If you enable interrupts, then you need an interrupt handler. If you prefer just to monitor the
timer1 overflow flag, then disable global interrupts.
Here's one example of monitoring the timer1 overflow flag without interrupts.
Just replace the LCD port assignments & port settings to match your board. I tested this on
a LAB-X1 board.
Note: You can remove the TOGGLE 0 stuff. I used the output for a scope probe.
Code:
DEFINE OSC 4
DEFINE LOADER_USED 1
'=================================================
'Setting LCD parameters
'=================================================
' Define LAB-X1 LCD registers and bits
Define LCD_DREG PORTD
Define LCD_DBIT 4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG PORTE
Define LCD_EBIT 1
Define LCD_COMMANDUS 2000
Define LCD_DATAUS 50
ticker VAR WORD
T1LO CON $F1 ' constant values for 10mS timer1 overflows
T1HI CON $D8 ' use with 1:1 prescale at 4MHz
ticker = 0 ' clear ticker on power-up
ADCON1 = 7 ' Set PORTA and PORTE to digital
Low PORTE.2 ' LCD R/W line low (W)
Pause 1000 ' Wait for LCD to start up
'=================================================
'Initialisation of PORT's
'=================================================
PORTB = 0
TRISB=%11110000
OPTION_REG.7=0 'Enable Pull-Up's on PORTB
T1CON = 0 '1:1 prescale, internal clock
PIE1.0 = 1 'enables the tmr1 overflow interrupt
PIR1.0 = 0 'resets tmr1 interrupt flag
INTCON.6 = 0 'disable peripheral interrupts
INTCON.7 = 0 'disable global interrupts
'=================================================
'Main Program
'=================================================
pause 500 'initialise LCD
LCDOUT $FE, 1, "Hello"
LCDOUT $FE, $C0, "World"
pause 2000 'displays the above for 5 seconds
LCDOUT $fe,1
LCDOUT "-- press button"
TMR1H = T1HI ' load timer1 for 10mS interrupts
TMR1L = T1LO
waitforstart:
if PORTB.5 = 0 then
LCDOUT $FE, 1, "Timer started"
T1CON.0 = 1 'starts timer
goto loop
endif
goto waitforstart
loop: ' loop waiting for timer1 overflow
WHILE PIR1.0=0 ' timer1 overflow?
WEND ' no, keep waiting
PIR1.0 = 0 ' clear overflow flag
TOGGLE 0 ' 10mS pulse on RB0
ticker = ticker + 1 ' inc ticker
LCDout $FE,$C0,DEC5 ticker ' display ticker
' timer1 is still ticking, so we'll stop it, then add
' in our value for 10mS interrupts
T1CON.0 = 0 ' stop timer1
TMR1L = TMR1L + T1LO ' add in low byte
IF TMR1L < T1LO THEN ' did low byte overflow?
TMR1H = TMR1H + 1 ' yes, increment high byte
ENDIF
TMR1H = TMR1H + T1HI ' no, just add in high byte
T1CON.0=1 ' start timer1
GOTO Loop
END
If you want to use interrupts, here's another version using ON INTERRUPT,
Code:
DEFINE OSC 4
DEFINE LOADER_USED 1
'=================================================
'Setting LCD parameters
'=================================================
' Define LAB-X1 LCD registers and bits
Define LCD_DREG PORTD
Define LCD_DBIT 4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG PORTE
Define LCD_EBIT 1
Define LCD_COMMANDUS 2000
Define LCD_DATAUS 50
ticker VAR WORD
T1LO CON $F1 ' constant values for 10mS interrupts with
T1HI CON $D8 ' timer1 1:1 prescale and 4MHz osc
ticker = 0 ' clear ticker on power-up
ADCON1 = 7 ' Set PORTA and PORTE to digital
Low PORTE.2 ' LCD R/W line low (W)
Pause 1000 ' Wait for LCD to start up
'=================================================
'Initialisation of PORT's
'=================================================
PORTB = 0
TRISB=%11110000
OPTION_REG.7=0 'Enable Pull-Up's on PORTB
T1CON = 0 '1:1 prescale, internal clock
PIE1.0 = 1 'enables the tmr1 overflow interrupt
PIR1.0 = 0 'resets tmr1 interrupt flag
INTCON.6 = 1 'enables all unmasked peripheral interrupts
INTCON.7 = 1 'enables global interrupts
'=================================================
'Main Program
'=================================================
pause 500 'initialise LCD
LCDOUT $FE, 1, "Hello"
LCDOUT $FE, $C0, "World"
pause 2000 'displays the above for 5 seconds
LCDOUT $fe,1
LCDOUT "-- press button"
TMR1H = T1HI ' load timer1 for 10mS interrupts
TMR1L = T1LO
waitforstart:
if PORTB.5 = 0 then
LCDOUT $FE, 1, "Timer started"
T1CON.0 = 1 'starts timer
goto loop
endif
goto waitforstart
ON INTERRUPT goto BasicInt
loop: ' loop waiting for interrupt & display updates
@ NOP
GOTO Loop
' update & display ticker on each interrupt
DISABLE
BasicInt:
TOGGLE 0 ' toggle RB0 every 10mS
ticker = ticker + 1 ' increment ticker
LCDout $FE,$C0,DEC5 ticker ' display ticker
' timer1 is still ticking, so we'll stop it, then add
' in our value for 10mS interrupts
T1CON.0 = 0 ' stop timer1
PIR1.0 = 0 ' clear overflow flag
TMR1L = TMR1L + T1LO ' add in low byte
IF TMR1L < T1LO THEN ' did low byte overflow?
TMR1H = TMR1H + 1 ' yes, increment high byte
ENDIF
TMR1H = TMR1H + T1HI ' no, just add in high byte
T1CON.0=1 ' start timer1
RESUME
ENABLE
END
Once you understand how these work, you can go for the big guns, and use Darrel Taylors'
instant interrupts here http://www.picbasic.co.uk/forum/showthread.php?t=3251
Then you'll really start having fun...;o}
Timers !
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