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USB Configurable Arduino DDC Servo & Accessory Decoder – ArCoMoRa 2 – Configure an On Off Accessory

USB Configurable Arduino DDC Servo & Accessory Decoder – ArCoMoRa 2 – Configure an On Off Accessory

Now that we installed the Windows software (see previous video) and uploaded the MARDEC sketch to a DCCnext or to an Arduino, we can start to configure the 16 available ports to do what we want them to do.

The video shows an example of how to configure an on/off accessory on port 1 that switches via DCC address 8.

The next vodeo will show a double flashing light and control of a solenoid junction with a double one shot.

Read on below the video …



MARDEC has two modes of operation:

  • Configuration mode is where we enter commands to match output ports with DCC addresses and enter all the parameters needed with that output, like the accessory type or the servo min/max angles. The Arduino is connected to our PC or laptop via USB. When we enter the E (Exit) command , we switch to normal mode.
  • Normal operation mode is where the output ports are controlled via DCC addresses. USB connection is not needed in this mode. If we want to change the configuration we can reconnect USB and enter the C (Config) command to switch to config mode.


To configure a port as an accessory, follow these steps:

  1. If in Normal mode, type C to enter Config mode
  2. Type P and enter the port number we connected the accessory to
  3. Enter the DCC address we want this accessory to have
  4. Type 1 to make this port an Accessory
  5. Type M and enter the mode we want this port to have (see list below)
  6. Enter additional parameters if asked
  7. Type Enter to exit and store this port configuration
  8. Type P to configure another port, or …
  9. Type E to exit config mode and enter normal DCC operation mode

The following accessory modes are available:

  1. steady on / off, single port
  2. steady on / off, with an inverted buddy port
  3. one shot pulse, single port
  4. one shot pulse, with a buddy port, e.g. to switch solenoid junctions
  5. flash with separate on- and off times, single port
  6. flash, with an inverted buddy port
  7. PWM (analog) output, with a fade in and fade out
  8. flicker (uses PWM)
  9. random flash (seconds)
  10. random flash (milliseconds)


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Welcome at this website / blog

This website / blog contains all kinds of info on the model railway hobby project I'm working on.

This homepage is where new posts appear when a major step has been made, or when I came across something noteworthy.

The other pages in the topmenu and the sidebar store information to be easily found back.

The railway hobby to me is more about electronics and (micro) computer control than about scenery. A lot can be found here on the use of Arduino as a DCC decoder and on Traincontroller PC layout control.

Who knows these pages may be helpful not only to myself, but also to other model train hobbyists..

There's also a Youtube Channel.