Arduino Development for OSX and iOS (2015)

3. Controlling Arduino from OSX

3.4 Demo

To illustrate how to control Arduino from Mac machine, we build a demo. We use three LEDs which are turned on/off from OSX.

The following is a hardware wiring:

· LED 1 is connected to Arduino digital pin 10

· LED 2 is connected to Arduino digital pin 9

· LED 3 is connected to Arduino digital pin 8

You can see my hardware implementation as below.

3.4.1 Writing Python Program

Now we write a program for our demo using Python.

Open your favorite editor and write these scripts.

from pyfirmata import Arduino

import time

board = Arduino('/dev/cu.usbmodem1411')

led1_pin = 10

led2_pin = 9

led3_pin = 8

def turn_off_all():

board.digital[led1_pin].write(0)

board.digital[led2_pin].write(0)

board.digital[led3_pin].write(0)

# turn on LED sequentially

try:

while 1:

print('LED1 is ON')

board.digital[led1_pin].write(1)

time.sleep(1)

turn_off_all()

print('LED2 is ON')

board.digital[led2_pin].write(1)

time.sleep(1)

turn_off_all()

print('LED3 is ON')

board.digital[led3_pin].write(1)

time.sleep(1)

turn_off_all()

except KeyboardInterrupt:

turn_off_all()

print("done")

Code explanation

· We initialize Arduino board on specific port using Arduino() . Please change Arduino serial port

· To turn on LED, we call board.digital[pin].write(1) which pin is digital pin

· To turn off LED, we call board.digital[pin].write(0) which pin is digital pin

Save these scripts into a file, called firmatademo.py.

3.4.2 Testing

Now you can test the program, type this command.

$ sudo python firmatademo.py

You should see the program output on Terminal.

You also should see blinking LEDs.