user19603: I have a rather ambitious project in mind. Lots of buttons, sensors, feedback.
If I run out of GPIO ports to attach stuff to my Arduino, what's next? Do you have to buy a separate Arduino to run the extra parts, and then link the two arduinos somehow?
Thanks for any direction you can give.

user15180: Yes, it is one possible way, another are using some kind of multiplexing as input shift registers, Charlieplexing http://www.instructables.com/id/Charlieplexing-7-segment-displays/?ALLSTEPS, button matrix http://pcbheaven.com/wikipages/How_Key_Matrices_Works/ or i2C bus, which can connects up to 127 different i2c devices

19603: <p>I have a rather ambitious project in mind. Lots of buttons, sensors, feedback.</p>

<p>If I run out of GPIO ports to attach stuff to my Arduino, what's next? Do you have to buy a separate Arduino to run the extra parts, and then link the two arduinos somehow?</p>

<p>Thanks for any direction you can give.</p>
 15180: <p>Yes, it is one possible way, another are using some kind of multiplexing as input shift registers, Charlieplexing <a href="http://www.instructables.com/id/Charlieplexing-7-segment-displays/?ALLSTEPS" rel="nofollow noreferrer">http://www.instructables.com/id/Charlieplexing-7-segment-displays/?ALLSTEPS</a>, button matrix <a href="http://pcbheaven.com/wikipages/How_Key_Matrices_Works/" rel="nofollow noreferrer">http://pcbheaven.com/wikipages/How_Key_Matrices_Works/</a> or i2C bus, which can connects up to 127 different i2c devices</p>
