2 layers24 × 27.9 mm
2 layers24 × 27.9 mm
Rs485IsoFEC
medo64/Rs485IsoFECIsolated RS-485 Framework Expansion Card
- Size
- 24 × 27.9 mm
- Copper layers
- 2
- Thickness
- 0.8 mm
- Parts
- 28
- Nets
- 21
- Pads
- 122
- Tracks, vias
- 259, 30
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 12 Nov 2023
- Updated
- 31 Jan 2024
Overview
Rs485IsoFEC is an open-source printed circuit board by medo64, from the medo64/Rs485IsoFEC repository on GitHub, published under the MIT licence. It is a 2-layer board of 24 × 27.9 mm with 28 parts on 21 nets, routed with 259 tracks and 30 vias.
It is built around the FT232RL, B4B-XH-A and SM12T1G. Its parts include 13 capacitors, 6 resistors, 2 ICs, 2 connectors and 1 diode. It belongs with the interfaces and adapters boards of this library.
Main components
3
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
B4B-XH-A
插件,P=2.5mm,4PUncategorisedJST
SM12T1G
SOT-23100nA 12V 15A@8/20us 15V 30V 40pF、100pF 450W@8/20us Bidirectional 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)
README
README.mdIsolated RS-485 Framework Expansion Card
This Framework laptop expansion card will show up on your system as a serial device and allow for isolated RS-485 communication up to 460,800 baud rate.
Please note that this card is using automatic transmit control and 120Ω termination.
Pinout
To connect to this board, one has to use a 4-pin JST XH connector. The following table represents the pinout, pin 1 being on the left as looking into the expansion card.
| # | Ref | Description |
|---|---|---|
| 1 | GND | Ground connection |
| 2 | A | Negative (low for logic 1 and high for logic 0) |
| 3 | B | Positive (high for logic 1 and low for logic 0) |
| 4 | NC | Not connected |
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 500,000 baud which is the limit of isolator 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 |
| 230,400 | 230,769 | 0.16% | 13.000 |
| 460,800 | 461,538 | 0.16% | 6.500 |
While rates above this can be set, they are not guaranteed to work.
You can check my blog and other projects at www.medo64.com.
Parts
28| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 100n | Medo64:C (0805) | C4, C5, C6, C7, C8, C9, C10 |
| 3 | 10n | Medo64:C (0805) | C1, C2, C3 |
| 3 | 1K | Medo64:R (0805) | R2, R3, R4 |
| 2 | 10u | Medo64:C (0805) | C12, C13 |
| 1 | 105444-0001 | Medo64:P USB C 3.2 Edge (24w) | P1 |
| 1 | 10K | Medo64:R (0805) | R5 |
| 1 | 120R | Medo64:R (0805) | R1 |
| 1 | 4u7 | Medo64:C (0805) | C11 |
| 1 | 5K1 | Medo64:R (0805) | R5 |
| 1 | 600R | Medo64:L (0805) | L1 |
| 1 | ADM2682E | Medo64:U Transciever RS485 Isolated ADM2682E (SOIC-16) | U2 |
| 1 | B4B-XH-A | Medo64:J JST XH Edge [RS485] (4w) | J1 |
| 1 | DMP3099L-13 | Medo64:Q MOSFET-P (SOT23-3) | Q1 |
| 1 | FT232RL | Medo64:U Transciever UART FT232RL (SSOP-28) | U1 |
| 1 | RX | Medo64:DS (0805) | DS1 |
| 1 | SM12T1G | Medo64:D TVS SM05T1G (SOT23-3) | D1 |
| 1 | TX | Medo64:DS (0805) | DS2 |
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Questions
How big is the Rs485IsoFEC PCB?
It measures 24 × 27.9 mm and has 2 copper layers, 0.8 mm thick.
What parts does the Rs485IsoFEC use?
28 parts, built around the FT232RL, B4B-XH-A and SM12T1G. 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 Rs485IsoFEC KiCad files?
From the medo64/Rs485IsoFEC repository on GitHub, at the commit this page was made from: the board is src/Rs485IsoFEC.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Rs485IsoFEC 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).