Electrical Characteristics
The UEXT connector presents power and three serial buses: Asynchronous, I2C, SPI. All pins conform to 3.3 volt digital logic. The asynchronous serial bus requires additional level-shifting circuits and connectors to support RS-232, RS-422, RS-485, DMX512, MIDI.
| Pin | Name | I/O | Logic | Primary Use |
|---|---|---|---|---|
| 1 | 3.3V | S | S | +3.3 volt |
| 2 | GND | S | S | Ground |
| 3 | TXD | O | PP | Transmit Data for Async Serial bus |
| 4 | RXD | I | PP | Receive Data for Async Serial bus |
| 5 | SCL | O | OD | Clock for I2C bus |
| 6 | SDA | I/O | OD | Bidirectional Serial Data for I2C bus |
| 7 | MISO | I | PP | Serial Data In for SPI bus |
| 8 | MOSI | O | PP | Serial Data Out for SPI bus |
| 9 | SCK | O | PP | Clock for SPI bus |
| 10 | SSEL | O | PP | Slave Select for SPI bus |
Notes:
- Direction is relative to host board. I = Input, O = Output.
- S = Power Supply, PP = Push-Pull logic, OD = Open-Drain logic, all pins conform to 3.3 volt digital logic
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