UART Framework Expansion Card
This Framework laptop expansion card will show up on your system as a serial device and allow for a non-isolated serial UART communication up to 3 Mbaud baud rate.
Please note that this card is not using RS-232 but TTL (either 3.3V or 5V) voltage levels (depending on solder-jumper position).
UART Pinout
To connect to this board, one has to use a 3-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 | RXD | Receive (TTL: 5V or 3.3V) |
| 2 | GND | Ground connection |
| 3 | TXD | Transmit (TTL: 5V or 3.3V) |
As power consumption is way below 10 mA, 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. 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 |
| 921,600 | 923,077 | 0.16% | 3.250 |
| 1,000,000 | 1,000,000 | 0.00% | 3.000 |
While chip does support baud rates up to 3 Mbaud, granularity of such rates is severely limited.
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