Connect Your Raspberry Pi and Arduino Uno!




About: Building and coding is what I do.

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: )

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

char receivedChar;
boolean newData = false;

void setup() {


pinMode(3, OUTPUT); pinMode(5, OUTPUT); pinMode(6, OUTPUT); }

void loop() {

recvInfo(); lightLED(); }

void recvInfo() {

if (Serial.available() > 0) {

receivedChar =; 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!

Step 6: Troubleshooting and Useful Links!

Raspberry Pi doesn't recognize the Serial port '/dev/ttyACM0' ?

The serial port could have a different name! To check....

1. Go to LXTerminal.

2. Unplug your Arduino.

3. Type in

ls /dev/tty*

4. Plug in Arduino.

5. Repeat step 3.

6. Check for a new directory file between the two times. The one that only shows up the second time is what you should use!

LEDs don't light when they should?

Check your wiring. Are your LEDs facing the right direction? Are your LEDs connected to the right pins? Always double check!

Serial Communication with Arduino -

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    22 Discussions


    Question 23 days ago on Step 6

    Hi! On another blog they commented that tying the two devices directly together by the serial port was risky because the Rasberry PI IS 3.3V and the Arduino was 5V, thereby risking damage to the Pi... is this an issue or an outdated problem?


    5 weeks ago

    Thanks for this Instructables.
    Very helpful.


    8 weeks ago

    Excelente, mas não se esqueçam de instalar a serialport (npm install serialport@6.2.2 --save).


    2 months ago

    why i could not upload these programs, can you help me ,please ?

    Screenshot (51).pngScreenshot (52).png

    Question 4 months ago on Introduction

    I would like to send data from Arduino to raspberry pi using Bluetooth. Someone kindly guide me....


    2 years ago

    the command " ser.write('3') " is not working. I checked the leds they are fine and their polarity is also correct. what might be the problem here?

    2 replies

    Reply 8 months ago

    add "str.encode" before the ('3').
    should look like this:


    Reply 1 year ago

    Use Python 2 (IDLE). Run the module file then enter 'ser.write('3')' in the shell.


    Question 9 months ago on Step 4

    beautiful tuturial
    but I have a question
    how can i read the status of the arduino inputs on rastberry?
    and why is it that when I dial an output with the number above 9 it does not turn on?
    thank you


    10 months ago

    sir greatwork that u have done same i too did ..can u turn on the LED through your voice by using input as Microphone.LED should be turned only after recogning your can we try this.can u guide me can u tell me how to send the commands from raspberrypi to arduion


    Question 1 year ago

    pi@raspberrypi:~ $ sudo apt-get install arduino

    Reading package lists... Done

    Building dependency tree

    Reading state information... Done

    E: Unable to locate package arduino

    is there a diffrent command i can type in to install the arduino ide on the raspberry pi?


    1 year ago

    +1! Great, simple tutorial


    1 year ago

    Thanks for share this project, it was so easy and also elegant to make this connection I am very happy with the results, I was looking for such connections but only find difficult and not cristal clear projects. This one realy works. Thanks.


    1 year ago

    Dude. Please help me . We have a thesis. How can i connect rasbery pi to arduino? is there any application i can used? Heeelp me i need to run arduino using rasbery pi please here is my fb. cexz.quilala and my email @cexz.quilala. Please i will pay if u want please asap. jut pm me

    1 reply

    Reply 1 year ago

    You need to do this for a thesis? This is easy man, and there are tons of guides online of multiple ways to do it! Spend more then 10 minutes googling and i'm sure you'll find a a few step by step or video guides.


    1 year ago

    Hi. I am reading this prior to buying an Arduino board, so I can not see, what happens live.

    I actually do not see, how one does:

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

    but I guess it will be obvious after performing

    sudo apt-get install arduino

    Will it? Or do I have to start some kind of UI on Raspberry?

    My other question is: Will all this work with Leonardo or other boards like Mini, Micro, Pico or whatever?

    Thank you for answer.


    2 years ago

    Great for learning the basics of getting the Pi to talk to the Arduino with minimum effort.


    2 years ago

    can someone tell me where in the breadboard the jumper wires are going? I can't read it from the picture, and yes i'm a beginner so I think it would be logic but I don't understand ha ha


    2 years ago

    I want to connect two arduino or more to a raspberry pi using serial commmunication via usb gor my latest project .....

    Sir plz plz plz help me ..... coz i m a begginer ?????


    3 years ago

    For this simple example, you're actually making it a bit more complicated than you need to. Instead of getting into python, all you need is echo "1" >/dev/ttyACM0 (note, /dev/tty is not a directory, e.g. /dev/ttyACM0 not /dev/tty/ACM0). You should also look at for info on how to easily configure the arduino port characteristics, e.g baud rate (note, I add -hupcl to the string listed to keep the arduino from rebooting each time the device is opened). Note also that sometimes arduinos appear as /dev/ttyUSB0 instead of /dev/ttyACM0. It's also handy to know there is a symbolic link at /dev/serial/by-id that includes the usb id in the file name. This is really useful if you have more than one arduino attached to your system because ACM0, ACM1, etc. can change if you plug and unplug the arduino but the usb id can't.