3x64 PWM LED Control?
Chris G
Posts: 1
Hi everyone,
I've been lurking for a while but it's time for me to jump in the deep end.
I'm thinking of building a RGB LED color wall. Yes, the one thing many people would like to do on these forums...
I have a dedicated PC that I can use to send out serial commands with, so I'm not sure generating the signals is going to be too difficult. I also have utilities on my Mac that would allow me to "read" a video file, break it down into 8x8 pixels, and grab the RGB brightness for each pixel in each frame and export it to a text file. (very cool!)
The goal is to create a 8x8 grid of RGB tiles/panels. Each tile would probably need about 3-4 RGB LEDs to provide a sufficient amount of light. There would be 64 tiles in total.
My PC would be fully capable of sending out color control commands via serial, and would probably use 32 bits to do it. The first 8 bits would be the tile address (of which I would only use 6 bits), and then the next 24 bits would provide the value for each color.
How would I go about creating the hardware that took this serial output and converted it to 192 (!) PWM outputs? Are Parallax products the right way of doing this?
I've been lurking for a while but it's time for me to jump in the deep end.
I'm thinking of building a RGB LED color wall. Yes, the one thing many people would like to do on these forums...
I have a dedicated PC that I can use to send out serial commands with, so I'm not sure generating the signals is going to be too difficult. I also have utilities on my Mac that would allow me to "read" a video file, break it down into 8x8 pixels, and grab the RGB brightness for each pixel in each frame and export it to a text file. (very cool!)
The goal is to create a 8x8 grid of RGB tiles/panels. Each tile would probably need about 3-4 RGB LEDs to provide a sufficient amount of light. There would be 64 tiles in total.
My PC would be fully capable of sending out color control commands via serial, and would probably use 32 bits to do it. The first 8 bits would be the tile address (of which I would only use 6 bits), and then the next 24 bits would provide the value for each color.
How would I go about creating the hardware that took this serial output and converted it to 192 (!) PWM outputs? Are Parallax products the right way of doing this?
Comments
Frankly - 24bit color might be overkill since your matrix is only 8x8. so you might be able to trim that down to 16bit for all three colors, then use the spare info for transition speed. (i,e, 0= change to this now, and anything else is how long to take to 'fade' to the intended color.) I would also suggest a 'broadcast' color change that all of the tiles listen to - so you can change the entire wall to 'red' or 'black' with one command and transistion speed. (would be a cool effect seeing all the tiles on different colors all fade to the target together.
you might be able to build multile tile controllers (i.e. one module control 3 or more tiles) but I think the modular would be cool. The only problem would be making sure the signal is getting to everybody. (not so easy in lower forms of basic stamp - but might be a fun task for SX chipset here - and at 10$ a board for the developer boards, thats 640$ for the whole grid for independent microcontrollers - a heck of a lot better then 3200$ for 64 bs2 (!)
Then again - it might be simpler to use something like an Analog Devices ADP3166 which appears to have 4pwm built into it.
http://www.analog.com/en/prod/0,,766_820_ADP3166,00.html
(shrug)
We have seen code for the dimming lights in the forums just recently (both ac power as well as 3 strands of RGB ropes) - so maybe the answer is in there.
http://forums.parallax.com/forums/default.aspx?f=21&m=73867
he is contiplating making an 8x8x3 pwm controlled matrix as well from one SX52 chipset. (impressive!)
and already has code for 16 pwm channels on one SX.