Getting Started

Chapter 8: C Pointers and Arrays

nitialize Timer/counter2 as asynchronous using the 32.768kHz watch

crystal.

< 10; i++)

cbi

ASS

TCN

TCC 1<<CS20);

gs

sei // enable global interrupt

//
gSE
gMI
gHO
}

ne second interrupt from 32kHz watch crystal

GNAL(SIG_OVERFLOW2)

gSECOND = 0;

gMINUTE = 0;
HOUR++; // increment hour
if (gHOUR > 12)

// i
//
void RTC_init(void)
{
// wait for external crystal to stabilise
for(int i = 0; i
_delay_loop_2(30000);

cli(); // disable global interrupt

(TIMSK2, TOIE2); // disable OCIE2A and TOIE2

R = (1<<AS2); // select asynchronous operation of Timer2

T2 = 0; // clear TCNT2A

R2A |= (1<<CS22) | (

// select precaler: 32.768 kHz / 128 = 1 sec between each overflow

// wait for TCN2UB and TCR2UB to be cleared
while((ASSR & 0x01) | (ASSR & 0x04));

TIFR2 = 0xFF; // clear interrupt-fla
sbi(TIMSK2, TOIE2); // enable Timer2 overflow interrupt

();

initial time and date setting

COND = 0;

NUTE = 0;

UR = 0;

// o
SI
{
gSECOND++; // increment second

if (gSECOND == 60)
{

gMINUTE++; // increment minute

if (gMINUTE > 59)

{

g