Interrupt Driven clock Timer 1

'-----------------------------------------------
' DEMONSTARTION OF A 100THS OF A SECOND TIMER
' COUNTING UP TO 255 DAYS
'
'
' FIDDLE WITH FUDGE FACTOR TO IMPROVE ACCURACY
'
' BY TIM BOX NOV 03
'-----------------------------------------------

Include "PROTON_4.INC"

DIM _100THS ' DECLARE ALL VARS AS BYTES
DIM SECS
DIM MINS
DIM HOURS
DIM DAYS
DIM TEMP_100THS
DIM TEMP_SECS
DIM TEMP_MINS
DIM TEMP_HOURS
DIM TEMP_DAYS

DIM GIE AS INTCON.7 ' ALIAS

DIM TIMER1REG AS TMR1L.WORD ' MAKE THE TIMER VAR INTO A WORD
SYMBOL FUDGE_FACTOR = 7 ' FIDDLE WITH TO IMPROVE ACCURACY
SYMBOL TMR1_VAL =((65536)-(XTAL*2500))+FUDGE_FACTOR ' CALCULATE OSC OFFSET VALUES FOR 100HZ INTERRUPT

ON_INTERRUPT INTERRUPT_ROUTINE ' WHERE TO GO ON AN INTERRUPT


GOTO START ' JUMP THE INTERRUPT CODE

INTERRUPT_ROUTINE:

CLEAR T1CON.0 ' STOP TMR1
TIMER1REG = TIMER1REG + TMR1_VAL ' LOAD TMR1
SET T1CON.0 ' START TMR1

INC _100THS
IF _100THS = 100 THEN ' UP 100TS
CLEAR _100THS
INC SECS ' UP SECONDS
IF SECS = 60 THEN
CLEAR SECS
INC MINS ' UP MINS
IF MINS = 60 THEN
CLEAR MINS
INC HOURS
IF HOURS = 24 THEN ' UP HOURS
CLEAR HOURS
INC DAYS
ENDIF
ENDIF
ENDIF
ENDIF
CLEAR PIR1.0 ' CLEAR TMR1 INTERRUPT FLAG
CONTEXT RESTORE ' END INTERRUPT ROUTINE

START:
CLEAR ' CLEAR ALL VARS
T1CON = %00000000 ' SET UP TMR1 TO HAVE 1:1 PRESCALER AND ACT AS A TIMER
PIR1.0 = 0 ' CLEAR TMR1 INTERRUPT FLAG
INTCON = %11000000 ' GLOBAL AND PERIPHERAL INTERRUPTS ON
PIE1.0 = 1 ' ENABLE TMR1 AS PERIPHERAL INTERRUPT SOURCE
T1CON.0 = 1 ' SET TIMER1 RUNNING

CLS ' CLEAR THE LCD

WHILE 1 = 1 ' MAKE AN ENDLESS LOOP
GIE = 0 ' TURN OFF GLOBAL INTERRUPTS
WHILE GIE = 1 : GIE = 0 : WEND ' AND MAKE SURE THEY ARE OFF
TEMP_100THS = _100THS ' MAKE A COPY OF THE VARS
TEMP_SECS = SECS
TEMP_MINS = MINS
TEMP_HOURS = HOURS
TEMP_DAYS = DAYS
GIE = 1 ' TURN THE INTERRUPTS BACK ON

PRINT AT 1,1,DEC2 TEMP_DAYS,":",DEC2 TEMP_HOURS,":",DEC2 TEMP_MINS,":",DEC2 TEMP_SECS,":",DEC2 TEMP_100THS

DELAYMS 100 ' SMALL DELAU

WEND ' ROUND AND ROUND WE GO

STOP