Raspberry Pi, Arduino and node.js

Putting them all together

I wrote about installing Drupal 7 on the Raspberry Pi and about installing node.js on the Raspberry Pi. Now I am writing about adding an Arduino. The Arduino will communicate with the Raspberry Pi over Ethernet. My setup uses an Arduino Uno with an Ethernet Shield. I imagine you could use any of the Ethernet capable Arduino variants as well.

The Hardware List

• Raspberry Pi Model B (512MB) loaded with Raspbian "wheezy"
• Arduino UNO R3 board with Arduino Ethernet Shield R3
• Ethernet switch or router
• Computer setup to program the Arduino and ssh to the Rapberry Pi

Raspberry Pi and node.js

Load the Raspbian "wheezy" image on your Raspberry Pi. (You can find directions for this on the Raspberry Pi website.) I suggest installing a LAMP stack and Drupal 7, you will at least need to install MySQL. Install node.js on the Raspberry Pi as I outlined in this earlier post. Then create a new file named server.js and copy the node.js code from my Arduino and node.js post. Install MySQL if you haven't and setup the required database and user as outlined in the Arduino and node.js post. Run the node.js program with the command node server.js This will start the node.js server listening on port 8080. Note the Raspberry Pi's IP address so you can edit the Arduino code to point to it. I use the command ifconfig to get the Raspberry Pi's IP address.

Arduino and Ethernet Shield

If this is your first time programming an Arduino then head over to arduino.cc and read the Getting Started Section. Create a new sketch and copy and paste the arduino code from my previous post about Arduino and node.js. Edit the server IP address and name to match that of your Raspberry Pi. If you are not using a DNS server then you can bypass that code by commenting out the line that assigns the DNS IP address to the receiver IP address. The Arduino code samples the analog input pin A0 and writes it to a node.js server every 10 seconds. During start-up the arduino will write its IP address and the server IP address to the USB serial communication port. With the Ethernet shield installed on the Arduino Uno connect it to the Ethernet network. Load the sketch to the Arduino over a USB cable and then open the serial port monitor. If your network is setup with a router that servers up DHCP addresses then the Arduino should print its address to the serial port monitor.