A High Performance Python Client For Arduino Firmata

MrYsLab, updated 🕥 2022-05-12 05:28:09


Please note that the pymata4 feature set is now frozen and the project has been placed in maintenance mode.

Please consider using Telemetrix instead.

A high performance, Python client for the Arduino Firmata Protocol.

Pymata4 is a Firmata client that, like its asyncio sibling, pymata-express, allows you to control an Arduino using the high-performance FirmataExpress sketch. It uses a conventional Python API for those that do not need or wish to use the asyncio programming paradigm of pymata-express.

A User's Guide is available, containing an annotated API as well as links to working examples.

It supports both an enhanced version of StandardaFirmata 2.5.8, called FirmataExpress, as well as StandardFirmata and StandardFimataWiFi.

  • FirmataExpress adds support for:
    • HC-SR04 Ultrasonic Distance Sensors.
    • DHT Humidity/Temperature Sensors.
    • Stepper Motors.
    • Piezo Tone Generation.
    • Baud rate of 115200

Special Note For FirmataExpress Users:

pymata4 now verifies the version of FirmataExpress in use. You may need to upgrade to the latest version of FirmataExpress using the Arduino IDE Library management tool.

Major features

  • Fully documented intuitive API

  • Python 3.7+ compatible.

  • Set the pin mode and go!

  • Data change events may be associated with a callback function, or each pin can be polled for its last event change.

    • Each data change event is time-stamped and logged.
  • User's Guide, Including Examples.

  • Implements 100% of the StandardFirmata Protocol (StandardFirmata 2.5.8).

  • Advanced auto-detection of Arduino devices (when using FirmataExpress).

Here is an example that monitors data changes on a digital input pin. It demonstrates both callback and polling techniques

```python import time import sys from pymata4 import pymata4

""" Setup a pin for digital input and monitor its changes Both polling and callback are being used in this example. """

Setup a pin for analog input and monitor its changes

DIGITAL_PIN = 12 # arduino pin number POLL_TIME = 5 # number of seconds between polls

Callback data indices

Callback data indices


def the_callback(data): """ A callback function to report data changes. This will print the pin number, its reported value and the date and time when the change occurred

:param data: [pin, current reported value, pin_mode, timestamp]
date = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(data[CB_TIME]))
print(f'Pin: {data[CB_PIN]} Value: {data[CB_VALUE]} Time Stamp: {date}')

def digital_in(my_board, pin): """ This function establishes the pin as a digital input. Any changes on this pin will be reported through the call back function.

 :param my_board: a pymata_express instance
 :param pin: Arduino pin number

# set the pin mode
my_board.set_pin_mode_digital_input(pin, callback=the_callback)

while True:
        # Do a read of the last value reported every 5 seconds and print it
        # digital_read returns A tuple of last value change and the time that it occurred
        value, time_stamp = my_board.digital_read(pin)
        date = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time_stamp))
        # value
        print(f'Polling - last value: {value} received on {date} ')
    except KeyboardInterrupt:

board = pymata4.Pymata4()

try: digital_in(board, DIGITAL_PIN) except KeyboardInterrupt: board.shutdown() sys.exit(0)


And here is the console output: ```bash pymata4: Version 1.00

Copyright (c) 2020 Alan Yorinks All Rights Reserved.

Opening all potential serial ports... /dev/ttyACM0

Waiting 4 seconds(arduino_wait) for Arduino devices to reset...

Searching for an Arduino configured with an arduino_instance = 1 Arduino compatible device found and connected to /dev/ttyACM0

Retrieving Arduino Firmware ID... Arduino Firmware ID: 2.5 FirmataExpress.ino

Retrieving analog map... Auto-discovery complete. Found 20 Digital Pins and 6 Analog Pins

Polling - last change: 0 change received on 1969-12-31 19:00:00 Pin: 12 Value: 0 Time Stamp: 2020-03-07 08:52:10 Pin: 12 Value: 1 Time Stamp: 2020-03-07 08:52:12 Polling - last value: 1 received on 2020-03-07 08:52:12 ```

This project was developed with Pycharm logo


Fixes issue #44 2022-01-21 20:36:10

2021-11-10 19:01:35

Additional fixes for issue #39 2021-11-02 17:11:36

Addresses issue #39 2021-10-29 15:49:55

Incorporated DHTStable for DHT support 2021-05-30 13:46:08

Only the DHT support code changed. This change requires the use of FirmataExpress version 1.2.0

Add DHT to capability report 2020-06-29 14:30:04

To enable this feature, FirmataExpress 1.1.2 or later must be used.

Alan Yorinks
GitHub Repository

python arduino-firmata