4-Wire-Interfaced, 2.5V to 5.5V, 28-Port I/O Expander
| Pin | Name | Type |
|---|---|---|
| 34 | ~{CS} | input |
| 32 | SCLK | input |
| 33 | DIN | input |
| 40 | DOUT | output |
| 36 | ISET | input |
| 11 | NC | passive |
| 20 | NC | passive |
| 31 | NC | passive |
| 35 | V+ | power_in |
| 37 | GND | power_in |
| 38 | GND | power_in |
| 39 | GND | power_in |
| 41 | EP | power_in |
| 30 | P4 | bidirectional |
| 28 | P5 | bidirectional |
| 26 | P6 | bidirectional |
| 24 | P7 | bidirectional |
| 1 | P8 | bidirectional |
| 3 | P9 | bidirectional |
| 5 | P10 | bidirectional |
| 7 | P11 | bidirectional |
| 2 | P12 | bidirectional |
| 4 | P13 | bidirectional |
| 6 | P14 | bidirectional |
| 8 | P15 | bidirectional |
| 9 | P16 | bidirectional |
| 10 | P17 | bidirectional |
| 12 | P18 | bidirectional |
| 13 | P19 | bidirectional |
| 14 | P20 | bidirectional |
| 15 | P21 | bidirectional |
| 16 | P22 | bidirectional |
| 17 | P23 | bidirectional |
| 18 | P24 | bidirectional |
| 19 | P25 | bidirectional |
| 21 | P26 | bidirectional |
| 22 | P27 | bidirectional |
| 23 | P28 | bidirectional |
| 25 | P29 | bidirectional |
| 27 | P30 | bidirectional |
| 29 | P31 | bidirectional |
