I was reading in "Mastering STM32" and in the intro of PWM pulses (pg355 hard copy) said that "The square waves generated until now have all one common characteristic: they have a Ton period equal to the Toff one. For this reason they are also said to have a 50% duty cycle."
But according to RM0090 at pg. 521 and Figures 89-91 the UEV happens once the counter is equal to Period (ARR) value.
So, theoretically speaking, if I set the ARR value to 4, handle the interrupt from the UEV and toggle a pin by code, does it mean that I have just created 25% duty cycle signal? Let's say that I don't care in creating a signal at 90% (stick with this single example, 25%) duty cycle and I don't care about the extra CPU load I create.
If yes, then why do we say that only PWM signal can vary in duty cycle?
If no, could you explain what I missed from the photos I referenced from RM0090?
Thank you in advance,
