Distinguish between TimerPrescaleSet vs TimerLoadSet

[32614_1489253935 0]

Hi everyone,

Im a newbie so I have a trouble,

How to distinguish between TimerLoadSet and TimerPrescaleSet

I have seen a example which timer configured :

 

    TimerPrescaleSet(TIMER0_BASE, TIMER_A, 500);
    TimerLoadSet(TIMER0_BASE, TIMER_A, 60000);

 

How to calculate the values of each timer ?

Thanks Dear!

[morry 0]

Hi!

 

Prescaler (in simple words) means that the clock driving your Timer is divided by 500 - your timer counts 500 times slower than the system clock speed.

Let's assume a system clock of 80Mhz: 80Mhz / 500 = 160kHz  --> 1/160kHz = 6,25µs for one counter step.

 

Your Timer is loaded with a start value of 60000 and counts down to 0.

So you have 60000 steps * 6,25µs = 0.375s - that is your timer period for one full count from 60000 downto 0.

 

Or as equation - easy to adapt for different values of Prescaler, TimerLoad and System Clock:

TimerPeriod = 60000 * 500 / 80MHz.