Setting up the RTC in Tivaware 2.1 and TM4C1294NCPDT Launchpad

Hi,

The timer (Timer0 in your case) may be used as 32-bit RTC if using an external 32768Hz clock input. This clock input is internally divided up to 1 second and the 1 second count is added to the timer register. 

In your case, you may think also to use the hibernation module RTC timer.

Petrei

hey,

How do I use the external 32 k clock input? I looked at all the timers and they all have ccp pins that do not go to pins 66 or 67 (pins on the micro controller that are hooked up to the 32 k osc)

I'll look at the hibernation RTC module. 

thanks,

dan

Thanks Petrei. I got it to working with the hibernation module. To anyone that what to see a working example of the RTC:

#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include "inc/hw_hibernate.h"
#include "inc/hw_memmap.h"
#include "inc/hw_ssi.h"
#include "inc/hw_types.h"
#include "driverlib/gpio.h"
#include "driverlib/hibernate.h"
#include "driverlib/pin_map.h"
#include "driverlib/ssi.h"
#include "driverlib/sysctl.h"
#include "Nokia5110.h"

unsigned long now = 0;

int main(void) {

unsigned long ui32SysClock;

ui32SysClock = SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480), 120000000);

SysCtlPeripheralEnable(SYSCTL_PERIPH_HIBERNATE);

HibernateEnableExpClk(ui32SysClock);
HibernateClockConfig(HIBERNATE_OSC_LOWDRIVE);
HibernateRTCEnable();

Nokia5110_Init();
Nokia5110_Clear();
Nokia5110_OutString(" Time ");

while(1){
now = HibernateRTCGet(); //get the current value in seconds
Nokia5110_SetCursor(4,2);
Nokia5110_OutUDec(now);

}
}

The nokia 5110 is just used to display some text and the current value in the RTC.

Thanks,

Dan