Control Arduino from Raspberry Pi with pyFirmata
- Raspberry Pi with Raspbian OS installed in it
- Arduino Uno or any other Arduino board
- Arduino USB cable
Installing PyFirmata in Arduino using Raspberry Pi
To upload PyFirmata firmware in Arduino, we have to install Arduino IDE in Raspberry Pi. Follow these steps to install:
Step 1:- Connect the Raspberry Pi to the internet. Open command terminal and type the following command and hit enter
sudo apt-get -y install arduino python-serial mercurial
Wait for few minutes, it will take time. This command will install the Arduino IDE in your Raspberry Pi.
Step 2:- Now, we will install pyFirmata files using the given github:
git clone https://github.com/tino/pyFirmata
Then run the following command:
cd pyFirmata sudo python setup.py install
Step 3:- We have installed all the required files and setups.
Now, connect your Arduino board with Raspberry Pi using USB cable and launch Arduino IDE by typing arduino in terminal window.
Step 4:- Then type lsusb command to check whether Arduino is connected with your raspberry pi.
In Arduino IDE, Go to tools and choose your board and Serial Port.
Step 5:- Upload the PyFirmata firmware on the Arduino by clicking File -> Examples -> Firmata -> Standard Firmata and then click upload button . As shown below.
We have successfully installed the pyFirmata firmware in the Arduino board. Now, we can control our Arduino using Raspberry Pi.
For demonstration we will blink and fade an LED on the Arduino by writing python codes in Raspberry Pi.
So let’s start writing the code
Open your favorite text editor on the Raspberry Pi and import pyFirmata library.
Define pin on the Arduino to connect the LED
led_pin = 9
Now, we have to write serial port name on which Arduino board is connected using pyfirmata.Arduino() function and then make an instance by assigning port in board variable.
board = pyfirmata.Arduino("/dev/ttyACM0") print "Code is running”
In while loop, make led pin HIGH and low using board.digital.write() function and give delay using board.pass_time() function.
while True: board.digital[led_pin].write(0) board.pass_time(1) board.digital[led_pin].write(1) board.pass_time(1)
Our code is ready, save this code by putting .py extension to the file name.
Open command terminal and type python blink.py to run the code on the Arduino board. Make sure your Arduino board is connected with your Raspberry Pi board using USB cable.
Now, you can see Blinking LED on the Arduino board.
Complete code for blinking LED using pyFirmata is given at the end.
Fading LED on Arduino using pyFirmata
Now, we will write code for fading the LED to make you more familiar with the pyFirmata functions. This code is easy as previous one. You have to use two for loops, one for increase brightness and other for decrease brightness.
In this code, we have defined the pins in different way like led = board.get_pin(‘d:9:p’) where d means digital pin. This is function of pyFirmata library. Read the documentation for more details.
Complete code for Fading LED using pyFirmata is given at the end.
Now, you can add more sensors to your system and make it more cool, check our other Arduino projects and try building them using Raspberry pi and python script.
Python code for LED blink:
import pyfirmata led_pin = 9 board = pyfirmata.Arduino("/dev/ttyACM0") while True: board.digital[led_pin].write(0) board.pass_time(1) board.digital[led_pin].write(1) board.pass_time(1)
Python code for Fading LED:
import time import pyfirmata delay = 0.3 brightness = 0 board = pyfirmata.Arduino("/dev/ttyACM0") led = board.get_pin('d:9:p') while True: # increase for i in range(0, 10): brightness = brightness + 0.1 print "Setting brightness to %s" % brightness led.write(brightness) board.pass_time(delay) # decrease for i in range(0, 10): print "Setting brightness to %s" % brightness led.write(brightness) brightness = brightness - 0.1 board.pass_time(delay)
Linux, Debian remove / stop service
To stop a service
sudo service servicename stop
To disable service autostart
sudo update-rc.d servicename disable
Raspberry turn off usb ports
You can control the power on a port using the following command. (I installed it in user bin directory)
sudo $HOME/bin/hub-ctrl -h 1 -P 2 -p 1
That says to control hub 3 (-h 3) port 1 (-P 1) and to turn the power off (-p 0). You can also use ”-p 1” to turn the power back on.
Raspberry: upload Arduino sketch from CLI
install these packages
sudo apt-get install arduino-core arduino-mk
Then add yourself to the dialout group to allow you to upload code to the Arduino board
sudo usermod -a -G dialout pi (Change pi to be your username if different)
ARDUINO_DIR = /usr/share/arduino
BOARD_TAG = uno
ARDUINO_PORT = /dev/ttyACM*
Crontab on Linux
To launch a program at reboot.
Add following line to crontab file:
@reboot sudo python /home/pi/hw-home.py /home/pi/hw-home.txt