This is the next evolution of the original $5 Mobile/Accessory/Multifunction 17 Channel Configurable DCC Decoder. This edition: 1.expands major functionality to drive a stepper motor , d ual motor control with sound , and even triggered sounds (like a driver cam), servos , and LEDs with 17 function pins, 2.implements long DCC addresses for both mobile decoders and accessory decoders, and 3.and now uses the updated NmraDcc library compatible with the ATTiny84/85 and Teensy 3.x processors. 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 UPDATED: August 7, 2018 . 7th Decoder Pin Function added Jan 20, 2020 https://forum.mrhmag.com/post/sma20-low-cost-17-channel-dcc-decoders-ver-6-01-with-soundtriggered-soundstepperdual-motorled-and-12201920 Increased power and other enhancements described here: SMA34 More Power to SMA20 Decoders with Tips and Additions https://forum.mrhmag.com/post/sma34-more-power-to-sma20-decoders-with-tips-and-additions-12215355 📷