This is a TinyWireM library for the MCP23017 I2C 16-bit bidirectional GPIO expander.
The library uses TinyWireM so that it can be used with ATtiny devices like the 85.
TODO:
- support more than one 23017.
- add a function to provide fast bit tests. Right now to test a bit it reads both 8-bit sets of pins and then compares. In theory you only want to read 16-bits once per loop then just test which bits are set.
- Support interrupts/etc (though this might be impractical with 8-pin tiny chips)