AVR064: A Temperature Monitoring System with LCD Output: Main.h File Reference

Calibrate the internal OSCCAL byte, using the external 32,768 kHz crystal as reference.

00108 {
00109     unsigned char calibrate = FALSE;
00110     int temp;
00111     unsigned char tempL;
00112 
00113     CLKPR = (1<<CLKPCE);        // set Clock Prescaler Change Enable
00114     // set prescaler = 8, Inter RC 8Mhz / 8 = 1Mhz
00115     CLKPR = (1<<CLKPS1) | (1<<CLKPS0);
00116 
00117     TIMSK2 = 0;             //disable OCIE2A and TOIE2
00118 
00119     ASSR = (1<<AS2);        //select asynchronous operation of timer2 (32,768kHz)
00120 
00121     OCR2A = 200;            // set timer2 compare value
00122 
00123     TIMSK0 = 0;             // delete any interrupt sources
00124 
00125     TCCR1B = (1<<CS10);     // start timer1 with no prescaling
00126     TCCR2A = (1<<CS20);     // start timer2 with no prescaling
00127 
00128     while(ASSR & (0x01 | 0x04));       //wait for TCN2UB and TCR2UB to be cleared
00129 
00130     Delay(1000);    // wait for external crystal to stabilise
00131 
00132     while(!calibrate)
00133     {
00134         __disable_interrupt();  // disable global interrupt
00135 
00136         TIFR1 = 0xFF;   // delete TIFR1 flags
00137         TIFR2 = 0xFF;   // delete TIFR2 flags
00138 
00139         TCNT1H = 0;     // clear timer1 counter
00140         TCNT1L = 0;
00141         TCNT2 = 0;      // clear timer2 counter
00142 
00143         while ( !(TIFR2 && (1<<OCF2A)) );   // wait for timer2 compareflag
00144 
00145         TCCR1B = 0; // stop timer1
00146 
00147         __enable_interrupt();  // enable global interrupt
00148 
00149         if ( (TIFR1 && (1<<TOV1)) )
00150         {
00151             temp = 0xFFFF;      // if timer1 overflows, set the temp to 0xFFFF
00152         }
00153         else
00154         {   // read out the timer1 counter value
00155             tempL = TCNT1L;
00156             temp = TCNT1H;
00157             temp = (temp << 8);
00158             temp += tempL;
00159         }
00160 
00161         if (temp > 6250)
00162         {
00163             OSCCAL--;   // the internRC oscillator runs to fast, decrease the OSCCAL
00164         }
00165         else if (temp < 6120)
00166         {
00167             OSCCAL++;   // the internRC oscillator runs to slow, increase the OSCCAL
00168         }
00169         else
00170             calibrate = TRUE;   // the interRC is correct
00171 
00172         TCCR1B = (1<<CS10); // start timer1
00173     }
00174 }


Defines
#define	cbi(port, bit) (port &= ~(1<<bit))
#define	CONTRAST ((unsigned char ) (0xE7))
#define	DAY ((unsigned char ) (0x4F3))
#define	FALSE 0
#define	HOUR ((unsigned char ) (0x4F0))
#define	MINUTE ((unsigned char ) (0x4F1))
#define	MONTH ((unsigned char ) (0x4F4))
#define	Nr_of_hex_bytes_to_send 11
#define	OFFSET ((unsigned char ) (0x4FA))
#define	REVISION_H 0x30
#define	REVISION_L 0x33
#define	sbi(port, bit) (port \|= (1<<bit))
#define	SECOND ((unsigned char ) (0x4F2))
#define	SET_POINT ((unsigned char ) (0x4F7))
#define	TEMP_HIGHBYTE ((unsigned char ) (0x4F8))
#define	TEMP_LOWBYTE ((unsigned char ) (0x4F9))
#define	TRUE 1
#define	YEAR_HI ((unsigned char ) (0x4F5))
#define	YEAR_LO ((unsigned char ) (0x4F6))
Functions
void	Delay (int)
	Delay-routine.
void	Initialization (void)
	Initialize the different modules of the ATmega169(P).
void	OSCCAL_calibration (void)
	Calibrate the internal OSCCAL byte, using the external 32,768 kHz crystal as reference.

Main.h File Reference

Detailed Description

Defines

Functions

Define Documentation

Function Documentation