| Pin | SPP Signal | Direction | Reg + Bit | Register | Bit | HW Inverted |
|---|---|---|---|---|---|---|
| 15 | Error | in | 1.3 | Base + 1 | 3 | |
| 13 | Select | in | 1.4 | Base + 1 | 4 | |
| 12 | PaperOut | in | 1.5 | Base + 1 | 5 | |
| 10 | Ack | in | 1.6 | Base + 1 | 6 | |
| 11 | Busy | in | 1.7 | Base + 1 | 7 | Yes |
| 1 | Strobe | in/out | 2.0 | Base + 2 | 0 | Yes |
| 14 | Auto-Linefeed | in/out | 2.1 | Base + 2 | 1 | Yes |
| 16 | Initialize | in/out | 2.2 | Base + 2 | 2 | |
| 17 | Select-Printer | in/out | 2.3 | Base + 2 | 3 | Yes |
| 2 | Data 0 | in/out | 0.0 | Base | 0 | |
| 3 | Data 1 | in/out | 0.1 | Base | 1 | |
| 4 | Data 2 | in/out | 0.2 | Base | 2 | |
| 5 | Data 3 | in/out | 0.3 | Base | 3 | |
| 6 | Data 4 | in/out | 0.4 | Base | 4 | |
| 7 | Data 5 | in/out | 0.5 | Base | 5 | |
| 8 | Data 6 | in/out | 0.6 | Base | 6 | |
| 9 | Data 7 | in/out | 0.7 | Base | 7 | |
| 18 - 25 | Ground |
Bidirectional control lines
Pins 1, 14, 16 and 17 are Open Collector, so they need a pull-up resistor to work, between 5K and 10K ohm is recommended.
Interrupt
Pin 10 triggers an interrupt on the rising edge. The interrupt feature needs to be enabled.
Power
Always aim at drawing the least possible currents, but 5-10mA is possible.