Question

Assume a tomer clock frequency of 8 MHz. If SC = 9 and CnSC = 37 abd the PWM should have 296 Hz what value of CnV will ensure a duty cycle of 44.9%?

Answer 1

To determine the CnV value that ensures a 44.9% duty cycle for a PWM signal at 296 Hz with an 8 MHz clock and SC = 9, calculate the timer tick, total number of ticks, and set CnV to 44.9% of the total ticks.

Step-by-step explanation:

To calculate the value of CnV that will ensure a duty cycle of 44.9% for the Pulse Width Modulation (PWM) with a frequency of 296 Hz, given a timer clock frequency of 8 MHz, SC is set to 9 (prescaler), and CnSC (count until the timer compare flag is set) is 37, the following considerations must be taken into account:

• Firstly, determine the time period (T) of the PWM signal: T = 1 / Frequency = 1 / 296 Hz = 3.38 ms
• Calculate the timer tick using the prescaler applied to the clock frequency: Timer tick = 8 MHz / (SC+1), where SC is the prescaler value.
• Then, calculate the total number of timer ticks per PWM cycle: Total ticks = Timer tick × T
• Knowing that CnSC determines the PWM frequency, the value of CnV would be a percentage of the total number of ticks, specifically 44.9% of it, to achieve the desired duty cycle.

Once these values are computed, plug them into the formula to determine the exact CnV needed for a duty cycle of 44.9%.