TM4C123GH6PM: how to calculate PWM period?

This desire (calculating PWM period) requires a "three-step" process:

• Set the MCU's System Clock
• Set the PWM Module's Clock
• (then and only then) set the PWM Module's period

SysCtlPWMClkSet() ... SYSCTL_PWMDIV_1, 2, 4, 8, 16. 32, 64 (must choose one of these 7 values)     If this function is not called the System Clock is usually the default PWM clock.

PWMPulseWidthSet() ... param 3 is the number of PWM Clock (not System clock) ticks!

You should employ those 3 functions in the order shown (via the bullet points.)    Allez (and award "Resolved" S'il Vous Plait...)

Hi Jangrez & CB1


PWM period is the time for which the signal stays on & off as defined by  duty cycle.

Now in Tiva the period is calculated with respect to the clock as

SysCtlPWMClockSet(SYSCTL_PWMDIV_1);//This function allows the default clock tied to the PWM to be divided by 1,2,4 ...

For example

Configure the PWM for 75% duty cycle.

PWMGenPeriodSet(PWM1_BASE, PWM_GEN_2, 400);//this line sets the period of PWM,here 400 is period & measured in clock ticks.

PWMPulseWidthSet(PWM1_BASE, PWM_OUT_4, 300);///this line will set the duty cycle to 75%(300ticks) of 400 clock ticks
period.


So this way you can calculate and setup the duty cycle as required.


Thank You

Sajad Rather4 said:

SysCtlPWMClockSet(SYSCTL_PWMDIV_1);   //This function allows the default clock tied to the PWM to be divided by 1,2,4 ...

It is good that you've assisted - but as the "divide by 1" is the "default" - the function "serves no purpose" - unless another value divisor (non 1) had been (earlier) employed.

Hi Cb1_mobile

Yes divide by 1 takes the default clock,Anyway the user can use the divider of his choice available.

His "choice" seems to be to adopt, "quiet."      Oh well - we both have "tried."