increasing I/O pins in arduino also voltmeter

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello all once again thanks for all the help i recieved thus far my project is coming along nicely but im running into some problems i have like 3 atmega chips im really only using one is there a way i can connect two of them to increase the number of pins cause i just ran out of I/Os,...or whats the easiest way to increase the number of I/O's ....plus in my project i need to measure the voltage of a system with a voltmeter used by a user and when they check it have the numerical information inputed back to the microcontroller code and checked against additional information. Is there a chip that i can add to my design that does that or a way i can open a voltmeter and rewire it to do such....ANY IDEAS FOLKS

2

Adding extra inputs or outputs is something people do all the time. There are many ways to do this, the most popular is by using a shift register.

Depending on if you want extra inputs or outputs use:-

Or:-

For general interfacing see:-
http://www.arduino.cc/playground/Main/InterfacingWithHardware

You can use the analogue input of the arduino with a suitable potential divider to measure voltage.

3

I presume you need more pins than the new Arduino Mega provides? It has something like 54 digital pins and 15 analog.