Connecting Arduino and Raspberry PI over GPIO
There are obvious reasons why you would want to connect an Arduino with your Raspberry – they can just perfectly work together and play out their strengths (for instance reading analog inputs on the arduino side and interacting with the web or doing more complex stuff on the Raspberry). But connecting the two devices is not as easy as you might think, especially as they are working on a different voltage level, the Raspberry on 3.3v and the Arduino on 5v. Of course you will find many ways to connect the two nevertheless on the web, you can go straight over USB (which i find a little bit less…sexy), you can connect them wireless, via a serial connection or directly over a PIN-Connection between the two boards. But be careful – because of the different voltage levels it’s not a good idea to just connect them, you have to adjust the voltage unless you want to kill the RPi. One way is to use a logic level converter (like this one from Sparkfun or this from Adafruit). But i was wondering (with my naive electronic know how in full action) why you shouldn’t just use a normal voltage regulator like the great Recom R-783.3. So i checked, and it worked absolutely fine as you can see in the video below.
The video shows an Arduino which runs a simple sketch to put digital pin 8 on high and low level every second, connected to the RPi over the Recom which reads this input on Pin 5 and powers Pin 7 as output accordingly so that the LED finally will blink…
[youtube]http://youtu.be/OA8Ijp6CGV0[/youtube]
I think this is interesting because of the better availability of such a dumb regulator compared to the logic level converter, so you are quicker up and running. In general the logic level converter will be the better choice, it’s actually cheaper, it’s also save for regulating a serial connection (i didn’t test this with my Recom) and it comes with more channels right away.
If you are interested in more Maker-Content of this kind – i’ve moved this into a separated blog.