SMA10 – Build a 17-Function DCC Decoder for about $5

geoffb's picture

My activities in Scale Model Animation often lead me to use DCC as a control method for sequencing. This could include building and street lights, even sparking welders and twinkling camp fires. Timing can be done with JMRI scripts (Like this: http://youtu.be/RXpvp5mIXvU?list=PL4dHfZjHc9t-pvctGQzSuOXBLG1M42xbS) or with programmatic control (Like this: http://youtu.be/zlcdJKXj_YI?list=PL4dHfZjHc9t-pvctGQzSuOXBLG1M42xbS). Control switches for such projects are a must. Using 4 or 6 function DCC decoders in this regard, can get costly, quickly. But with a little effort, and some low cost components one can build a DCC decoder supporting 17 independent functions for about $5.00, or less, depending what you have on hand.  This version has no CV’s, uses no DCC programming, can be set for any short address in CV1, and controls 17 Function Lines (which I am using to drive the green LEDs in the example below). Interested? Read on! (Latest Rev for this work can be found here: http://model-railroad-hobbyist.com/node/19446 )

Comments

Thanks for introducing this decoder

Wow, its been awhile since I programmed a controller, great  idea and price.

Had a flashback when I looked at the specs to the early nineties and a 80C186EA based bored with 32KB eeprom and battery backed up static ram. However, it cost a lot more and had a footprint, literally.

My question and concern is should the DCC bus be used for an ever increasing load of fixed animations? Could there be a risk of fire if an , for example, 8 amp DCC booster is installed?

 

Eugene

 

I wonder if a version of this

I wonder if a version of this could be made smaller to fit inside N scale locos as an alternative to other decoders?

geoffb's picture

DCC Bus Load

Hi Eugene,

My question and concern is should the DCC bus be used for an ever increasing load of fixed animations? Could there be a risk of fire if an , for example, 8 amp DCC booster is installed?

This decoder loads the DCC bus just like any other decoder with a load. Put enough decoders on any DCC bus and eventually you run out of power. As from my comments above, I intend to run some of my animations and lighting on separate DCC lines apart from the track DCC, and I'll still need to keep track of power utilization.

Best Regards,

Geoff Bunza

 

 

geoffb's picture

N Scale??

Hi,

I wonder if a version of this could be made smaller to fit inside N scale locos as an alternative to other decoders?

This was never intended to be optimized for size-- low cost and many modifiable features were my goals. Nonetheless, a 17-function-only DCC decoder suitable for an N scale loco might be a challenge just based on the bulk of the wires and connections!! Might you have an application in mind that is not obvious to me? It could be interesting, but in my applications this is actually quite small enough, especially when you consider that all the LEDs would not be mounted on the board. Thought provoking, though. Thanks for sharing your idea.

Best regards,

Geoff Bunza

 

 

geoffb's picture

@Paul -- Current Sourcing

Hi Paul,

I take it that this module would have little issue to sink current for a turnout servo; I'm thinking it could adequately source it too? My Uno has the ability to do the latter.

A servo is usually looking for a current source, but the little Pro Mini has the same 328P chip most versions of the Uno have! So it will source and sink current on demand. The small servos present little load comparatively, so you can drive them directly off a naked pin on either the Pro Mini or the Uno and there are several libraries available to help with servo control. I hope to add a CV controlled option eventually to configure each pin. I'm hoping to make servo control such a feature-- lots to do, but fun to look forward to! smiley

Best regards,

Geoff Bunza

 

 

 

Brentglen's picture

Thanks for Posting this

Thanks for posting this. I did buy an Arduino starter kit but haven't done much with it. This should motivate me to learn more about it.

 

 

Brent Ciccone

Calgary

Bernd's picture

Very Interesting

Geoff,

Very interesting write up Geoff. Following along and getting ideas for animations I'd like to try out. It's inspiring me to get get going on a layout. smiley But I'll wait till you have it all together and I have something that resembles a layout. Still thinking an animated rock crusher loading HOn30 cars and an animated coal mine operation loading HOn3 hoppers automatically.

Carry on.

Bernd

 

New York, Vermont & Northern Rwy. - Route of the Black Diamonds     

geoffb's picture

@Brent-- Starting Up

Hi Brent,

If you get to some non-obvious roadblock... ask questions. Most of the basics are straightforward. You'll complicate things later when you start wanting to do more and more!  smiley

And then you may find out.... it CAN be done!

Have fun!

Best regards,

Geoff

 

 

geoffb's picture

@Bernd-- More to Come

Hi Bernd,

Interesting indeed... I model with HOn30 too, and am trying to work into a dual guage scene (animated of course!).

Best Regards,

Geoff

 

Michael T.'s picture

I'm good with the hardware end....

I'm a ham radio operator and have built many a circuit over the years including a 50 watt RF amplifier using 1205 size SMD's hand soldered to the board so I'm good with the hardware end. I also know my way around a PC pretty well but beyond that, the software and programming end of these little devices is greek to me. I built an antenna rotator positioning control box that was designed around a BASIC STAMP but the program to run it was pre-written and I merely had to load it into the stamp. Low cost DIY hardware does interest me though so I guess I should find the time to learn a little more about the programming end.

Michael

 

Michael

Original member of the "Gang of Six"

R.I.P. Verne Niner. The time I got to know you was way too short my friend.

"We all model the prototype, to suggest otherwise is ridiculous"

My Pike, https://mrhmag.com/blog/MichaelT

 


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