Need your input on multi-cog LED demo

Oldbitcollector (Jeff)

Ok gang.. I need some input..

Everyone know I'm keen on writing tutorials and helps for new users..
Ever have one of those mental blocks when writing something?

One of the items I'm working on is a short demo of multi-cog ability of the Propeller.
In this demo, I've got some LEDs at my disposal and I'm aware of the little mutli-led demo that was part of the PEkit.

Here is where you come in...

There has got to be a method to demonstrate this ability with LEDs other than simply flashing them in different times. (Boring!) Something "simple" and with "appeal".

I've been working on a multi-candle sim, but I'll bet there is more...

OBC

MagIO2

Maybe these days RGB LEDs are more interesting. You could have one COG per color and let them fade the colors.

JasonDorie

PWM them at different frequencies to make them glow (fade in, fade out) with different cycle lengths. It would demonstrate PWM, controlling LED brightness with PWM, and the fact that multiple cogs run independently. (still basically a flashing LED demo, but with a little more meat)

Oldbitcollector (Jeff)

RGB leds aren't a option this time.. Jason.. I was heading in this general direction with a candle demo, but hadn't given much thought to using PWM. A solid suggestion. Thanks

OBC

Perry

Way back in the 1930's there was a lot of interest in mechanical TV's, There were even kit's and instructions to build them at home.
http://www.nbtv.org/ The had 28 or 30 verticle lines and I think ther were som sets that were two-way like a video phone.

http://www.earlytelevision.org/mechanical.html

You could use a rotating wheel with 30 or 32 holes to make one of these. I wonder if a color sensor would be fast enough to make such a TV with a tri-color output led to display the video.

At least you could use a photo diode to make a B/W version/

Oldbitcollector (Jeff)

Hmm.. A Baird Televisor made with a rotating disc and a line of LEDs.. Sounds like an interesting project..

OBC

JasonDorie

Not trying to steal your thunder at all, but I was showing my girl my latest cutting board clock update. She gave me one of those weird looks and said, "How do you know how to do all this stuff?" I basically told her that it's a lot of very simple concepts arranged into something that's less simple, and it all runs really fast. Then I banged out the PWM demo to prove it. It's attached.

It runs on a DemoBoard, launches a PWM function on all 8 cogs with different period values. Each cog runs the PWM loop while cycling the duty value up & down, resulting in the LEDs all pulsing at slightly different frequencies. It kind of looks like really small Christmas tree lights.

doggiedoc

Here is a little PASM hack I put together from the PASM demo. Modified it to use all 8 cogs and to cycle up and down on the rate. Still boring but better.


Paul

Perry

Oldbitcollector (Jeff) wrote: »

Hmm.. A Baird Televisor made with a rotating disc and a line of LEDs.. Sounds like an interesting project..

OBC

You could build the scanning disk with retroreflective tape instead of holes. Place the disc at the back of a box using a fan motor take from an old computer. At the front of the box use one of those credit card size magnifiers ( fresnel lens). A red LED next to the fresnel lens would provide similar displays to the original neon, but it is easy to obtain white LEDs these days . A photo diode next to the fresnel lenst would allow you to capture images.

It should be relatively easy to make a 32 line display, put possibly 48 of 64 lines could be achievable. Leave out one of the reflectors to provide a blank space for synchronization.

Transmit with a stereo (one channel is audio, other is video). One of the cheap car radio FM broadcasters could provide the transmission capability's.

Gee! I should be making this.

Perry