randomcows
New Member
I basically need some advice on the viability of the project which I'll describe below. I'm not brilliant at electronics but I'm picking stuff up pretty quickly, and I'm also not brilliant at explaining things, so please bear with me :]...
Ok, I want to control 54 RGB LEDs (Or 162 LEDs, 54 of each Red Green & Blue, won't look as good but much cheaper than proper integrated RGB LEDs). Ideally I want to be able to address each LED individually to set the colour anywhere in the colour spectrum.
I had a look at http://www.picaxeforum.co.uk/showthread.php?t=9747 and it appears that it would be possible using pulsout on various outputs to create a PWM type effect. The problem with this is that 54 LEDs would require at least 6 expensive 28X1 PICAXEs, using my ingenious (although I'm sure someone has done it before) method of connecting all the LEDs to the same 3 outputs for RGB, then having the 4th cathode or anode leg of each LED on its own output so I could cycle through the LEDs rapidly whilst changing the RGB pulses to create the colours. I wasn't too sure on the speed of the chips, although it had quite a bit of flicker on a PIC08, I'm sure would work fine/with less flicker on a faster 28X1.
I discovered an IC today which I think may solve the problem and only require a single PICAXE for the whole project. I may have misunderstood it's use however, so this is the part where hopefully someone with a bit more knowledge can help out...
Using the 74HC164 IC (8bit serial-in parallel-out shift register) in a big 24 chip daisy chain (apparently possible), would it be possible to use just a single output on the PIC chip (a 28X1 or 40X1 because I need the 20 inputs) to send a serial *pulse* every 10ms or so to create a pwm effect. Say with 5 LEDs, using 2 74HC164 chips, sending something like RGBRGBRGBRGBRGB with a 1 or 0 value -lets call it 101001011111011- would create Magenta, Blue, Cyan, White, Cyan would it not? (Just as a note I think the daisy chaining is done through the 8th bit as it were, so 2 chips gives 7+8 =15 outputs)
My hope is that sending the *pulse* will be fast enough that the lights wont flicker and will be able to show the full spectrum, but I only require 6 unique colours for this project so if worst came to worst, just having Red, Green, Blue, Cyan, Magenta, Yellow (or White) would be fine. Flicker also doesn't matter too much, it's an A level project, I need something to evaluate at the end ;]
I hope I've made enough sense for someone to work out if the arrangement using a single PICAXE with the shift registers would actually work, thanks in advance to anyone who can :]
--Mike
Ok, I want to control 54 RGB LEDs (Or 162 LEDs, 54 of each Red Green & Blue, won't look as good but much cheaper than proper integrated RGB LEDs). Ideally I want to be able to address each LED individually to set the colour anywhere in the colour spectrum.
I had a look at http://www.picaxeforum.co.uk/showthread.php?t=9747 and it appears that it would be possible using pulsout on various outputs to create a PWM type effect. The problem with this is that 54 LEDs would require at least 6 expensive 28X1 PICAXEs, using my ingenious (although I'm sure someone has done it before) method of connecting all the LEDs to the same 3 outputs for RGB, then having the 4th cathode or anode leg of each LED on its own output so I could cycle through the LEDs rapidly whilst changing the RGB pulses to create the colours. I wasn't too sure on the speed of the chips, although it had quite a bit of flicker on a PIC08, I'm sure would work fine/with less flicker on a faster 28X1.
I discovered an IC today which I think may solve the problem and only require a single PICAXE for the whole project. I may have misunderstood it's use however, so this is the part where hopefully someone with a bit more knowledge can help out...
Using the 74HC164 IC (8bit serial-in parallel-out shift register) in a big 24 chip daisy chain (apparently possible), would it be possible to use just a single output on the PIC chip (a 28X1 or 40X1 because I need the 20 inputs) to send a serial *pulse* every 10ms or so to create a pwm effect. Say with 5 LEDs, using 2 74HC164 chips, sending something like RGBRGBRGBRGBRGB with a 1 or 0 value -lets call it 101001011111011- would create Magenta, Blue, Cyan, White, Cyan would it not? (Just as a note I think the daisy chaining is done through the 8th bit as it were, so 2 chips gives 7+8 =15 outputs)
My hope is that sending the *pulse* will be fast enough that the lights wont flicker and will be able to show the full spectrum, but I only require 6 unique colours for this project so if worst came to worst, just having Red, Green, Blue, Cyan, Magenta, Yellow (or White) would be fine. Flicker also doesn't matter too much, it's an A level project, I need something to evaluate at the end ;]
I hope I've made enough sense for someone to work out if the arrangement using a single PICAXE with the shift registers would actually work, thanks in advance to anyone who can :]
--Mike