Description

You're lack of inputs/outputs on your editing electronic arduino, and there's enough pine for an I2C link.

This circuit will allow you to add 8 inputs/outputs controllable in series with the I2C connection.

It is also possible to up to 8 on the m ^ line me I2C by using the pines of addresses, either 64 input/output on a single line series.

Tutorial

Tutorial: Arduino I/O Port Expander PCF8574 with