Decoder to control an elevator (lift) for model trains. The print includes two micro controllers. The ATMEGA 328 is used to control two stepper motor drivers (X and Y = left and right). Software is intended to be [GRBL](https://github.com/gnea/grbl/wiki). Limit switches can be connected via two [opto-couplers](https://github.com/gnea/grbl/wiki/Wiring-Limit-Switches). The ATMEGA 2560 is the main processor that: - Sends commands to the GRBL ATMEGA 328 - Receives [DCC](https://en.wikipedia.org/wiki/Digital_Command_Control) commands from a DCC master station - Sends feedback messages via the [RS-Bus](https://sites.google.com/site/dcctrains/rs-bus-feed) to the master station - Has 14 digital inputs for buttons and/or IR receivers (light barriers) - Has 14 digital outputs for LEDs and/or IR transmitters (light barriers) To offload the ATMEGA 2560, the software can be split over multiple PCBs. Communication between the PCBs takes place via a RS485 bus. Only 1 of the PCBs need to receive external power (AC 12-18V), the others may receive power from the main PCB. Costs for 5 PCBs with all SMD components assembled is around 100 Euro (including tax and shipping). Costs do not include the Through-hole components, such as jumpers and terminals. - Updated 2020/07/14: PAD spacing SS34 reduced