I need help finding the right Micro Controller

Jaegermann

I have a project that is strictly D I/O I am trying to light with LEDs approximately 50 to 60 micro LEDs that are simulating Headlights, brake lights and running lights and turn signals in a that are for model automobiles in a model railroad layout. The idea here is to be able to control the the lights as if there were activities in the cars parked or in a turn etc. I don't need any analog conversions or anyting like that. Although being able to change the brightness of the brake light LEDs would be ideal for which I could use an analog voltage change type of setup. I have done lots of searching but am becoming overwhelmed with the extensive amount of micro controller and PICS and such that are out there. I would prefer something very easy to program preferably BASIC but what I need most is the largerst amnout of digital outputs available. Any narrowing down help anyone can give me is greatly appreciated.

THanks

Mike Green

The 74HC595 is an 8 bit serial input / parallel output shift register that can drive 8 LEDs each and these are cascadable indefinitely, certainly to the 8 deep that you would need to independently handle 60+ LEDs. Parallax sells them, but you can get them from pretty much any electronics supplier. A string of these only needs 3 I/O pins to handle and a Stamp can certainly handle this. You could download a copy of the StampWorks Manual for a description (and sample code) for handling this : www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/stampworks/List/1/ProductID/144/Default.aspx?SortField=ProductName%2cProductName.
Look at Experiment #23.

Post Edited (Mike Green) : 11/18/2007 6:56:08 AM GMT

T&E Engineer

Using the 74HC595 will probably be one of the easiest approach to adding more inputs but for 50-60 LEDs you would need ~6 to 8 of them. Another approach (although might be a little more software programming but doable) would be to use something like·1 MAX7219 with a BS2. This IC can handle up to 64 LEDs and there are lots of examples on this forum to use this chip with a BS2. Just an idea for what it's worth. There are certainly main options here.

Good luck.

LilDi

You might want to look at this (TLC5940)16 channel LED driver chip as well

Kevin Wood

If you do use a BS2, you can vary the led brightness by using a variable output command, like pulsout or freqout, or even a loop of on-off-pause commands.

Andy Fox

A couple of options:

Four 74F675A or NJU3715 16-bit serial-to-parallel chips will let you drive 64 LEDs.

Another solution is go here (http://www.microresearch.us/) and look into their I2C-16IO 16-bit GPIO Expander module. Four of them will do the trick, too.

Jaegermann

Thanks a bunch on the current replys, they help aout alot in narrowing things down. I have been thinking about this project a bit more and figure that multiple chips may not be a bad answer for the different sections that have to be lit, and I can narrow the ammount down too by the types of lights ie; headlights all need to be on at the same time, tail lights as well so one DO through a relay, then the brake lights would be analog adjusted in voltage. It's looking like this well be getting even more easyily achieved that I first had anticipated. I also will have to light buildings that have some random lights that turn off and on too but this follows the same idea with nothing more than a timer as to when they go on and off, to simulate someone turning the lights on or off durring the night phase of the scene. All in all THANKS SO MUCH FOR YOUR INFO. I will persue those leads.

Peter