Comments on: DCC Booster Complete

By: stevenh

stevenh — Thu, 12 May 2011 23:33:21 +0000

fly3rman,
If you mean creating a circuit without using the microcontrollers then you can look at this forum post of mine from a (scayr!) few years ago:
http://www.electro-tech-online.com/general-electronics-chat/42989-l298-short-circuit-protection.html

That was me asking for assistance back then and MrAl on the forums was completely awesome with the help and support.

Hope it helps you too.

By: fly3rman

fly3rman — Thu, 12 May 2011 23:28:58 +0000

That was exactly my idea, i also identified the 0.5 ohm resistors. Can also measure the voltage there -> ohms law. But thanks for the informations =)
I actually want create a circuit without using the IC, it must be easy actually, but i suck at electronics =)
Will do some research. You should play around with rocrail btw. Using ddx->comport->booster. There is also an Ipone and Android client =)
I think i will contact you soon, some brainstorming or something. Also got some questions about your stuff.

By: stevenh

stevenh — Wed, 11 May 2011 23:39:44 +0000

fly3rman,
Your Arduino Motor Shield will provide the same current sensing that I have used for short-circuit protection. You get to do it via the microcontroller though whereas I had to do it via 555 timers.

If you look at the manual for the L298(P) you’ll see that Pins 1 and 15 are the sense pins for current overload. Usually these are just pinned to ground with low-resitance but high wattage resistors.
The datasheet is here: http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXxwur.pdf

I can’t currently find a schematic for your motor controller shield, but you’d just need to find a way to feed the sense pins into two analog-in pins on the arduino. You could then monitor the current draw and even draw graphs to see what’s going on up on the track. Of course, if the current spikes for too long (and we’re talking milliseconds) then you can cut the enable pins and save your equipment from imminent death.

I hope this helps… if you can take a high resolution macro shot of the board then I should be able to help you get this going.

Otherwise I love your short and long term goals and am happy to help where I can.

By: fly3rman

fly3rman — Wed, 11 May 2011 19:43:52 +0000

Hi, iam doing some fancy dcc stuff at the moment too.
First i started with creating dcc signal on the arduino: http://www.flyerman.org/software/dcc-auf-dem-arduino/ using http://www.oscale.net/simpledcc.
At the moment i am using rocrail (wonderfull open source stuff) to create a dcc signal with the comport of a pc.
I am boosting the signal with this h-bridge-arduino-board: http://www.dfrobot.com/index.php?route=product/product&keyword=L298P+Motor+Driver+&category_id=0&description=1&model=1&product_id=69
Ive had it here and it works flawless.

The signal from pc to “booster” is seperated with optocopplers. But at the moment ive got no short-circuit-protion. Need to find a simple and neat solution to that.

Goal is: arduino reading photosensors (your idea), arduino serial->python application and http://www.griebel-net.de/peer/rcsh/rcsh.html -> srcp -> rocrail for sensors, control and actually everything-communication.

Longtimeplan: to get that pimpy thing, because it got lan onboard, touchdisplay and use it as a srcp client somehow.
http://cgi.ebay.de/ARM-NXP-LPC1768-Development-Board-3-2-TFT-LCD-Module-/190391184647?pt=BI_Electrical_Equipment_Tools&hash=item2c5432ed07