Connect Your Raspberry Pi and Arduino Uno!

Both the Raspberry Pi and Arduino Uno are very powerful devices, good at different things. The Arduino boards are awesome at reading inputs and outputs from various different things. The Raspberry Pi is basically a mini, open-source Linux computer. If you put these two together, your options are limitless.

That's what this tutorial is about. Putting these two together, over USB and Serial Communication! Let's get started.

Step 1: Materials List

In order to get a good understanding of this project, you will need the following materials:

Raspberry Pi B+
Arduino Uno
Breadboard
Jumper Cables (4)
LEDs (3)
220 OHM resistors (3)

You can use the same colored LEDs if you wish, but different colors are easier to visualize.

Step 2: The Circuit

The circuit itself is very simple. Follow the diagram and you'll be good to go.

Step 3: Arduino Code

In order to install run Arduino on your Raspberry, you will need to type the following into the LXTerminal. You could also try to download the Linux ARM file, but I couldn't get it to open on the Raspberry pi.

sudo apt-get update && sudo apt-get install arduino

note: you must have an internet connection

(source: http://playground.arduino.cc/Linux/Raspbian )

Now that you have Arduino on the Raspberry Pi, copy and paste this code into your sketch:

char receivedChar;
boolean newData = false;
void setup() {
  Serial.begin(9600);
  pinMode(3, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  
}
void loop() {
  recvInfo();
  lightLED();
  
}
void recvInfo() {
  if (Serial.available() > 0) {
    receivedChar = Serial.read();
    newData = true;
    
  }
  
}
void lightLED() {
  int led = (receivedChar - '0');
  while(newData == true) {
    digitalWrite(led, HIGH);
    delay(2000);
    digitalWrite(led, LOW);
    newData = false;
    
  }
  
}

Plug your Arduino into the Raspberry Pi via USB and upload the code!

Step 4: The Raspberry Code

Now, it's time to make everything fall into place. Enter the following code to set up serial communication between the Arduino and Raspberry. Go to the Desktop and open the IDLE application, and type the code in there.

 >>> import serial
 >>> ser = serial.Serial('/dev/ttyACM0', 9600)

Once that code is entered, it is time for us to begin communication!

Step 5: Communication!

As you know, the circuit includes three LEDs. The red LED is connected to pin 3, the green connected to 5, and the yellow connected to 6. You can use different colors if you like, but those are what I chose. Type these commands into the IDLE program.

Turn red LED on:

>>> ser.write('3')

Turn green LED on:

>>> ser.write('5')

Turn yellow LED on:

>>> ser.write('6')

When a command is entered, the LED told to turn on will light for 2 seconds, and turn back off! Now that you know how to do this, expand this idea into other things like servos, LCD screens, or whatever you can think of that communicates with Arduino!