The SMA20 New Low Cost 17 Channel DCC Decoders & Dual Motor,LED, & Servo Control Updated: 6 Ftns/Pin & New Features
is a Geoff Bunza Design. Geoff published this in his column in MRH as SMA20 and documentation can be found in the article. Geoff provides design information including Gerber files, so you can easily have your own boards made, but we keep bare boards in stock and sell them in quantities as small as one, where economic orders at the board vendors usually require the purchase of several boards.
Geoff says :
"This is the next evolution of the original $5 Mobile/Accessory/Multifunction 17 Channel Configurable DCC Decoder. This edition: 1. consolidates much of the information previously spread in multiple blogs, including consolidating the library of 20 examples ready for modelers to download and use, 2. introduces the availability of small “daughter” printed circuit boards for the Pro Mini controller to ease construction for all decoder versions, and 3. adds decoder functionality that enables control of two small motors! As before, the functions per pin are reconfigurable via CV control. The PC Boards described here can also be used as an add-on daughter board, or in Arduino terms a “shield” for the Pro Mini, including non-decoder projects. NEW Library UPDATE: August 11, 2016"
If you use your DCC bus as your layout control bus this is a very handy (and really cost effective!) board. Check it out!