UART Expansion Card
The UART Expansion Card is a community-designed expansion card providing a USB-to-UART serial interface for any Framework laptop1. Designed by Josh Cook (jyancat) of i2cLabs, it uses a CH340C bridge IC with switchable voltage and logic levels between 3.3 V and 5 V123.
Design
The card uses the CH340C USB-to-UART bridge, selected for its simplicity and low cost12. A jumper selects between 3.3 V and 5 V logic levels, making it compatible with both modern and legacy microcontrollers13. A 6-position pin socket breaks out GND, CTS, VCC, TX, RX, and DTR3.
The card extends slightly beyond the chassis to accommodate through-hole headers for stability1. It comes assembled with a 3D-printed case in black, white, or silver3.
Specifications
| Specification | Details |
|---|---|
| Bridge IC | CH340C12 |
| Logic levels | 3.3 V / 5 V (jumper-selectable)13 |
| Breakout | GND, CTS, VCC, TX, RX, DTR (6-pin socket)3 |
| Connector | Standard 2.54 mm header socket1 |
| Case | 3D-printed (black / white / silver)3 |
| Source | jyancat/UART-Expansion-Card (GitHub)2 |
| License | CERN-OHL-S-2.02 |
| Store | i2cLabs3 |
| Price | $22 AUD3 |
Availability
The card was sold assembled and tested through i2cLabs for $22 AUD3. Josh Cook assembled an initial batch of 25 units in mid-2022 and reported positive reception from buyers1.
As of mid-2025, multiple customers report that Josh Cook (i2cLabs) has not been fulfilling orders since late 2024, despite the store remaining online and accepting payments. Cook became inactive on the Framework Community and has not responded to emails. Several customers obtained chargebacks through their banks4. The design files remain open-source on GitHub for self-manufacturing2.
Related Projects
| Project | Description |
|---|---|
| RP2040 Expansion Card | Josh Cook's RP2040-based development card |
| RS-232 Expansion Card | Medved's RS-232 serial card using MCP2221 + MAX232 |
| EC Card 2 | UART-based EC debug expansion card |
| RS-485 Expansion Card | Medved's RS-485 half-duplex card |