Chistmas 2009 Project Help

[zsh8me2]

I am starting early on Christmas projects because I am still learning. I would like to build a circuit with LED's, that light individually (to simulate someone writing) and stay lit until all are lit for a certain amount of time (10 to 30 seconds) and maybe flash at the end. I'm not asking for a built circuit, just some direction, I don't mind doing research to figure stuff out, I just need general direction (although I may need some help at some point during the project). This project may include 100 to as many LED's as needed. I would like to use components to build this, but if a micro controller would be more economically feasible I am open to doing (and learning) that option. Any help would be greatly appreciated.

Thanks in advance,



C

 

[duffy]

You up for a microcontroller? Trying to wrangle a hundred or more led's into doing what you want is tough any other way. With a micro, you can matrix them. Led's will matrix beautifully - they work as their own matrix diodes. With a matrix, you only need 20 wires instead of a hundred and one, and 10 current limiting resistors instead of a hundred.

 

[3v0]

The 74HC595 or more modern versions with more drive are often used to drive christmas light displays.

It is so popular that it has its own forum
Olsen 595 - Do It Yourself Christmas Forums

 

[zsh8me2]

hey, I had a revelation @ dinner tonight (dinner took 3 hours, I had a little time to think), when you posted about a matrix and 20 connections I didn't understand until tonight, (please tell me if I'm wrong) to do this I would have 10 rows of 10 columns. I would connect the anode of each LED to a PNP transistor in each column and the cathode of each LED to a NPN transistor in each row. 10 + 10 = 20 connections correct? Each transistor would have to have a current rating of each LED x 10? I didn't google this, I have just been mulling this over for a day or two and this is what I come up with, hope it's correct. I understand more & better when I figure this stuff out on my own. So for my project I have to use some shift registers (+ output? for NPN) and add some inverters ( to take + output to - for PNP), add some latches to keep each LED on (until reset), and maybe a 555 monostable for my ending delay reset?

Thanks for the help

C

 

[3v0]

This is what duffy posted about. As he said this is much easier with a micro controller.

Use the microcontroller to shift bits into 3 cascaded 74HC595's which have PNP (col) and NPN (row) transistors on their outputs. You do not need latches or inverters. The 74HC595 latch the bits and you shift out inverted bits for the PNP bits.

It is a common thing. You may find a schematic if you google.

hey, I had a revelation @ dinner tonight (dinner took 3 hours, I had a little time to think), when you posted about a matrix and 20 connections I didn't understand until tonight, (please tell me if I'm wrong) to do this I would have 10 rows of 10 columns. I would connect the anode of each LED to a PNP transistor in each column and the cathode of each LED to a NPN transistor in each row. 10 + 10 = 20 connections correct? Each transistor would have to have a current rating of each LED x 10? I didn't google this, I have just been mulling this over for a day or two and this is what I come up with, hope it's correct. I understand more & better when I figure this stuff out on my own. So for my project I have to use some shift registers (+ output? for NPN) and add some inverters ( to take + output to - for PNP), add some latches to keep each LED on (until reset), and maybe a 555 monostable for my ending delay reset?

Thanks for the help

C

 

[zsh8me2]

I know some of the questions I am about to ask will have conflicting answers but here I go-

What micro-controller;

1 Is most economical
2 Is most Versital (for price per piece)
3 Has an easy to learn programming language (I've used PLC ladder logic,
never used BASIC, or C, or any other computer language)
4 Is easily upgraded


Thanks,



C

 

[3v0]

Let me start by saying you are asking the wrong questions.

To work with microcontollers you need the chip, the hardware to program/debug it, a toolchain, and most importantly help when you get it trouble. We all do.

On this forum a lot of people use PICs some use AVRs. Both are execlent. The AVR people are in the minority so the support for PICs is better. AVR help can be found on AVR freeks.

I like to start people with the PIC18 family. There is a nice range of chips in this family and may can be had in DIP packaging. The development enviroment and C compiler are free from microchip. There is also a execlent basic compiler named swordfish, it does about everything c does and is about as complex. Either is good. Both take time to learn.

For people that are learning I suggest the Junebug (PICkit2 clone + tutor) from blueroomelectronics. Bill the engineer who designed it posts here. He and others provide help. Another option is to buy a PICkit2 or PICkit3 and a target board. Again both good.

 

[zsh8me2]

What would be a good Mac friendly setup?

 

[blueroomelectronics]

Can you can run a Windows emulator on your Mac?

 

[zsh8me2]

Not sure, I have a MacBook Pro I purchased last year. I'll take a look around. If necessary I still have a desktop pc I could use, but I sure like using my laptop! Could you recommend a good (free ) one?

 

[blueroomelectronics]

Free what? Laptop?

If you mean free PIC programming hardware well not free but cheap, $50 will buy you a PICkit2 or my Junebug kit. The simple JDM style programmers are crap, avoid them.

MPLAB is free, and so is the SE editions of Swordfish BASIC or C18, C30, C32. There are many free toolchains for the PIC. Great Cow BASIC, JAL.

 

[zsh8me2]

Sorry I wasn't clear ( I have a hundred different things going on), I was asking about the emulator software, but thanks for the info ( you are probably a few questions ahead of me). I'll try and do a little more research and find a tutorial or 2 so that I'm a little more up to speed.

Thanks

C