Multiple PWM Outputs Question

Hi all,

One quick question that I have is will any damage be done to my Arduino Uno if I set 6 IO pins to output 5V at 20mA with a 100% duty cycle PWM? (Can the Arduino handle all of them at the same time?)
-Will this method be possible if I need to supply a constant Voltage/Current to multiple ICs?

Thanks!

Using 100% duty cycle PWM is exactly the same as digitalWrite(pinX, HIGH);.
You haven't told us why you would need PWM to do that.
6*20mA = 120mA should be fine for any Arduino.

Well.. being new to a project at school: I need to supply a constant voltage, rather than say a 90% duty cycle, and at least 20mA current.
I just wanted to make sure the Uno can handle 6 outputs, at max (however maybe 8 if adjustments are made to the project), at the same time with 5V and 20mA each.

Thanks!

You need to read the Atmel datasheet for the Atmega 328. As well as current limits per pin there are limits per I/O port.

...R

Hi,
What do you want to do with the 5V from the outputs, what is the application?

Also check this posting and then work out your current needs, not all outputs are created equal.

http://playground.arduino.cc/Main/ArduinoPinCurrentLimitations

Tom... :slight_smile:

mclaren12c:
Well.. being new to a project at school: I need to supply a constant voltage, rather than say a 90% duty cycle, and at least 20mA current.

You need a low pass filter to convert the pulses into a somewhat constant voltage. From such an RC filter you cannot draw 20mA without considerable voltage drop, so that you have to add an amplifier (transistor or op-amp) as well, to every filter.

But are you really sure of "constant voltage"? What devices will be connected to the outputs?
LEDs and DC motors don't need constant voltage, they are perfectly happy with pulses as well.