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quote:

Originally posted by DaveJfr0:
Does anyone here know of a good resource to learning how to build a DCC Decoder?
I am mainly wanting to learn the basics of how the codes are decoded (ie - what chips, etc. are needed). I am not looking to learn how to drive motors, but perhaps taking in commands, processing them, and sending out my own little signals…ie simple things like turning on and off an LED.

I have a few questions; please do not take them as offensive..........
Do you have an excellent comprrehension of electronics?
Do you have an excellent comprehension of software, assembly e.g.?
Are you doing this for fun? to save money? or to make money?

DCC, DCS, and TMCC are not elegantly simple.

Regards,
Lou N

OpenDCC decoder has schematics and open source downloadable code for accessory decoders with varying levels of sophistication. Here's a pix of the basic accessory decoder based on a $2 Atmel microprocessor.

Particularly for layout accessories (vs. engines) is the ability to build a decoder for a few bucks. The cost of demodulating DCC is negligible (vs. TMCC or DCS). A possible mid-ground, to bypass the nerdy factor, would be for someone to develop and sell pre-programmed microcontrollers that had DCC decoding built-in. For about $1 in small quantities, microcontrollers with a handful of outputs have 1% internal oscillator (so no crystal needed) and internal EEROM. CVs would be used to configure the output functions from a library of capabilities stored in the chip. It then becomes a hardware-only pursuit which makes it palatable to a much broader audience. The chip could be used in a non-DCC environment as it only needs to be configured using DCC. Perhaps such a chip already exists.

quote:

Originally posted by DaveJfr0:
I know it won't be easy, but I'd be interested in getting my feet wet. I do not care about the DCS signal, mainly DCC and probably some TMCC.

Just some passing thoughts - you can make any of the above for yourself. DCS and TMCC are covered by patents and only TMCC was licensed, so they can't be for resale.

Good luck with your project.

Lou N

David, thanks for you blog. It is a good read.

So, DCC is an open standard, right? Everything is here:

http://www.nmra.org/standards/...rds_rps/DCCStds.html

Sounds like S-9.1, S-9.2, and RP-9.2.1 are the most relevant.

Has anyone ever begun work on a C library that would compile on various microcontrollers? David, if such a library were licensed BSD or Apache, would you use it (or even contribute to it)? It would work with commercial software.

I am terribly ignorant when it comes to electronics and DCC, but that has never stopped me before. I am not a brilliant C programmer, but I really enjoy it.

Lou asks great questions. For me, this kind of thing has a "because it's there" attraction. I want to learn more about electronics and microcontrollers (PIC or Atmel AVR), but I need a reason. DCC could be it. I'll see if the interest blossoms into anything more in the next few years.

Thanks so much for this discussion!

Regards,
Jonathan

quote:

Originally posted by Jonathan Bowman:
I want to learn more about electronics and microcontrollers (PIC or Atmel AVR), but I need a reason. DCC could be it. I'll see if the interest blossoms into anything more in the next few years.

Thanks so much for this discussion!

Regards,
Jonathan

Check with your local electronics distributor; find one that sells MicroChip. They usually sponsor PIC classes where you get training, a PICstart Programmer and a sample PIC IC for around fifty bucks.

Lou N