The only constraint initially set in the specifications was to produce the smallest, simplest DCC unit possible, with all the functions of a large one.

Here are the choices made during the design of these assemblies, and the arguments that led to this solution:

• A single traction track: the duration of use of a programming track is very low compared to the duration of operation. It's a waste of resources to have a power circuit with current measurement that's practically never used. It's better to be able to select the operating mode, so that you can still set the parameters for your locomotives.
• Do not use a commercially available power module that has already been assembled: commercial L298N-based modules contain a lot of bulky components that are also unnecessary for this project: 5 V power supply, terminal blocks, smoothing capacitors, jumpers, etc.
• Do not use MAX47X-based modules to measure current consumption: in addition to being prone to failure, these small commercial modules have a significant impact on the circuit, due to the high value of the resistor used for measurement. Current consumption will be monitored using an op-amp-based circuit.
• Use an Arduino Nano board to generate the DCC signal: to save space for the microcontroller, the DCC++ program will have to be adapted for use with the Nano. This operation (already carried out by a modeler on the Locoduino website) simply involves replacing the Arduino Uno references in the program with those of the Nano.
• To be able to control a number of motors without having to type in codes to access functions, and to avoid using a keyboard as much as possible.