Introduction

DMX512 lighting protocol transmitter on the RP2040

Usage Example

"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 (Product ID: <5302>)
• An isolated RS485 line driver. I used a Digilent PmodRS485.

Software and Dependencies:

• 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 or individual libraries can be installed using 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:

pip3 install circup

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

circup install dmx_transmitter

Or the following command to update an existing version:

circup update

Documentation

API documentation for this library can be found on Read the Docs.

For information on building library documentation, please check out this guide.

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.