Introduction

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DMX512 lighting protocol transmitter on the RP2040

Usage Example

.. code-block:: Python

"Blink a DMX-equipped light."

import time
import board

from dmx_transmitter import dmx_transmitter

# Wire DMX_PIN to an isolated RS485 line driver.

DMX_PIN = board.D0

dmx = dmx_transmitter.DMXTransmitter(first_out_pin=DMX_PIN)

# Blinking lights
while True:
    dmx.clear()  # Turn off the light(s)
    dmx.show()
    time.sleep(1)
    dmx[0:3] = 255  # Turn lights on full. DMX channels: 1, 2, 3,
    dmx.show()
    time.sleep(1)

# Note: The dmx index numbers are one (1) less than the DMX channel
#       number. This is by design.

Schematic

Example::

     ┌─────┐            ╔═════════════════╗
╔════╡USB-C╞════╗       ║                 ║
║    └─────┘    ║    ┌──╫(6) VCC          ║       ╔══════════════╗  
║            3V ╫────┤  ║    __         Y ╫───────╫─< (3) Data + ║
║               ║    ├──╫(1) RE           ║  ┌────╫─< (2) Data - ║
║               ║    │  ║               Z ╫──┘ ┌──╫─< (1) Common ║
║               ║    └──╫(4) DE           ║    │  ╚══════════════╝
║         TX/DO ╫───┐   ║               A ╫ NC │   XLR Connector
║               ║   └───╫(2) TXD          ║    │   Female
║               ║       ║               B ╫ NC │
║               ║    NC ╫(3) RXD          ║    │
║           GND ╫──┐    ║          ISOGND ╫────┴────┐
║               ║  └────╫(5) GND          ║      ┌──┴───┐
║               ║       ║                 ║      │Earth │
╚═══════════════╝       ╚═════════════════╝      │Ground│
 Microcontroller         RS485 Line Driver       └──────┘
 Adafruit KB2040         Digilent PmodR485

Significant DMX wiring requirements are necessarily out of scope
in this document. Consult a qualified local expert.

REQUIREMENTS

Hardware:

• Any RP2040 CircuitPython board. I used the Adafruit KB2040 <https://www.adafruit.com/product/5302>_ (Product ID: <5302>)

• An isolated RS485 line driver. I used a Digilent PmodRS485.

Software and Dependencies:

• Adafruit CircuitPython <https://github.com/adafruit/circuitpython>_

• This library, dmx_transmitter, especially these files::

  • dmx_transmitter.mpy
  • payload_USITT_DMX512_A.mpy

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle <https://circuitpython.org/libraries> or individual libraries can be installed using circup <https://github.com/adafruit/circup>.

Installing to a Connected CircuitPython Device with Circup

Make sure that you have circup installed in your Python environment. Install it with the following command if necessary:

.. code-block:: shell

pip3 install circup

With circup installed and your CircuitPython device connected use the following command to install:

.. code-block:: shell

circup install dmx_transmitter

Or the following command to update an existing version:

.. code-block:: shell

circup update

Documentation

API documentation for this library can be found on Read the Docs <https://circuitpython-dmx-transmitter.readthedocs.io/>_.

For information on building library documentation, please check out this guide <https://learn.adafruit.com/creating-and-sharing-a-circuitpython-library/sharing-our-docs-on-readthedocs#sphinx-5-1>_.

Contributing

Contributions are welcome! Please read our Code of Conduct <https://github.com/mydana/CircuitPython_DMX_Transmitter/blob/HEAD/CODE_OF_CONDUCT.md>_ before contributing to help this project stay welcoming.