Raspberry Pi and Arduino: Good Friends

January 31, 2013 ~ Steve ~ 1 Comment

I have a Raspberry Pi and it’s pretty great. I have an Arduino Esplora and an Arduino Micro and they are fun. Though, as I’ve played more with the Arduino I’ve found one totally understandable drawback: it’s more or less local only. I mean that the data that comes back through sensors or the items being controlled only send response back over serial or USB/serial. It makes sense but it also limits what can be done with it when used all by itself. One of my early ideas for a project was to use a light and a temperature sensor to keep an eye on aging homebrew beer. Nothing super fancy, just records the information for viewing and alerting when the sensors see data outside of the accepted norms. I could do this with some LED’s, buzzer or a display that would notify me when things were off but that isn’t really the type of alerting I’d like to see. That type of alerting would require me to go look at the box for information. I might as well do the sensor gathering manually with my eyes and feeling inside the box. It also means the data would be lost on every iteration. Data from 10 minutes ago could only be gathered if I was present 10 minutes back. Enter Raspberry Pi.

The Raspberry Pi is able to power the Arduino Esplora and, likely, the Arduino Micro. Since communication is over USB/serial the Raspberry Pi can collect the data from the sensors and provide a networked view into the data. For instance, a web interface showing temperature and light graphs. And, best yet, it’s simple to add a USB wireless adapter to the Pi to avoid running an ethernet cable back to the network.

Now, from what I read, it’s possible to use Raspberry Pi itself without an Arduino to collect data and control devices but it requires an ADC for analog input/output. But there is something that seems more proper about separating the physical logic (using C in Arduino) from the notification and reporting logic (using Python on a Raspberry Pi). It feels almost MVC like.

In any case, if you are looking at doing some analog and digital stuff with a Raspberry Pi do know that adding a small Arduino makes life easy and, if you decide to change to another device for providing network views it should be a simple switch over.

Hi Arduino Esplora

January 26, 2013January 26, 2013 ~ Steve ~ 2 Comments

Last night I ordered some sensors for use with my new Raspberry Pi but I just could not wait to play with sensors. I ran up to the closest electronics store at 10am to buy the last Arduino Esplora in stock.

This is a pretty new addition to the Arduino line up. It comes with multiple sensors pre installed on the board as well as a library to make programming with the sensors a little too easy. It’s a bit pricier than the other boards but for something to learn on and do some random project prototyping it seems ideal.

After about 15 minutes I was already reading data off the sensors and reading it back from the serial console. But since I want to learn more about using the sensors I’ll be porting the project to the lower level API once I’ve finished prototyping on the Esplora library. The Esplora library makes it really easy but I feel like it’s hiding a lot of I want to learn. At this point I have a periodic temperature check which is holding current temperature, all time and relative averages and printing it back over serial in JSON. Now I just need to figure out how to both power the board and get its data over to either a Raspberry Pi or machine somewhere so I can trend and alert. I’m worried about the differences in volts between the two but I’m sure there is a safe way to interface and power. My first project is to keep an eye on the temperature and light levels of my homebrew to ensure proper aging!

Hello Raspberry Pi

January 25, 2013January 26, 2013 ~ Steve ~ Leave a comment

I couldn’t help it. I’ve watched other open source friends rave about playing with the Raspberry Pi but had yet to really jump in on it all. See, I bought a GuruPlug a while back and had kind of a bad experience with it. You know, overheat and shut off. In fairness the manufacturer of the device did provide a hardware fix quite a while later, but I’d already moved on and forgotten why I bought the device in the first place. It took the consistant praise from online friends and one conversation with my friend Andrew to get me to take the plunge.

Yesterday it arrived in a nondescript package. A simple yellow padded envelope. Opening it up I saw two small boxes. Funny thing is the larger of the two boxes is actually the wall plug. But I didn’t have time to do anything other than prepare an SD card with raspbian on it. But today I’ve thrown it on the network (headless) and have an ssh connection in to update the default system.

Now I’m at a bit of a loss or, I should say I’m not sure where to start. I picked up a breadboard, wires and LED’s to do a little playing around. I’m just not sure what I want to do for a longer term project. I’d like to start working with some sensors and pick up more knowledge in that space. I have some more components on the way but it will be a while. Maybe I’ll snag a Arduino while I wait.