PWM duty-free and resolution (RPM)

Duty cycle is the ratio of the on time to the period
The effect is basically the same when the impulse is equal and the narrow pulse with different shape is added to the link with inertia.
Duty cycle: is the output of the PWM, the high-level hold time and the PWM clock cycle time ratio, such as a PWM frequency is 1000Hz, then its clock period is 1ms, is 1000us, if the high-level occurrence of the time is 200US, Then the low-level time must be 800us, then the duty-free ratio is 200:1000, that is, the duty ratio of the PWM is 1:5.

Resolution: that is, the minimum duty ratio can be achieved, such as 8-bit PWM, the theoretical resolution is 1:255 (single slope), 16-bit PWM theory is 1:65,535 (single slope).

The frequency is this: such as 16-bit PWM, its resolution reached 1:65,535, to achieve this resolution, T/C must be counted from 0 to 65535 to achieve, if the count from 0 to 80 and from 0 to 80 ... Then it has a minimum resolution of 1:80, but it is also fast, which means that the PWM output frequency is high.

Double slope/single slope:

Suppose that a PWM counts from 0 to 80, and then counts from 0 to 80 .... This is a single slope .

Suppose that a PWM counts from 0 to 80, and then counts from 80 to 0 .... This is the double slope .

It can be seen that the double slope of the count time is one times more, so the output of the PWM frequency is half slower, but the resolution is 1: (80+80) =1:160, is the increase of one times.

PWM is the analog way to stabilize the output, by adjusting the PWM duty cycle (resolution), and the period to adjust the voltage and current size.

PWM duty-free and resolution (RPM)