Hi,
I am thinking of building a led globe with rgb leds and for this project i need 44(leds)*3(rgb pins)=132 analog pins. I 've read a few things about the 74HC595 but it provides only digital outputs. Is there a microcontroller that provides only analog pins and if not is there no way for me to do this ? And how will I connect all of these together to an atmega328? (I am obviously not an expert so I might need a bit more info and explanation)
Thank you in advance,
Alex
If you want to control RGB LEDs with analogwrite for brightness you are using digital pins.
While confusing to many arduino beginners, the arduino analogWrite() functions by manipulating a digital output pin via PWM (pulse width modulation).
The function should have been named pwmWrite() but that seemed to have been too confusing for the original target users of the arduino project, artist and other non-geeks.
Yes I am aware of the function being an arduino user my self and having completed a couple of projects. But is it possible to use this function with non-pwm digital pins? For exanmple in arduino mega pins 13-2 are pwm and can support analogWrite(). Do pins 22-53 also support analogWrite()?
You can do PWM in software on any Arduino pin or with the 74HC595. It's just a case of switching them on/off with proper timing.
I wouldn't do it though, just buy a WS2811 LED strip and cut it into individual LEDs as required.
(I have no idea what "LED globe" looks like in your head but RGB LEDs are far easier to do with LED strips if it can possibly be done that way).
Why wouldn't you do it? Is it possible that the chip will be damaged or do you not like it for other reasons?
alex_poupakis:
Why wouldn't you do it? Is it possible that the chip will be damaged or do you not like it for other reasons?
It's more difficult and needs a lot more wires to build it.
LED strips make everything much easier.
Check this out for a variation on LED strips:
https://www.sparkfun.com/products/11821
The WS2811 and its variations is the way to go.
Good idea from Grumpy_Mike:
What you originally asked for can be done in software here:-
http://www.elcojacobs.com/shiftpwm/
Shiftpwm uses Timers 1&2 which might be a problem in some applications.
Thanx a lot guys !
This is great help!!