
- MCU – Raspberry Pi RP2040 dual-core Arm Cortex-M0+ MCU @ 133 MHz with 264KB SRAM
- Storage – 2MB flash (Winbond 25Q16JVSIQ)
- Display
- 240×240 color IPS display, 230 PPI
- Full ANSI terminal emulation with color support
- Real-time control signal monitoring (RTS, DTR)
- Serial
- 6-pin 2.54mm pitch header for serial connection
- Baud rates – 1200 to 2,000,000 bps
- 32 KB hardware input buffer
- Control signals (RTS/DTR)
- Zero data loss architecture
- USB – Micro USB port for host connection
- Power Supply
- 5V DC input via USB
- 350 mA @ 3.3V power output
- Dimensions – Small
The adapter runs a CircuitPython firmware that enables driver-free operation on Windows, macOS, and Linux, and supports the standard USB CDC ACM device class. The full project is open-source hardware with the firmware source code, PCB design files, and 3D printed enclosure to be released under a BSD 3-clause license when the TermDriver 2 starts shipping.
Excamera Labs also provided a comparison table against other USB-to-serial cables and boards from US companies like Sparkfun and Adafruit, which shows the TermDriver 2 is only marginally more expensive, while providing extra features like a built-in LCD, higher current, and a larger receive buffer.
What’s not mentioned is that users can also purchase USB-to-serial debug boards for $1+ and up on AliExpress, which will be quite cheaper, whatever the tariffs applied. Having said that, if the adapter’s built-in display indeed saves you time, the costs will be quickly recouped.
The TermDriver 2 also doubles as a Raspberry Pi RP2040 development board, which can be programmed with C/C++, MicroPython, CircuitPython, or any other language supported by the microcontroller. It looks especially useful for field testing, where carrying a laptop may not always be convenient. Simply connect the serial wires to the target board and a 5V power source, and you’ll see the data on the screen provided your eyes can cope with such a small display…
Excamera Labs has just launched the TermDriver 2 for $24 on Crowd Supply with a $5,400 funding goal that has already been surpassed. Shipping adds $8 to the US and $18 to the rest of the world, and deliveries are scheduled to start by November 2025. It’s not the first USB debugging tool from the company, and we previously covered their SPIDriver and I2CMini tools to monitor SPI and I2C signals.
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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There are good ideas here. If it can do baud rate detection and work standalone when connected to a UART, that can indeed be convenient during debugging sessions. We all know how frequent it is to miss some output during a board bring up session just because the cables were not connected, connected to the wrong port, the term emulator not started, etc. If it could receive from both Rx and Tx lines when not connected to the PC, it could then easily help detect inverted wires, for example by blinking the Tx symbol when receiving from Tx. Also, take a board like the Orion O6, there are multiple UARTs, one for the console, one for the initial BIOS boot, one for the embedded controller etc. It can be quite convenient to have such a device connected to output debugging messages while the PC is connected to the main console.
Lots of possibilities, I’d say, beyond what you have suggested. Repurpose the flow control lines (provide an alternate configuration) to implement two uarts. Pico can do 3 easily over usb, which can be handy (eg your example of a target board with multiple output uarts). Flash a 1 or 2 in a status line to indicate activity, provide a button to switch between them. Two more buttons to allow access to a scroll back buffer. A passthrough mode from one uart to the other with logging to the screen in ascii or hex.
An optional single or dual rs232 plugin that connects to the 6 pin header.
Micro USB.. what year is this? Have i traveled back in time? Should I go buy Apple stock?
I refuse to buy more micro usb cables.. and all the ones I’ve had have broken
Pretty much exactly what I’ve wanted and the price is fine too, but micro USB is simply an instant dealbreaker. Was this designed a decade ago?
No cts? 😽
Micro USB – brilliant