iam new to the arduino community and do have some questions about a project I want to realize and public as a howto.
I want to control 8 RGB LEDS separately (light intensity and color). I thought doing all this in 3 development steps:
1# At the first step i want to control light density of 8 LEDs separately.(1 Byte)
2# I want to add the opportunity to control the full RGB spectrum of RGB LEDs - that means 24 seperate channels (3 Byte and maybe even more if visible). And if possible i want to use 1W RGB.
3# I want to control 8 3W RGB LEDs
Which Arduinoboard is going to be sufficient for my project (until #2)? Which hardware additional hardware like resistors... do i need (until #2)?
I know there are a lot of questions like this here, but no thread I read could answer my questions.
Which Arduinoboard is going to be sufficient for my project
Anything will do.
However you will need external hardware if you are going to control LEDs that take more than 20mA.
Power LEDs are difficult to drive correctly if you are a beginner with no experience in electronic design. It is best to get one of the pre built power LED modules like this one:- http://neuroelec.com/hp-rgb-led-shield/
Although there are lots of others available if you google.
@Grumpy_Mike thx four your reply. The shield looks like a good investment for my project, but my budget is to small for that.
Why can i only control LEDs with 20mA? I thought the Arduino is giving me 40mA for each port.
Could I drive 8 RGB LEDs with 40mA with there full power on an arduino Mega 2560 (like this one: http://bit.ly/yCGOQR - ebay link)? Would i be possible to control light density and color as well?
I thought the Arduino is giving me 40mA for each port.
No 40mA is the point at which damage starts to occur. It is not advisable to run it at this current.
You could push it to 30mA but doing so for a lot of outputs makes you run into other limits on the chip like 200mA total through the +5V line and the group restrictions on the ports. See the data sheet, section 28, for full details.
Would i be possible to control light density and color as well?
Yes if you can control colour you automatically can control light density and vice verca.
However you do talk about 1W and 3W LEDs they are a totally different matter.
24x TIP122
8x 1W RGB LEDs
1x constant current supply
hand full of resistors
1x arduino compatible board with at least 24 I/O Ports
and sufficient cooling for the TIP122
Could that work as a head start?
Is it true that i could also use ports without PWM to control the transistors? is this as good (same effect) as the hardware pwm?