dcc-rs

Pure-Rust implementation of NMRA Digital Command Control

This crate implements the NMRA DCC protocol, intended for embedded use on e.g. custom base stations for computer control. It is fully no_std-compatible, with zero allocations and uses the embedded_hal traits for driving output pins.

To work around the lack of standardised interrupt support, this crate provides a DccInterruptHandler struct which may be owned by a static within an interrupt handler, and the DccInterruptHandler::tick method performs all of the necessary processing, returning the number of microseconds to wait before it should be called again. This timing is critical to the correct functioning of this crate as it is used to time the output pin transitions.

Getting new data packets into the DccInterruptHandler is left as an exercise for the implementor. In the provided example code, it is done via a Mutex holding a RefCell<Option<_>>, which allows external code to pop new serialised packets in for the interrupt handler to retrieve at its leisure.

Status

This crate currently only implements the base station (transmitter) side, and only the "baseline" and "service mode" packets. "Extended format" DCC packets are a work in progress.

DCC receiving is under future work, once the main packet types have been implemented.

Example implementations

• examples/stm32f103-blue-pill Single-channel speed controller

Contributing

Contributions are welcome, in the form of code improvements, testing reports, more example implementations, more platform implementations, etc. I'm particularly interested in getting this running on an arduino uno/nano once the loose ends in Rust's AVR support have been tidied up. A drop-in replacement DCC++-compatible firmware would also be neat.

Licence

This crate is available under the terms of the Mozilla Public Licence Version 2.0.