The Arduino/Raspberry Pi combo I’m using for my pizza oven failed completely last weekend, just in time for the biggest event the oven’s had!

We had a party Saturday night, so I lit the oven about lunch time Saturday and cooked a couple of pork bellies, then made pizzas when people arrived for tea. So the oven was fired for 8 hours or so straight. I would have loved to see how the temperature travelled through the walls being fired for that long. But it wasn’t to be.

I am powering the Arduino through a USB connection from the Raspberry Pi, which is I think a mistake. Still, it’s been fine until now. The whole thing is powered by a 12 volt power supply inside, feeding through the spare wires in the ethernet cable, which is fairly long. From the cable it goes through a cheap 12v -> 5v (USB) power converter into the Raspberry Pi, which has a USB connection that powers the Arduino, and lets the Pi pull temperature readings from the Arduinos thermocouple shield. It’s worked fine for over 12 months!

But now if I power the Pi up itself it works fine, but when I plug the Arduino in and initialise the serial the whole thing dies.

I have been wanting to build a decent 12v -> 5v power supply for a while, and power both devices directly from that. Or even better, find a thermocouple interface for the Pi that handles 8 thermocouples so I can get rid of the Arduino altogether.

I guess now that this is happened I finally have the incentive to built that power supply, or two of them, so I can use one in my car as well.

Raspberry Pis are great little machines. A PC in a couple of inches of circuit board! They make it so easy to develop applications. What can you do with a computer that would fit in your show? Anything you want.

I have a pizza oven that I built myself. Part of the design involved being able to record temperatures. So I originally installed some thermocouples from eBay, and an arduino with a thermocouple shield. Arduinos are also fairly cool, but are a bit harder to deal with and more limited software wise. And everything is an expansion. So I had to buy an Ethernet shield to get network connectivity.

I wanted to set it up so that my computer inside could connect to the arduino and grab the temperatures. I never really got it to work. I could work it with the Arduino connecting to the internal server, but not theother way around. The arduino just kept locking up.

After a lot of fiddling I got my hands on a raspberry pi. This was more like it. A Linux machine! I know Linux! I still needed the arduino to run the thermocouples, but connected it to the raspberry pi using USB. The USB fed the power and also let me poll the temperature readings through the serial interface. And then a simple web app using Ruby Sinatra lets my internal machine poll the readings as needed. The data goes into a MySQL database and generates pretty graphs.

Anyway, back to the point. My raspberry pi has stopped working. It’s mounted on the back of my pizza over in a plastic box. When I turn the power on, I can ping it for around ten seconds and then it stops. So I’m going to need to pull it out and connect a monitor and see what’s happening.

The point of all this is that while implementing these things is fun, the more you use them for around your home, the more you end up spending your home time doing free IT support!.

The fun is all in the implementation. Once that’s over, supporting it is just a chore!