Which microcontroler would be best.

[ID Miller]

Hello Forums.

I need some serious help and I don't know where to start. Let me describe what my project will be and hopefully there will be someone out here who can help walk me through microcontrollers.

The project is a round disk 19.5 inches in Diamater with a LED at every 10 Degrees. As well as a + in the middle with 4 LED's in each direction. So that is 52 total leds.
**broken link removed**

I would like to have the outside chasing in the directions of the arrows. and the plus leading to the center and reseting to the outside. I thought about using a 555 and 4017 and haveing 4 "chasers" making a full loop (9). But after much thought and consideration that will be a fairly large board. As well as the fact that the combination of the two can get out of sync and just "flutter" around. It would be nice if I could just get 2 "chasers" going around witha fading tail. example will be Led 5 =100% Led 4=75% Led 3=50% Led 2= 25% as it chases. But that sould be a complicated circuit. if not nearly impossible. I have no experience with microcontrollers. so i don't even know if this is possible.

The inside + will be chasing from the outside to the inside together so thats not a big problem 4LEDs on each pin out. they will not have a fader.

Is there a controller that will be better able to do this project with or should i stick witht hte 555+4017 combination. another thought would be to have a usb port on the board to be able to change the pattern with something as simple as writing new code and uploading it.


And if anyone is wondering this project is for my wheelchair bound friend who is wanting to spice up his chair a bit. we have led wheels in the front just wanting to put something on the ones in the back. Any and all thoughts on this project are appriciated. this is defentally out of my league with the microcontroller but not if i stick with the 4017. I just won't have the option of the fading chaser. Please let me know what you think. you can also email me directly at eqnorvrogers@hotmail.com

thank you for your time in reading this.

P.S. the powersupply will be rechargable batteries.

 

[mneary]

Almost any microcontroller made today will do the work. You plan to have each quadrant as a duplicate of the others? Why not wire the corresponding LED of each quadrant in series with the same LED in the other quadrants? This will mean your 4017 will be driving 9 circuits and they'll always be in sync. You'll run 9 wires around the ring for the LEDs.

A microcontroller can do the job, the simplest way would be having 13 outputs to drive the LED drivers, a few for programming, power and ground. You only really need 8 outputs if you want to learn multiplexing. With a micro, you would probably want a few pushbuttons so you can get fancy with multiple modes. Maybe a 20-pin device.

 

[philba]

If you want more general control, I'd take a look at using shift registers (74HC595). They are pretty easy drive from any micro and you will only need 3 pins to control a nearly unlimited number of LEDs.

Have you thought about persistence of vision? I don't know if your friend would be moving fast enough but you can do some very sophisticated effects (messages, images, kinetic art, ...).

 

[ID Miller]

If you want more general control, I'd take a look at using shift registers (74HC595). They are pretty easy drive from any micro and you will only need 3 pins to control a nearly unlimited number of LEDs.

Have you thought about persistence of vision? I don't know if your friend would be moving fast enough but you can do some very sophisticated effects (messages, images, kinetic art, ...).

No havn't thought about that but he doesn't have enough mobility to really get going fast at all so thats why i was looking to have the leds do all the work. i've been thinking more and more about it and i got a good email. that says this can be done witha 4017 555 combo. the catch of this project is i understand schmatics and how to solder and make pcbs. but my knowledge on what each componet does is limited. it's just a hobby i have. and i play around alot with the combo mentioned above it has alot of versital uses. but they have always been exposed ( not in a case) and enviroment seems to affect how the chips cycle and this will be in a project box ( plastic) and weather tight. and i'm not sure how it's going to behave. I'm really shooting for a programable microcontroller. but if it's going to be a real pain then i'd rather spend that real pain tracing outlines. ( i love puzzles and pcbs are like a wide open maze for me) he can program code so it's a good relationship. i'm thinking we only need another with the knowledge of how it works for a better understanding. this maybe a learning adventure for me as well.

Right now we are looking at 2 555's and 2 4017's on each wheel since he will be using blue leds which have higher voltage and wattage than the outter reds we were going to seperate them to keep the amount of componets to a minimum. and for one last odd ball question.... I've always been told that a resister needs to be put on the + side of a LED. For some reason i've always thought they worked better on the - side. which is the best bet for longest led life?

you guys are great and this is helping me greatly

 

[rjvh]

I've always been told that a resister needs to be put on the + side of a LED. For some reason i've always thought they worked better on the - side.

it doesn't matter as long you have one in one of the lead I think for drawing reasons or circuitry easy understanding reasons they put the power user always with one side to the minus pole

now there are already milion examples that that is not the case (electrical system in cars) so it realy doesn't matter

Robert-Jan