Open Source DCC Locomotive Decoder V2.0

The OpenDec02 DCC Decoder harnesses the power of Raspberry Pi’s RP2040 microcontroller, bringing a new level of precision, flexibility, and innovation to model railroading. This cutting-edge decoder is built on an open-source platform, designed for hobbyists who demand the ability to customize, enhance, and evolve their model railroad systems.

We’re now introducing Version 2.0 – enhanced for greater usability and effortless firmware updates. Now it’s easier than ever to tinker with new features and customize how it works to suit your needs. We’ve also replaced the old linear voltage regulator, which would become super hot during operation, with a switched 3.3V regulator that helps to keep the board cool.

The OpenDec02 DCC Decoder stands out by offering an unparalleled blend of performance, customization, and community support. Whether you’re a seasoned hobbyist or new to model railroading, the OpenDec02 provides a robust platform for innovation. Embrace the future of model railroading with the OpenDec02, where your creativity and technical skills can truly flourish.

The OpenDec02 board is based on Gabriel Koppenstein’s open-source project found here. All kudos for this project goes to Gabriel, the only thing iLabs have added is an optimised layout and their knowledge in production. His GitHub pages describe the architecture and how to work with the device in a very clear manner.

Features

• Microcontroller: RP2040 by the Raspberry Pi
• Compatibility: Fully compatible with DCC standards
• Programming: Open-source software built on top of Raspberry Pi’s C-SDK
• Motor Control: Advanced PID control for maintaining speed under different loads as well as smooth acceleration and deceleration
• Sound and Lighting: Programmable outputs for realistic lighting effects
• Sound: Not yet, but with direct access to a number of GPIO’s and the source code anyone can have a stab at it
• Connectivity: Supports additional sensors and actuators for extended functionality
• Community: Access to a vibrant community for support, ideas, and collaboration

Specifications

• Memory: 264KB of SRAM, and 8MB of onboard Flash memory
• Core: Dual-core ARM Cortex-M0+ processor, up to 133 MHz, overclockable (how is that even a word) to 250MHz
• Input/Output: 6 Digital I/O logic IO signals and 4 30V/450mA outputs
• Communication: UART, I2C, SPI can be configured for communication with external devices
• Dimensions: Compact form factor (20x25mm) for easy integration into model locomotives
• Motor current: 2.0A max continuous, with motor driver mounted to chassis
• PCB:
  • 4-layer board with solid ground plane for improved heat distribution 
  • Big solder pads for easy soldering of wires to the PCB

Changes between version 1.0 and 2.0

• The pads for the USB signals have been removed
• The linear regulator has been replaced with a switched regulator
• A new 4-pin debug connector has been added to the system
• The faulty ABC support has been corrected in this design

Benefits

• Customisation: Tailor every aspect of your model locomotive by modifying the source code.
• Performance: Leverage the RP2040’s high performance for sophisticated control schemes.
• Community Support: Benefit from the knowledge and creativity of the open-source community.
• Future-Proof: Continuously upgradeable with the latest features and improvements.

Firmware and new debugger interface

The device is flashed with the latest available firmware at the time of shipping, so if you are just aiming to run the decoder you can do so.

If you want to update your device or if you want to start tinkering yourself with changing the source code we have included a new super small programming/debug connector on the board. This new connector follows the BConnect (BSWD) specification that allows you to flash and debug the onboard RP2040, as well as send UART data to the debugger device, all over one very small 4 lead Flat Flexible Cable (FFC).

We stock the iLabs iProbe board precisely for this purpose.

Resources

• Gabriel’s excellent architectural documents
• Schematic for version 1.0
• Schematic for version 2.0
• Software repository (Github)
• Product number: iLabs 98-00299-1

Package Contents

• 1x Open Source DCC Locomotive Decoder V2.0