2 layers24 × 27.9 mm
Rs232IsoFEC
medo64/Rs232IsoFEC
Framework laptop expansion card exposing isolated RS-232 interface
25 parts2MIT
2 layers24 × 27.9 mm
Rs232FEC
medo64/Rs232FEC6Framework laptop expansion card exposing serial RS-232 interface
- Size
- 24 × 27.9 mm
- Copper layers
- 2
- Thickness
- 0.8 mm
- Parts
- 26
- Nets
- 28
- Pads
- 120
- Tracks, vias
- 290, 38
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 15 Apr 2022
- Updated
- 29 Sep 2025
Overview
Rs232FEC is an open-source printed circuit board by medo64, from the medo64/Rs232FEC repository on GitHub, published under the MIT licence. It is a 2-layer board of 24 × 27.9 mm with 26 parts on 28 nets, routed with 290 tracks and 38 vias.
It is built around the FT232RL, MAX232IDR(AT) and PESD12VL2BT, with the B5B-XH-AM among its other parts. Its parts include 11 capacitors, 5 resistors, 2 ICs, 2 diodes and 2 connectors. It belongs with the interfaces and adapters and computers and single-board computers boards of this library.
Main components
4
FT232RL
SSOP-28-208mil-40℃~+85℃ 3.3V~5.25V、4V~5.25V USB 2.0 USB to UART SSOP-28-208mil USB Converters ROHSFTDIUSB Converters
MAX232IDR(AT)
SOP-16SOP-16 RS232 ICs ROHSAOTERS232 ICs
PESD12VL2BT
SOT-23-55℃~+125℃ 10V 12V 17.5V 50nA 80W@8/20us 8A@8/20us 8pF、15pF ESD IEC 61000-4-2、IEC 61000-4-5、IEC 61000-4-4 SOT-23 ESD and Surge Protection (TVS/ESD) ROHSTECH PUBLICESD And Surge Protection (TVS/ESD)
B5B-XH-AM
插件,P=2.5mm-25℃~+85℃ 1 14.9mm 1x5P 2.5mm 250V 3A 5 5.75mm 5P 7mm Brass K Pin、With post PA66 Through Hole Tin UL94V-0 White XH 插件,P=2.5mm Wire To Board Connector ROHSJSTWire To Board Connector
README
README.mdRS-232 Framework Expansion Card
This Framework laptop expansion card will show up on your system as a serial device and allow for a serial RS-232 communication up to 115,200 baud rate.
RS-232 Pinout
To connect to this board, one has to use a 5-pin JST XH connector. The following table represents the pinout, pin 1 being on the left as looking into the expansion card.
| # | Ref | Description | DB9 | Sym |
|---|---|---|---|---|
| 1 | CTS | Clear-to-send | 8 | c |
| 2 | RXD | Receive data | 2 | R |
| 3 | GND | Ground connection | 5 | ⏚ |
| 4 | TXD | Transmit data | 3 | T |
| 5 | RTS | Ready-to-send | 7 | r |
As power consumption is low, wires can be almost any AWG. I would recommend using 24 AWG wire 0.25 mm² as they allow for greater compatibility with other connectors.
Supported Speeds
This board employs the FT232R as its UART chip, and consequently, it supports all the baud rates this chip can handle up to 115,200 baud which is the limit of RS-232 chip used. The table below lists the standard baud rates.
| Baud rate | Actual | Error | Divisor |
|---|---|---|---|
| 300 | 300 | 0.00% | 10000.000 |
| 600 | 600 | 0.00% | 5000.000 |
| 1,200 | 1,200 | 0.00% | 2500.000 |
| 1,800 | 1,800 | 0.00% | 1666.625 |
| 2,400 | 2,400 | 0.00% | 1250.000 |
| 4,800 | 4,800 | 0.00% | 625.000 |
| 7,200 | 7,201 | 0.01% | 416.625 |
| 9,600 | 9,600 | 0.00% | 312.500 |
| 14,400 | 14,406 | 0.04% | 208.250 |
| 19,200 | 19,200 | 0.00% | 156.250 |
| 28,800 | 28,812 | 0.04% | 104.125 |
| 38,400 | 38,400 | 0.00% | 78.125 |
| 57,600 | 57,692 | 0.16% | 52.000 |
| 115,200 | 115,385 | 0.16% | 26.000 |
You can check my blog and other projects at www.medo64.com.
Parts
26| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 1u | Medo64:C (0805) | C6, C7, C9, C9, C10 |
| 4 | 100n | Medo64:C (0805) | C2, C3, C4, C5 |
| 3 | 1K | Medo64:R (0805) | R1, R2, R3 |
| 2 | PESD12VL2BT | Medo64:D TVS 12V [PESD12VL2BT,215] (SOT23-3) | D1, D2 |
| 1 | 105444-0001 | Medo64:J USB C 3.2 Edge (24w) | J1 |
| 1 | 10K | Medo64:R (0805) | R5 |
| 1 | 10n | Medo64:C (0805) | C1 |
| 1 | 4u7 | Medo64:C (0805) | C6 |
| 1 | 5K1 | Medo64:R (0805) | R4 |
| 1 | 600R | Medo64:L (0805) | L1 |
| 1 | B5B-XH-A | Medo64:J JST XH Edge [RS232] (5w) | J2 |
| 1 | DMP3099L-13 | Medo64:Q MOSFET-P (SOT23-3) | Q1 |
| 1 | FT232RL | Medo64:U Transceiver UART [FT232R] (SSOP-28) | U1 |
| 1 | MAX232IDR | Medo64:U Transceiver RS232 [MAX232IDR] (SOIC-16) | U2 |
| 1 | RX | Medo64:DS (0805) | DS1 |
| 1 | TX | Medo64:DS (0805) | DS2 |
Questions
How big is the Rs232FEC PCB?
It measures 24 × 27.9 mm and has 2 copper layers, 0.8 mm thick.
What parts does the Rs232FEC use?
26 parts, built around the FT232RL, MAX232IDR(AT), PESD12VL2BT and B5B-XH-AM. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Rs232FEC KiCad files?
From the medo64/Rs232FEC repository on GitHub, at the commit this page was made from: the board is src/Rs232FEC.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Rs232FEC design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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