pyArduinoAPI 0.8.2

A light-weight Python library that provides a serial bridge for communicating with Arduino microcontroller boards. Extended to work with Python 3

pyArduinoAPI

A Python API for communicating with your Arduino board.

A lightweight Python library for communicating with Arduino microcontroller boards from a connected computer using standard serial IO, either over a physical wire or wirelessly. It is written using a custom protocol, similar to Firmata.

This is my own fork of the original version of this repo. I've added some new commands to suit my needs and use cases for Arduino, and will continue adding my modifications here as I need them.

This library allows a user to quickly prototype programs for Arduino using Python code, or to simply read/control/troubleshoot/experiment with hardware connected to an Arduino board without ever having to recompile and reload sketches to the board itself.

Method names within the Arduino-Python3 Command API are designed to be as close as possible to their Arduino programming language counterparts. This allows for Arduino code to quickly be transcribed into Python, or vice-versa.

Requirements:

• Python 3.7 or above (tested on Windows, Linux and macOS).
• pyserial 2.6 or higher (pip install pyserial)
• Any Arduino compatible microcontroller with at least 14KB of flash memory

Installation + Setup

1. To install, run pip install pyArduinoAPI.

2. Load the prototype.ino sketch onto your Arduino board, using the Arduino IDE.

3. Set up some kind of serial I/O communication between the Arduino board and your computer (via physical USB cable, Bluetooth, xbee, etc. + associated drivers)

4. Add from Arduino import Arduino into your python script to communicate with your Arduino.

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What I've added so far that is different to the version I adapted this from:

• Added support for tone() and noTone() operations.
• Added (almost) complete support for the LiquidCrystal library for controlling LCD screens (missing write() and createChar() functions)

Examples

Simple usage example (LED blink):

from Arduino import Arduino
import time

board = Arduino()
board.pinMode(13, "OUTPUT")

while True:
    board.digitalWrite(13, "LOW")
    time.sleep(1)
    board.digitalWrite(13, "HIGH")
    time.sleep(1)

Python adaptation of Spaceship Interface:

from Arduino import Arduino
import time

board = Arduino()

switchState = 0

board.pinMode(3, "OUTPUT")
board.pinMode(4, "OUTPUT")
board.pinMode(5, "OUTPUT")
board.pinMode(2, "INPUT")

while True:
    switchState = board.digitalRead(2)

    if switchState == 0:
        board.digitalWrite(3, "HIGH")
        board.digitalWrite(4, "LOW")
        board.digitalWrite(5, "LOW")
    else:
        board.digitalWrite(3, "LOW")
        board.digitalWrite(4, "LOW")
        board.digitalWrite(5, "HIGH")

        time.sleep(0.25)
        board.digitalWrite(4, "HIGH")
        board.digitalWrite(5, "LOW")
        time.sleep(0.25)

Simple Servo Motor Control on pin 9:

from Arduino import Arduino
import time

board = Arduino()

board.Servos.attach(9)

while True:
    for pos in range(180):
        board.Servos.write(9, pos)
        time.sleep(0.015)

    for pos in range(180):
        pos = 180 - pos

        board.Servos.write(9, pos)
        time.sleep(0.015)

For a collection of examples, see examples.py. This file contains methods which replicate the functionality of many Arduino demo sketches.

Classes

• Arduino(baud) - Set up communication with currently connected and powered Arduino.

board = Arduino("115200") #Example

The device name / COM port of the connected Arduino will be auto-detected. If there are more than one Arduino boards connected, the desired COM port can be also be passed as an optional argument:

board = Arduino("115200", port="COM3") #Windows example

board = Arduino("115200", port="/dev/tty.usbmodemfa141") #OSX example

A time-out for reading from the Arduino can also be specified as an optional argument:

board = Arduino("115200", timeout=2) #Serial reading functions will
#wait for no more than 2 seconds

Methods

Digital I/O

• Arduino.digitalWrite(pin_number, state) turn digital pin on/off
• Arduino.digitalRead(pin_number) read state of a digital pin

#Digital read / write example
board.digitalWrite(13, "HIGH") #Set digital pin 13 voltage
state_1 = board.digitalRead(13) #Will return integer 1
board.digitalWrite(13, "LOW") #Set digital pin 13 voltage
state_2 = board.digitalRead(13) #Will return integer 0

• Arduino.pinMode(pin_number, io_mode) set pin I/O mode
• Arduino.pulseIn(pin_number, state) measures a pulse
• Arduino.pulseIn_set(pin_number, state) measures a pulse, with preconditioning

#Digital mode / pulse example
board.pinMode(7, "INPUT") #Set digital pin 7 mode to INPUT
duration = board.pulseIn(7, "HIGH") #Return pulse width measurement on pin 7

Analog I/O

• Arduino.analogRead(pin_number) returns the analog value
• Arduino.analogWrite(pin_number, value) sets the analog value

#Analog I/O examples
val=board.analogRead(5) #Read value on analog pin 5 (integer 0 to 1023)
val = val / 4 # scale to 0 - 255
board.analogWrite(11) #Set analog value (PWM) based on analog measurement

Shift Register

• Arduino.shiftIn(dataPin, clockPin, bitOrder) shift a byte in and returns it
• Arduino.shiftOut(dataPin, clockPin, bitOrder, value) shift the given byte out

bitOrder should be either "MSBFIRST" or "LSBFIRST"

Servo Library Functionality Support is included for up to 8 servos.

