Connect arduino with raspberry pi: Raspberry Pi Arduino Serial Communication — Everything You Need To Know

How to Control an Arduino from a Raspberry Pi

The “Should I use a Raspberry Pi, or should I use an Arduino?” question always comes up in the first stages of product development. Honestly, who wouldn’t be confused? Both boards are insanely popular, but there are subtle differences in their optimal use cases.

The Raspberry Pi is a computer, so it uses an operating system. This creates multiple layers of abstraction that make real-time signal generation and detection unreliable. On the other hand, the Arduino can read and write electronic signals much faster and more reliably than the Raspberry Pi.

Luckily the Arduino and Raspberry Pi can be used together in the same project to take advantage of features from each board.

In this tutorial we will learn how to control the Arduino’s GPIO pins with a Python program run by the Raspberry Pi. The Arduino can be connected to the Raspberry Pi directly with a USB cable. To do this we will use a protocol called Firmata.

Firmata

Firmata is a communication protocol that connects a microcontroller to software on a host computer. Think of Firmata as a language that the Raspberry Pi and the Arduino both understand.

Setting Up the Arduino

The easiest way to setup Firmata on the Arduino is by using the Raspberry Pi. First, we need to install the required software.

1. Connect the Raspberry Pi to the internet. Open command terminal and enter the following command:

sudo apt-get -y install arduino python-serial mercurial

2. Now, connect the Arduino to the Raspberry Pi with an A to B USB cable.

3. Open the Arduino IDE, and select the correct port for the device.

4. Next, upload the PyFirmata firmware to the Arduino by opening the sketch from File > Examples >  Firmata > Standard Firmata.

5. Finally, click the upload button.

Setting Up the Raspberry Pi

To prepare the Raspberry Pi:

1.  First, install the pyFirmata files by entering this:

git clone https://github.com/tino/pyFirmata

2. Then, run the following commands:

cd pyFirmata
sudo python setup.py install

Preparing the Hardware

To demonstrate how Firmata works, we will build a project that uses a Python program on the Raspberry Pi to control the Arduino’s GPIO pins. We will connect a button and LED to the Arduino so that the LED lights up when the button is pressed.

To build this project, we need the following components:

• Raspberry Pi
• Arduino Uno
• Jumper wires
• Breadboard
• Tactile push button
• One LED
• One 220 Ohm resistor
• A to B USB cable

Follow this diagram to connect the LED and push button to the Arduino. The Arduino is connected to the Raspberry Pi with an A to B USB cable:

Figure 1: Hardware connections

To learn more about the Arduino, check out our Ultimate Guide to the Arduino video course. We teach Arduino programming and circuit building techniques that will prepare you to build any project.

Python Code

Copy the code below to your Raspberry Pi and save it as a “.py” file. Run the program by typing python filename.py:

import pyfirmata
led_pin = 7
button_pin = 8
board = pyfirmata.Arduino("/dev/ttyACM0")
while True:
    if board.digital[button_pin].read(1):
        board.digital[led_pin].write(1)
    else:
        board.digital[led_pin].write(0)

Code Explanation

First, we import the pyfirmata library using import pyfirmata. Then we label the LED and button pins by storing them into variables: led_pin and button_pin. To make this program connect to the Arduino, we need to tell it the port where the Arduino is connected. Use pyfirmata.Arduino() and then create the instance by assigning the port in the board variable. In this case it’s /dev/ttyACM0.

The while loop basically acts like void setup(). We use an if statement to monitor the status of the button. If the button sends a HIGH signal, meaning it was pressed, the LED lights up. Both use the digital[].read and digital[].write methods to control the GPIO pins on the Arduino.

Now when you press the button the LED should light up. Press CTRL + C to stop the program.

Hope this tutorial has helped you to understand how to control the Arduino with a Raspberry Pi. Leave a comment below if you have any questions!

Programming an Arduino from Raspberry Pi

Problem

You want to run the Arduino IDE on a Raspberry Pi so that you can write and upload programs onto an Arduino.

Solution

The Arduino IDE is available for the Raspberry Pi. It is a little bit slow, but usable. Use these commands to install it:

$ sudo apt-get update
$ sudo apt-get install arduino

At the time of writing, this installs version 1. 0.1, which is not the latest version but will suit the Arduino Uno; it will not, however, work for newer boards like the Leonardo and Due. They can still be used with the Raspberry Pi, but you will need some other computer to program them before connecting them to the Raspberry Pi.

After installation, you will find an Electronics group in your Programs menu (Figure 10-1).

Figure 10-1. The Arduino IDE running on Raspberry Pi

The Arduino IDE connects to the Raspberry Pi through its USB cable to program it. This connection also requires that the serial console be disabled. You can follow “Freeing the Serial Port” to do this, but a second option is to run a script created by Kevin Osborn that both disables the serial console and configures the serial ports and Arduino profiles necessary to get things running. This has the advantage that it also sets up the aLaMode board to be ready for use (“Getting Started with an aLaMode Board and a Raspberry Pi”).

