home built mini-dcc

Is anyone using a mini-DCC or other home built system?
I've started building a mini-dcc type system to replace my Bachmann EZ
Command controller that doesn't really seem to be working right anyway. I'll explain more on that at the end of the post.
I got the PIC-board/keypad/LCD display portion done yesterday and the software seems to be working fine. :-) The display is working and the buttons seem to do what they are supposed to. I still need to solder up the power part (H-bridge) and the safety stuff (emergency stop, DCC presence/short-circuit detection etc). I'm using an LMD18200, so I should be able to supply up to 3A to the track. I'm sorta copying this persons implementation: http://home.cogeco.ca/~rpaisley4/MyDCC.html My plans are to eventually replace the PIC with an ARM processor, and add more functionality such as ack-detection and two-way communications of some sort.
Any advice or comments?
Bachmann EZ Command Woes: The Bachmann controller I have refuses to send a speed setting of 0 to any engine. As if it doesn't think I've turned the speed knob far enough to the left. :-/ It worked ok when it was new, but after a few days it started acting up. At first it was intermittent and now it's a full time thing with new symptoms developing. It's really annoying, you can't stop any of the engines once you move them. They just creep around at speed step 1.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Anthony Fremont schrieb am 02.01.2008 15:43:

Why don't you get the EZ Command repaired? You describe a defect to be fixed but no design limitation to be solved by a home grown controller.
--
mit freundlichen Gruessen Reinhard Peters

mail: snipped-for-privacy@rub-peters.de
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Reinhard Peters wrote:

I intend to get it fixed and keep as a backup, but what would I use while it is mailed to Bachmann? The biggest design limitations of the EZ Command are that it can't program any CVs other than the locomotive short address and the default direction. Other limitations include lower output power, only 28 speed steps, no accessory power output etc....
thanks for the reply :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sounds like you might need a better system altogether. Use the Bachmann EZ-DCC system for your test track, and get something better for your layout. Digitrax systems cost about $150 (minimum) and are expandable.
I am interested in building your own DCC system, though...
Puckdropper
--
Marching to the beat of a different drum is great... unless you're in
marching band.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Puckdropper wrote:

That's what I'm hoping to end up with.....eventually. ;-)

That's what I was thinking.

And that's the main problem. I'm too cheap to shell out for the Zephyr system, much less the $400 that one giving me the control I'd really like. I only have about $50 tied up in this project so far, but I have a pretty good collection of parts in my "junkbox". The most expensive piece is the h-bridge, and it goes for $14 at Digikey, the breakout pc board is available from www.sparkfun.com for $2. Excepting another keypad, I have enough parts to build two controllers. I'm getting the 12V (or is it 13.8V ;-) from a power supply I already have on hand so I spared every expense on that. There is no speed knob on the controller, just buttons; but I can fix that without changing the PIC software. Of course it will take another PIC to read the rotary knob and simulate button pushes. My ultimate goal is to duplicate (or exceed ;0) the functionality of the expensive units.

Thanks for the support and for reading :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Keep us updated here, if you would. I'm not quite ready to purchase a DCC system for my layout, but would like to be able to test my decoder installations before I get to the club layout. (All I really need are 2 & 4 digit programming & recall, plus direction and F0 & F1 for lights.)
Sounds like your way might run about $50 or so and do what I need. I'm probably going to get in to PIC programming soon, I've got an idea for a measuring/mapping car.
Puckdropper
--
Marching to the beat of a different drum is great... unless you're in
marching band.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Puckdropper wrote:

I will post updates and I could probably take some photos if anyone is interested. I was able to get the second board about half done last night. I still need to get a project box to put it all in.

With some careful shopping, you should be able to get all the parts for that or maybe a little less. Futurlec has keypads for about $5, an LCD w/backlight for $10. The h-bridge is $14 from digikey and that makes up the expensive item list. Oh yeah the PIC chip is about $4. If you want to build one, I could flash a PIC with the firmware from the mini-DCC project for you.

PICs are amazing little devices, I wish I had discovered them allot sooner. My background is in software and hardware has always been my hobby. Not being real good with analog electronics, I've found that I can cram a PIC in and get something to actually work. ;-) PICs are kinda ugly on the inside, but they can really get the job done.
When I ordered from Sparkfun.com I also picked up some optical detectors. I plan to build a scale speedometer with those and a PIC chip of course. :-) I'd like to make an odometer car too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks. I'll keep this in mind, but I'm likely to at least get a simple programmer with the PIC.

