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Topic: What hardware can drive one long row of 100 LEDs (Read 2 times) previous topic - next topic

CrossRoads

As much as you'd. As little as selling you the board and a set of schematics and PL, to selling you a populated board with wires (could be connectorized) going out to resistors/LEDs (you'd have to specify reds/greens and how long you'd like the wire) for you to mount on something with predrilled 3mm or 5mm holes or whatever sizze LED you'd like, capable of accepting 12 bytes of data at up to 115200 baud via USB that would then turn on the appropriate LED in each byte (1 = on, 0 = off) with about 1mS of lag:
1 bit every 1/115200 of a second received, 10 bits/byte, 12 bytes: (1/115200) sec/bit * 10 bits/byte * 12 bytes = .00104 sec.

A suitable wallwart for power, 88 LEDs * .02A max= 1.76A, so a 2A supply should do nicely.

You could order some LEDs & resistors from here,
http://www.dipmicro.com/store/index.php?act=viewCat&catId=511
do some experimenting as to what brightness you'd like, using a 5V source.
I could even give you a little sketch to run on your arduino:
Code: [Select]

LEDpin = 2;
void setup(){
pinMode (LEDpin, OUTPUT);
}
void loop(){
digitalWrite (LEDpin, HIGH);
delay (1000);
digitalWrite (LEDpin, LOW);
delay (1000);
}

adjust the pin & on/off times as you wish.

I had ease of assembly in mind when I designed the board.
Should be able to obtain all parts needed from dipmicro.com, and the shift register/drivers TPIC6B595N from Avnet.com. ATMega328P (28 pin DIP) from either place; -PU or -PN is fine. -PN is just wider temperature range.

You haven't indicated if keypress is related to LEDs lighting up or vice versa, so I assume that you will be addressing that in however the keyboard connects to the PC. I won't do the PC coding part.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

David82

#26
Apr 23, 2012, 06:37 am Last Edit: Apr 23, 2012, 06:45 am by David82 Reason: 1
I'd like to skip the arduino step and go straight to the closest thing I can output commands to from a PC. Do you have an online store? Once the prototyping and testing is finished, I'd like to order these in small batches periodically. I'd want a populated board with leads for the LEDs. An 88-key grand piano's key area is 4ft wide so the longest LED lead would need to be a little over 4ft long. It would be better to have one, long, 4ftx0.5", flat, PCB with the little micro LED's on it and all of the other components. A flexible strip would be better still.

CrossRoads

Can do.
No online store, each design I do is pretty much custom.
I accept payment via paypal.
I'll send you a PM with e-mail address.
Measured my wife's baby grand, it is indeed 4 feet from edge lower to edge of upper key.
I'll use 4.5-5 feet wire so the box can sit on the edge, or be left to drape over the edge.
Box will have panel mount connectors for power cord & USB mini-B connector.
Got an idea for the boards, think 8 of them with C# thru C on them, about the limit of the lenght I can do with the license I have, and keeps the boards within 160 x 100mm.
You mention Red & Green - please explain more.
How small do you envision for "little micro LEDs"?
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

David82

It's normally done C-B. The green LED's would be the natural keys and the red LEDs would be the black keys. It's important that I can send commands to it via C# as I have the whole software side to write. I've seen those flexible strips of LEDs which is where I was getting that idea from. I'm just looking for the most elegant, cheapest solution for this project.

CrossRoads

Huh - despite looking at the keyboard several times last night, I managed to create my drawing incorrectly.
Luckily I only had to move a couple of components to fix things.

Okay, single level, or dual level on the LEDs?  These are 3mm.
Here's a layout I'm envisioning, with examples of both.
Key to key Spacing isn't quite on, but I'm pretty close. I used 0.9 from key to key, think it's a touch more.

Hmm, internet says white keys are 7/8" with 1/16" gap.
52 keys * 7/8 + 51 gaps * 1/16 = 48 11/16" Little too big.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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