To download and run this script, follow these steps:

$ wget https://github. com/wyolum/alamode/blob/master/bundles
  /alamode-setup.tar.gz?raw=true -O alamode-setup.tar.gz
$ tar -xvzf alamode-setup.tar.gz
$ cd alamode-setup
$ sudo ./setup

If you have not previously disabled your serial console and are relying on the preceding script to do it, then you will need to reboot for this change to take effect.

$ sudo reboot

You can now connect your Arduino to your Raspberry Pi. From the Tools menu, select Board and set the board type to Arduino Uno. Then, from the Serial Port option, select /dev/ttyACM0. To upload a test program that will make the LED on the Arduino blink, select the File menu and then click “Examples, Basic,” and finally click Blink. Click on the right-arrow on the toolbar to begin the compile and upload process. If all is well, you should see a “Done Uploading” message in the status area at the bottom of the IDE window.

If you find that the device ttyACM0 is not listed even though your Arduino is plugged in, try restarting the Arduino IDE. If that doesn’t work, then you may have to reboot your Raspberry Pi. Leave the Arduino connected while you reboot and restart the Arduino IDE.

Discussion

To get the most out of using Arduino with Raspberry Pi, you need to learn a little Arduino programming. You may find the book Programming Arduino: Getting Started with Sketches (McGraw-Hill/Tab Books), by yours truly, helpful.

You can, however, make use of an Arduino without needing to write any code on the Arduino side, using a project called PyFirmata. “Setting up PyFirmata to Control an Arduino from a Raspberry Pi” explains how to use PyFirmata.

See Also

The Arduino IDE setup script came from the blog Bald Wisdom.

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Connecting Raspberry Pi 3 and Arduino UNO R3 — Real Notes Ubuntu & Mikrotik

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In order to expand the capabilities of my Raspberry Pi 3 Model B minicomputer, I connect a device based on the Atmega328P microcontroller to it. What is remarkable is the Atmega328 microcontroller installed on the Arduino UNO R3 board can be powered from the USB connector, which in the current task will only work for me. nine0003

The circuit I want to disassemble:

Raspberry Pi 3 Model B + USB Arduino UNO R3

Steps:

• I burn the image of the operating system Raspbian to MicroSD
  

• I connect a minicomputer Raspberry Pi 3 to the monitor via an adapter HDMI to VGA , I also need a mouse and keyboard
• Connecting a network cable from my home router RB2011UiAS-2HnD
• Performing the initial setup of the minicomputer
• Enable remote connection via VNC and SSH
• Turn off monitor, mouse and keyboard
• Using a USB cable I connect a minicomputer Raspberry Pi 3 Model B with a Arduino UNO R3 board
• Next, I connect from my home laptop Lenovo E555 system Ubuntu Trusty Dekstop amd64 Gnome Classic via the Remmina client ( VNC connection) to the Raspberry Pi 3 Model B minicomputer.

 #!/usr/bin/python# -*- coding: utf-8 -*-# Chip address PCF8574i2c_addr = 0x20#

import the necessary libraries

import smbus as smbus

import RPIOfrom time

import *from subprocess

import Popen, PIPE

#configure I2C bus for functionsi2c = smbus.SMBus(1)# Configure GPIO port 25 and pull it to ground.

RPIO.setup(25, RPIO.IN, pull_up_down=RPIO.PUD_DOWN)# Here is what we do when the interrupt arrives def gpio_callback(gpio_id, val):

 try :

 # Read from PCF8574

temp = i2c. read_byte( i2c_addr)

print 'PCF8574 at address 0x{0:2x} READ 0x{1:2x}'.format( i2c_addr, temp )

except IOError : print 'PCF8574 Device not found at I2C address 0x{1:2x}'.format( i2c_addr )

error = 1

# Button pressed on port P4

 if (hex(temp)== hex(0xdf)):

 # Here I pull the screen, the connection of which I described in the last entry.

 #p = Popen('/home/pi/mj/LCD-Char/LCD-Test-mj-v4.py Key=1 1 VAL=Press 2', stdout=PIPE, shell=True)

 print("gpio %s: %s" % (gpio_id, val))

# Button pressed on port P5

 if (hex(temp)== hex(0xef)):

#p = Popen('/home/pi/mj/LCD-Char/LCD-Test-mj-v4.py Key=2 1 VAL=Press 2', stdout=PIPE, shell=True)

 print("gpio %s: %s" % (gpio_id, val))

# Both buttons are pressed at the same time

if (hex(temp)== hex(0xcf)):

#p = Popen('/home/pi/mj/LCD-Char/LCD-Test-mj-v4.py Key=1+2 1 VAL=Press 2', stdout=PIPE, shell=True)

print("gpio %s: %s" % (gpio_id, val))

flag=1

# Set up the port to wait for interrupts and execute the above function

RPIO.add_interrupt_callback(25, gpio_callback, pull_up_down=RPIO.