DCC-EX Releases 5A EX-MotorShield8874

DCC-EX, a global contributor to DCC open source software for model railroading, is proud to announce the first of our open source hardware products: the EX-MotorShield8874 providing dual 5 amp DCC and DC PWM (pulse width modulation) output for DCC-EX Command Stations.

The EX-MotorShield8874 addresses the needs of DCC-EX users wanting to run multiple locos, across multiple power districts without requiring expensive DCC boosters. A DCC-EX Command Station can now outperform commercial DCC command stations which typically have single 3-3.5A or 5A output capabilities, and doing so at a fraction of the cost and with more advanced features.

The EX-MotorShield8874 is the first offering in the DCC-EX open source hardware ecosystem specifically designed for model railroaders, and is a direct result of the strong community engagement DCC-EX strives to inspire. DCC-EX hardware lead Paul Antoine says “the open source vision for hardware designs from the DCC-EX community means individual users can order small batch manufacturing of all DCC-EX endorsed designs for themselves, friends and fellow club members. Or they have the choice to buy the same quality of product from licensed local resellers in their countries of origin.”

DCC-EX EX-MotorShield8874 RevA Semify

Featuring dual 5A output Texas Instruments DRV8874 MOSFET H-Bridge ICs, the EX-MotorShield8874 shield is fully drop-in compatible with the industry standard Arduino Motor Shield R3 due to additional logic onboard, along with plenty of new features. As a result, it can immediately replace older L298 based boards without software modifications. There is no need to have to cut traces or bend out pins, and the EX-MotorShield8874 can power your EX-CommmandStation too! The DRV8874 H-Bridge ICs also include hardware overcurrent protection monitored by EX-CommandStation, in addition to the existing software-based overload protection.

DCC-EX specific features include single 2.1mm barrel jack DC power for both the DCC/DC output and to supply the underlying Command Station motherboard with inbuilt polarity protection. This eliminates the need for a separate power supply for the Command Station motherboard. An onboard switching power supply regulates the DCC track input voltage to a safe 7.2VDC to the motherboard via the VIN pin, ensuring its linear 5V and 3.3V regulators stay as cool as possible.

EX-MotorShield8874 is also future-proof, being compatible with current Arduino UNO and Mega based DCC-EX command station motherboards, and the more powerful platforms under development which use 3.3V microcontrollers, such as STM32 Nucleo and ESP32 based designs.

EX-MotorShield8874 sports I2C support via an industry standard STEMMA QT/Qwiic connectors and pin headers making I2C bus connections easier than ever. The STEMMA QT/Qwiic ecosystem of I2C boards from Adafruit and Sparkfun are now the easiest I2C expansion boards to use. The DCC-EX team expects to add additional STEMMA QT/Qwiic based peripherals with model railroading friendly features in upcoming releases. An I2C SIP header is included to allow many I2C enabled OLED screens to plug directly into the board.

The design of the EX-MotorShield8874 was Inspired by a discussion on the Austrian 1zu160 N scale model railway forum between DCC-EX development team member Harald Barth and enthusiastic DCC-EX user Erwin Peterlin. Erwin then designed the prototype EX-MotorShield8874 in a matter of days. Erwin is a skilled Digital Design and Verification Engineer by day for his employer, Semify (semify-eda.com) of Austria, who kindly offered to fund the prototype boards. Semify has also arranged to sell their initial production test batch on Tindie.

Erwin worked closely with the DCC-EX team on specification of additional features to suit DCC-EX software, with early prototypes being provided to the DCC-EX team for testing and verification. We are proud to say that Erwin opted to become part of the DCC-EX team and will continue to work on future projects.

Erwin and Semify have graciously provided the design files for the EX-MotorShield8874 on an open source basis, allowing DCC-EX users to order small batches of up to 10 assembled units from manufacturers such as JLCPCB.

Entrepreneurs wanting to offer commercial quantities to their local communities should contact Semify (service @ semify-eda.com) to arrange a bulk purchase, or DCC-EX (support @ dcc-ex.com) when looking to use the design to manufacture. Licensing includes donating a royalty to DCC-EX per board sold. Semify has a separate arrangement with DCC-EX due to their funding of the prototyping and work on verifying and testing the design.

EX-MotorShield8874 is available immediately for purchase in the EU, USA and Canada via Semify’s Tindie store (https://www.tindie.com/products/semify/semify-dcc-ex-motor-shield/) starting at $US34.90 each, and in Australia, New Zealand and South East Asia from Millennium Engineering Pty Ltd (orders @ milleng.com.au) for $AU55, plus shipping. It will also be available shortly in the UK through Chesterfield Model Making & Miniature Electronics (https://chesterfield-models.co.uk/product/semify-dcc-ex-motor-shield/), for £29.99 plus shipping. Expect further announcements re local availability in the US through DCC-EX directly and Smart Hobby LLC, with other countries to follow.

Design files and initial hardware documentation are at: https://github.com/DCC-EX/EX-Hardware/tree/main/EX-Motorshield8874 and installation details at: https://dcc-ex.com/reference/hardware/motorboards/ex-motor-shield-8874.html

DCC-EX Website will have further documentation for the EX-MotorShield8874, and extended support in software will be included in the upcoming EX-CommandStation v5.0 release scheduled for late May 2023.