Chances are, you're already using an optical detector of some kind every time you move your mouse. Computer mouses use an infrared emmitter and detector to detect pulses from a light weight plastic wheel. My plan is to take apart an old serial mouse, record the movements with a serial datalogger and use a computer to translate those movements in to a map of the layout.
Ever read Nuts and Volts magazine? They do a lot of PIC programming.
Puckdropper
--
Marching to the beat of a different drum is great... unless you're in
marching band.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Puckdropper wrote:

Good, I hope you don't go down the path of building your own programmer from one of the many cheesy schematics on the net. I bought the one I have now from www.melabs.com. It's USB powered and generates the voltages required for programming, very slick. Not cheap, but it works right every time.

I don't subscribe to it, but I've seen plenty of references to them on the net. I've been playing with an ARM development board lately. It's about 60 times faster than the PICs I typically use, plus it's 32 bits to boot. :-) It has a 3-axis accelerometer on it that's pretty nifty to tinker with. I want to replace the PIC chip in my mini-dcc project with a tiny ARM board. It should be able to let me do anything I can dream up. Lots of fun stuff out there to tinker with, I wish I didn't have to waste so much of my life doing work. ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

And what control do you like that the Zephyr doesn't offer? The Z does everything the Chief does, just not as much of it (2.5 amps vs. 5 or 8 amps, 10 address slots vs. 120 address slots).

available
parts
Well, if you want to go that way, have fun. Electronics is a hobby after all. ;-)
Paul A. Cutler III ************* Weather Or No Go New Haven *************
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Pac Man wrote:

Admittedly, I don't know all the specific capabilities of the Zephyr, but I do know that I don't really want to spend that much money. As for control, I'm big into hooking PCs and microcontrollers up to things so I "need" that ability as well. I just can't help myself. ;-)

Yup, and mixing hobbys is even more fun. :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Anthony Fremont wrote:

Just curious, but if you don't know the Zephyr's capabilities, how can you decide whether "that much" is too much?

No problem as far as the Zephyr is concerned:
Basic computer interface from the Zephyr's manufacturer: <http://www.digitrax.com/prd_compint_ms100.php
Much better 3rd party PIC-based, buffered commercial interface is available here: <http://www.rr-cirkits.com/
DIY version of the PIC-based interface here: <http://users.pandora.be/deloof/page5.html
Open source, multi-platform software to tie it all together available here: <http://jmri.sourceforge.net/index.html
HTH, Stevert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Stevert wrote:

$200 is too much if I can make my own for $50. Another key factor is the learning experience of doing it myself. That's where I really find the fun, sick as that may sound. ;-)

Gee, for "only" $50 and I can _receive_ loconet traffic. I'm just too much of a tightwad for that. ;-)

Not too bad, but I have my own soldering iron. ;-)

Bingo, now we're on the same page. :-) A nice pc board for less than $10 and I can supply the rest, cool. From what I have read so far, Loconet seems the best solution for two-way track monitoring and control. It's not as convenient has having everything talking on the rails, but IMO the electrical goings ons on the track with DCC are already convoluted enough. (:-)

I can't write Java code (well actually I never tried ;-), I'm more of a low level kinda guy using mostly assembler and some C. I don't do windows programming either other than some VB6. After a quick glance thru the JMRI site, it looks like I may be able to make use of their work anyway. AIUI, there are some pre-written applications that are apparently quite popular.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
a couple of DIY command station and other stuff can be found here:
http://www.tinet.org/~fmco/home_en.htm

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paco wrote:

Thanks for the link, nice information. :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 02 Jan 2008 23:23:39 +0100, Paco wrote:

Could be, I wouldn't know. The frenetic snowflakes across the top of your web page were so distracting I quit looking.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

{putting on combat helmet}
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/2/2008 6:43 AM Anthony Fremont spake thus:

A belated reply, and please forgive any ignorance of the subject on my part. But I just have some general comments and questions.
First of all, I completely understand your desire to "roll your own" DCC; it's exactly what I would do were I to venture into this world.
But it seems to me you're up against a fundamental limitation. On the controller side, it seems pretty easy to build the equipment (controllers, boosters, etc.) and even to program it, tie it to a computer, etc. But aren't you forced to choose between commercially-available *decoders*? You really can't build those, can you? Or are kits available?
It seems that this would tend to limit how much money you can save by building your own; or are decoders (decent ones) available fairly cheaply?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Nebenzahl wrote:

I could make my own decoders, but I could never make them as small as the store-bought. Plus, at about $20 - $25 each, they aren't that terribly expensive IMO, especially with the liberal warranty policys on them. It's the controllers and boosters that tend to cost so darn much money. Outside of the EZ Command from Bachman I haven't seen any that can be purchased for less than $150.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/3/2008 12:06 PM Anthony Fremont spake thus:

Then you're doing pretty much exactly what I would if I were ready to get into DCC.
Still curious about those DIY decoders, though ...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.