Questions around RTC in M4 Stellaris

Alessandro Mendes

I am looking for a example code for RTC in the M4 but is hard to find.

I found some codes line and I was testing the code below:

ROM_FPULazyStackingEnable();

SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);

SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER2); //enable the timer clock

TimerLoadSet(TIMER2_BASE,TIMER_A,ROM_SysCtlClockGet());
TimerConfigure(TIMER2_BASE, /*TIMER_CFG_RTC*/TIMER_CFG_32_RTC);
TimerRTCEnable(TIMER2_BASE);
TimerEnable(TIMER2_BASE, TIMER_A);

while(1)

{
TIMER_RTC_VALUE = TimerValueGet(TIMER2_BASE,TIMER_A);

}

The value in the TIMER_RTC_VALUE is always the same.

Anybody has any some sugestion to help me?

Thanks,

Alessandro

over 13 years ago

0 Petrei over 13 years ago

Guru 26105 points

Hi,

You must configure the CCP pin of that timer and apply an external 32.768 KHz pulse to that input. Internally this is divide d by 2^15 to get 1 sec which is then the input to RTC timer.

Petrei

0 Alessandro Mendes over 13 years ago in reply to Petrei

Prodigy 100 points

Hi,

So I need to add more a clock signal (external) to CCP pin (the same that M3)? The M4 doesn't share de 32.768Khz from external clock with the all internalperipherals?

Thank you,

Alessandro

0 Petrei over 13 years ago in reply to Alessandro Mendes

Guru 26105 points

Hi,

That usual 32.768 KHz is only for hibernation module - nothing in common with the timer in RTC mode. The CCP pin is shown in data sheet manual.

Petrei

0 Alessandro Mendes over 13 years ago in reply to Petrei

Prodigy 100 points

Petrei, thank you very much!

Alessandro

Arm-based microcontrollers

Arm-based microcontrollers forum

Questions around RTC in M4 Stellaris