• Arduino.Servos.attach(pin, min=544, max=2400) Create servo instance. Only 8 servos can be used at one time.
• Arduino.Servos.read(pin) Returns the angle of the servo attached to the specified pin
• Arduino.Servos.write(pin, angle) Move an attached servo on a pin to a specified angle
• Arduino.Servos.writeMicroseconds(pin, uS) Write a value in microseconds to the servo on a specified pin
• Arduino.Servos.detach(pin) Detaches the servo on the specified pin

#Servo example
board.Servos.attach(9) #declare servo on pin 9
board.Servos.write(9, 0) #move servo on pin 9 to 0 degrees
print board.Servos.read(9) # should be 0
board.Servos.detach(9) #free pin 9

Software Serial Functionality

• Arduino.SoftwareSerial.begin(ss_rxPin, ss_txPin, ss_device_baud) initialize software serial device on specified pins. Only one software serial device can be used at a time. Existing software serial instance will be overwritten by calling this method, both in Python and on the Arduino board.
• Arduino.SoftwareSerial.write(data) send data using the Arduino 'write' function to the existing software serial connection.
• Arduino.SoftwareSerial.read() returns one byte from the existing software serial connection

#Software serial example
board.SoftwareSerial.begin(0, 7, "19200") # Start software serial for transmit only (tx on pin 7)
board.SoftwareSerial.write(" test ") #Send some data
response_char = board.SoftwareSerial.read() #read response character

EEPROM

• Arduino.EEPROM.read(address) reads a byte from the EEPROM
• Arduino.EEPROM.write(address, value) writes a byte to the EEPROM
• Arduino.EEPROM.size() returns size of the EEPROM

#EEPROM read and write examples
location = 42
value = 10 # 0-255(byte)

board.EEPROM.write(location, 10)
print(board.EEPROM.read(location))
print('EEPROM size {size}'.format(size=board.EEPROM.size()))

LCD Screen LiquidCrystal Support Library (only supports 1 display currently)

See https://www.arduino.cc/en/Reference/LiquidCrystal for reference to the LiquidCrystal library.

• Arduino.LCD.LiquidCrystal(rs, en, d4, d5, d6, d7) Creates an object of type LiquidCrystal.
• Arduino.LCD.begin(cols, rows) Initializes the interface to the LCD screen, and specifies the dimensions of the display.
• Arduino.LCD.cleanup() Deletes LCD object from Arduino system memory
• Arduino.LCD.clear() Clears the LCD screen and positions the cursor in the upper-left corner.
• Arduino.LCD.home() Positions the cursor in the upper-left corner of the LCD.
• Arduino.LCD.print(text) Prints text to the LCD screen.
• Arduino.LCD.setCursor(col, row) Sets the location at which subsequent text written to the LCD will be displayed.
• Arduino.LCD.cursor() Displays the LCD cursor.
• Arduino.LCD.noCursor() Hides the LCD cursor.
• Arduino.LCD.blink() Displays the blinking LCD cursor.
• Arduino.LCD.noBlink() Hides the blinking LCD cursor.
• Arduino.LCD.display() Turns the LCD display on.
• Arduino.LCD.noDisplay() Turns the LCD display off.
• Arduino.LCD.scrollDisplayLeft() Scrolls the contents of the display (text and cursor) one space to the left.
• Arduino.LCD.scrollDisplayRight() Scrolls the contents of the display (text and cursor) one space to the right.
• Arduino.LCD.autoscroll() Turns on automatic scrolling of the LCD.
• Arduino.LCD.noAutoscroll() Turns off automatic scrolling of the LCD.
• Arduino.LCD.leftToRight() Set the direction for text written to the LCD to left-to-right.
• Arduino.LCD.rightToLeft() Set the direction for text written to the LCD to right-to-left.

#LCD "Hello World" and time since start example
#Ported from https://www.arduino.cc/en/Tutorial/LibraryExamples/HelloWorld
import time
start_time = time.time()

board.LCD.LiquidCrystal(12, 11, 5, 4, 3, 2)
board.LCD.begin(16, 2)
board.LCD.print("hello, world!")

while True:
    board.LCD.setCursor(0, 1)

    board.LCD.print(round(time.time() - start_time))

Misc

• Arduino.resetFunc() Resets the Arduino.
• Arduino.close() Closes serial connection to the Arduino.

To-do list:

• Add simple reset functionality that zeros out all pin values
• Include a wizard which generates 'prototype.ino' with selected serial baud rate and Arduino function support (to help reduce memory requirements).
• Add write() and createChar() functions for the LCD library.
• Anything else that I come across that I need will be added here.