I need lots of digital IO on a uno board...

Hi, I'm using a uno board with ethernet shield and I need about 15 in- and 15 outputs. What is the best way to do this?

The uno should have 14 digtal outputs, but pin 0 and 1 are used serial, with the ethernet shield pin 4, 10, 11, 12 and 13 are also in use. So this reduces it to 7.

Any suggestions?


Multiplexers (on inputs) and demultiplexers ( on outputs ) IC chips would solve a problem.
For outputs you can use a registers as well.

or this one - http://macetech.com/store/index.php?main_page=product_info&cPath=4&products_id=23
It has an address jumper so you can stack two of them giving you 128 I/O lines.

It has 64 IO lines and is controlled over the I2C bus, so it only uses analog pin 4 and 5 of the Arduino.

Hopes this helps,

will that board work with the Bare Bones board?

Which bare bones Arduino?

Actually, since it comes without the header soldered on, you can set the Centipede Shield off to one side and just run 5V, GND, A4, and A5 wires over the the Centipede Shield. If you're using the Ethernet Shield on a standard footprint Arduino, there's likely to be a stacking issue anyway...since the Ethernet Shield and the Centipede Shield both have tall components.