Beyond basic info needed for Basic stamp LED board set up

Bliss St.

Can anyone advise me as to what I need to purchase to make a very simple lights on and off LED board. I just want to be able to make and LED sign that i can progam the indevidual LEDS to go on and off at differant times.

I was thinking my shopping list should look some thing like this.

LEDs (x100)
Basic Stamp 2
Resistors (x?)
Bread board??

Help, I know nothing.

Franklin

First you will need something to interface the 100 leds to ~15 pins on the stamp then depending on how many leds you want to have on at once you will need some chips to handle the power supply. More info on what you plan to build (in detail) will get you me=ore precise answers.

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- Stephen

Bliss St.

I have made a model billboard as part of an installation and I want to put lettering on in LEDS, I've estimated about 100. Then I want to have the LEDs turn on and off, letter by letter, in a sequence.

Would that be complicated for extreme novice with a kinda limited time frame?

Very greatful for your help.

Franklin

If the letters aren't changing and you just want to turn them on and off that would be do-able you would wire the letters so there is one common point for each letter and switch that with a stamp pin through an appropriate power handling device.

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- Stephen

pwillard

If you are new to electronics and short on time, this is a very ambitious project.· Somewhere in your design "magic happens" to make the dots into letters.· I assume that this is why you selected the STAMP.

Seeing that you want to generate letters, you need to think of the LED's as a MATRIX· (ROWS, COLUMNS).· Look for 5x7 LED projects for a quick example.·http://forums.parallax.com/showthread.php?p=661543 With a scanning matrix, you can greatly reduce the number interface pins needed, but regardless... you need a lot.

The only realistic way to do this is to offload the task to a chip designed to do it.· Like the MAX6592 http://datasheets.maxim-ic.com/en/ds/MAX6952.pdf·· More info: http /www.maxim-ic.com/appnotes.cfm/an_pk/1033· These documents will give you an idea what you are trying to do.

The datasheet shows that you need 140 LEDS just to make a 4 Digit 5x7 matrix display.· 5x7 = 35· * 4 = 140

Honestly, even 4 DIGITS at 5x7 using discreet LED's·is a lot of work and you only get 4 letters at a time.· Now, there are some $4.00 1" Matrix LED Displays which can save you some time.· I get part # 16786-OP from MPJA.COM.

I have also done this on a small scale with a part that seems to have dried up and faded away. The OSRAM PD2435. (http://catalog.osram-os.com/catalogue/catalogue.do;jsessionid=D79A58B42C7E0CE79F21F047311F8547?act=downloadFile&favOid=020000020000462d000100b6)

You can see by looking at what I've provided that this is a pretty big project.· Good Luck.


Post Edited (pwillard) : 7/18/2007 4:08:53 PM GMT

Bliss St.

So what should I buy?

Stamp - fine but what board?

pwillard

*Nearly* all of the stamps can do SPI with the SHIFTIN/SHIFTOUT commands. This is how simple an SPI read can be implemented.

1) set LOW the Stamp Pin connected to the SPI Chip select pin.
2) SHIFTOUT DATAPIN, CLOCKPIN, MODE, [noparse][[/noparse]DATA\bytes]
3) set HIGH the stamp Pin connected to the SPI Chip select pin

Mode = MSBfirst or LSBfirst
Bytes = how many clock cycles in packet size

From the maxim datasheet:
The MAX6952 is written to using the following sequence:
1) Take CLK low.
2) Take CS low. This enables the internal 16-bit shift register.
3) Clock 16 bits of data into DIN, D15 first to D0 last, observing the setup and hold times. Bit D15 is low,indicating a write command.
4) Take CS high (while CLK is still high after clocking in the last data bit).
5) Take CLK low.


So, with the MAXIM chip, 140 LEDS, a BASIC STAMP2 and a breadboard you could probably get this working using some small amount of code and 3 dedicated SPI pins in the STAMP. A BS1 does not have this command. To do the matrix "right" you really want (4) 5x7 matrix LED assemblies.

Pete

Post Edited (pwillard) : 7/18/2007 4:16:14 PM GMT

RDL2004

Take a look at the Parallax Robogames Medal. Maybe this could be adapted to do what you want, or at least give you some ideas.

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- Rick

Bliss St.

Thanks for all your help, I am going to take my time with this one me thinks.