PWM arduino uno problem?

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1

Hey guys i have been studying pwm in arduino uno. The o/p in arduino uno is from y= 0 to 255 which can be used as pwm like this
analogWrite(x,y);

What i want to know is, is there any unit for this number 0-255? It must be related to duty cycle. Can anybody tell me how to calculate duty cycle?

2

zacmackra:
Hey guys i have been studying pwm in arduino uno. The o/p in arduino uno is from y= 0 to 255 which can be used as pwm like this analogWrite(x,y);

What i want to know is, is there any unit for this number 0-255? It must be related to duty cycle. Can anybody tell me how to calculate duty cycle?

No unit.

0 is completely off. 255 is completely on. 128 is about 50%. on, 50% off.

3

zacmackra:
Can anybody tell me how to calculate duty cycle?

The Wikipedia article is reasonably clear, and not too complex. Duty cycle - Wikipedia

4

which can be used as pwm like this

No not can be used, this IS PWM
Duty cycle is a ratio and therefor has no units.
It is simply the value given in the analog write command divided by 255.