TM4C1230H6PM: Timer, Prescale

Hello,

Well for starters, you are not using the timer in Half-Width mode. See the comments for TimerPrescaleSet in the driverlib timer.c file:

//! This function configures the value of the input clock prescaler.  The
//! prescaler is only operational when in half-width mode and is used to extend
//! the range of the half-width timer modes.  The prescaler provides the least
//! significant bits when counting down in periodic and one-shot modes; in all
//! other modes, the prescaler provides the most significant bits.

You need to use the following configuration to set the timer to work in half-width mode which will let you use TimerPrescaleSet then:

TimerConfigure(TIMER0_BASE, TIMER_CFG_SPLIT_PAIR | TIMER_CFG_A_PERIODIC);

There is a catch you need to be wary of though, which is that you would overrun the Half-timer register with your input of 80000000.

So you would need to find a way to scale that down to a value less than 65535 to fit within the 16 bit wide half-timer register.

Hopefully this information is sufficient to allow you to figure out a way to achieve your application, let me know if you have further questions

Hello Ralph,

Believe that you are (exactly) correct - however in this case - is it wise to accept the poster's desire?

user5858362 said:

I want to use TimerA of TIMER0_BASE with Prescale

As you well noted - his 'method' will:

• 'quickly & repeatedly' overflow his 'Half Timer' - requiring a 'cascade of (overflow) counts' to reach his goal
• adds the complication of a 'Prescaler'
• thus will prove 'outside of an efficient & eased solution'

Instead - the choice of a 'Full-Width' (32 bit Timer) easily accommodates those 80,000,000 counts - while 'dismissing' any need for a 'Prescaler!'

Experience teaches that when posters present (unexplained, possibly unjustified) 'needs/wants' - rarely are they the (best considered) 'Paths to Success!'

Without doubt - poster's use of a Full-Width Timer - best enables a 'Speeded, Eased & Enhanced' Solution!