On a 74hc595 shift register could I just pwm the OE' pin to dim all the leds? Also is there a way to dim them individually? It only two registers, so is it possible to incorporate a past as possible virtual pwm on individual leds and update it fast enough to actually work?
Yes i'd imagine so, the register response time is well above arduino's, I think a max clock of 80-100Mhz. The OE would toggle the same otherwise the register would not function correctly.
See http://www.elcojacobs.com/shiftpwm/ for how to dim them individually.
The NXP datasheet for the 74hc595 states switching frequencies of max 52MHz / min 20MHz, just FYI.
There is only one OE pin, for all outputs. So basically, you can't PWM 8 led individually using 1 pin, only simultaneously. To PWM separately you have to shift-in 8 bit via DS.
Well yeah that's wat I asked, two questions really
first was answered, but do u think I can pwm it with shifting
but do u think I can pwm it with shifting
I thought , it was answered. Yes, sure. I have 6 74HC595 running right now (reliability check) , took code from here:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1278251011/all
each pin individually PWM-ed.
Interesting, it's written 2 years ago (don't know what's version IDE was), and it working on my 1.0 like a charm.
Ah, missed that post, thanks