MM2

MM2 is an implementation of the Motorola 1 and 2 (MM1/2) protocol. Details on the format can be found on Dr. König's Märklin-Digital-Page or in the docs folder in case this site goes offline. This library supports MM1 and 2 as well as some additions like CV programming and follow-up addresses for supporting more than 5 functions.

Examples

Currently there is only one class for receiving MM2.

• mm2::rx::CrtpBase

As the names suggest this class relies on CRTP to implement static polymorphism. The template argument of the base classes is checked with a concept called Decoder.

Here is an example for how a class which implements it might look. The friend declarations are only necessary if the methods the base(s) need to call are not public.

#include <mm2/mm2.hpp>

struct Mm2 : mm2::rx::CrtpBase<Mm2> {
  friend mm2::rx::CrtpBase<Mm2>;

private:
  // Set direction (1 forward, 0 backward)
  void direction(uint32_t addr, bool dir) {}

  // Set speed [0, 255] (regardless of CV settings)
  void speed(uint32_t addr, int32_t speed) {}

  // Reverse direction
  void reverse(uint32_t addr) {}

  // Set function inputs
  void function(uint32_t addr, uint32_t mask, uint32_t state) {}

  // Read CV
  uint8_t readCv(uint32_t cv_addr) {}

  // Write CV
  uint8_t writeCv(uint32_t cv_addr, uint8_t value) {}

  // Timer interrupt calls receive with captured value
  void interrupt() {
    uint32_t const timer_value{/* captured timer value */};
    receive(timer_value);
  }
};