PyMata is a high performance, multi-threaded, non-blocking Python client for the Firmata Protocol that supports the complete StandardFirmata protocol.
###Major features
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Implements the entire Firmata 2.4.1 protocol.
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Python 2.7+ and Python 3.4+ compatibility through a shared code set. (If you are running Python 3.4 on Linux, please see note below).
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Easy to use and intuitive API. You can view the PyMata API Documentation here or view in the Documentation/html directory.
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Custom support for stepper motors, Sonar Ping Devices (HC-SRO4), Piezo devices and Rotary Encoders.
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Wiring diagrams are provided for all examples in the examples directory.
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Digial and Analog Transient Signal Monitoring Via Data Latches:
- They provide "one-shot" notification when either a digital or analog pin meets a user defined threshold.
- Analog latches compare each data change to a user specified value.
- Comparison operators are <, >, <= and >=
- Digital latches compare a data change to either a high or low, specified by the user.
- Latches can easily be re-armed to detect the next transient data change.
- Latches can be either manually read or a callback can be associated with a latch for immediate notification.
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Optional callbacks provide asynchronous notification of data updates: Check out the example code on the wiki
- Digital input pins.
- Analog input pins.
- Encoder changes.
- I2C read data changes.
- SONAR (HC-SR04) distance changes.
- Analog latch condition achieved.
- Digital latch condition achieved.
- Callbacks return data reports in a single list format.
- Polling methods and callbacks are available simultaneously and can be used in a mixed polled/callback environment.
- Callbacks return data in a single list.
###The callback data return values:
| Callback Type | List Element 0 | List Element 1 | List Element 2 | List Element 3 |
|---|---|---|---|---|
| Analog | ANALOG MODE | Pin Number | Data Value | Not Applicable |
| Digital | DIGITAL MODE | Pin Number | Data Value | Not Applicable |
| I2C | I2C MODE | I2C Device Address | Data Value | Not Applicable |
| Sonar | Trigger Pin | Distance in Centimeters | Not Applicable | Not Applicatble |
| Encoder | Encoder MODE | Pin Number | Data Value | Not Applicable |
| Latched Analog | LATCHED ANALOG MODE | Pin Number | Data Value | Time Stamp |
| Latched Digital | LATCHED DIGITAL MODE | Pin Number | Data Value | Time Stamp |
Below is a sample Control-C signal handler that can be added to a PyMata Application. It suppresses exceptions being reported as a result of the user entering a Control-C to abort the application.
import sys
import signal
# followed by another imports your application requires
# create a PyMata instance
# set the COM port string specifically for your platform
board = PyMata("/dev/ttyACM0")
# signal handler function called when Control-C occurs
def signal_handler(signal, frame):
print('You pressed Ctrl+C!!!!')
if board != None:
board.reset()
sys.exit(0)
# listen for SIGINT
signal.signal(signal.SIGINT, signal_handler)
# Your Application Continues Below This Point####Want to extend PyMata? See Our Instructables Article explaining how stepper motor support was added. Use it as a guide to customize PyMata for your own needs. ###Check Out Mr. Y's Blog Here for all the latest news!
##Special Note For Linux Users Wishing to Use Python 3.4 Python 3.4 (CPython) for Linux appears to run slower than Python 2.7. We will be investigating further and monitoring for a solution. The problem has been reported to python.org and may be tracked here: [http://bugs.python.org/issue23324] (http://bugs.python.org/issue23324)
A workaround is to use the PyPy interpreter
There are no performance issues between Python 2.7 and Python 3.4 when running Windows.