The PCF8575 is controlled through an I2C interface and features 16-bits
of quasi-bidirectional input/output pins. On board 3.3V level converter
circuit, if you do not solder VCC-VDD pad, the PCF8575 level is 3.3V.
16-bit input/output port expander with interrupt output
Cascadable for up to 8 devices on one bus
25mA sink/source capability per I/O
Supports 100kHz, 400kHz and 1.7MHz I2C™Compatible compatible modes