Interrupt and Time Out

[Bruce]

Just setup Timer1 with a variable to count Timer1 over-flows.
No need for interrupts on the timer, just monitor TMR1IF overflow
interrupt flag bit, and let Timer1 do everything for you in the
background.

This gives you roughly 5 seconds at 20MHz.

DEFINE OSC 20

' I/O definition
'
TRISB = %10000001   ' Set PORTB (0)INPUT (1-5)OUTPUTS
T1CON = %00110000   ' Timer1 1:8 prescale. Timer1 off

' Variable Definition
'
Switch              VAR PORTB.0
Red                 VAR PORTB.1
Green               VAR PORTB.2
Blue                VAR PORTB.3



PushHowManyTimes    VAR Byte
PWMVariable         VAR Byte	' PWM Variable 1-9
PWMVariableTimeOut  VAR Byte	' 5 second Timeout (100 loops of 50mS)
storedloop          VAR Byte
onled               VAR Byte

Timer VAR BYTE    ' Holds timer ticks. 1 tick = 65,536*Tosc*prescale
Timer = 0            ' Clear on start                        

' register and interrupt definition
'
CMCON = 7          ' Disable analog comparator on PORTA... not needed as now
OPTION_REG=0       ' enable pull-up resistor on PORTb
                   ' Interrupt on falling edge of RB0
INTCON = %10010000 ' Enable RB0 interrupt

PORTC.0=1   ' NOTE: Just for visual test | LED blinking every 5 S
TRISC.0 = 0

On Interrupt Goto ProcedureSwitcher

' Variable initialisation
'
'PORTB = 0             ' Reset all outputs on PORTB
PushHowManyTimes = 0

ReStart:
    TMR1H = 0
    TMR1L = 0   ' Clear time counts before Timer1 re-start
    PIR1.0 = 0   ' CLear over-flow flag before enable
    T1CON.0 = 1 ' Turn Timer1 back on before entry into MainProcedure

'Main Procedure

MainProcedure:
    Select Case PushHowManyTimes
     case 1
          Gosub resetleds
          PWMVariable = 1
          PWM BLue,1,100
     Case 2
          Gosub resetleds
          PWMVariable = 2    
          PWM blue,25,100
     Case 3
          Gosub resetleds
          PWMVariable = 3        
          PWM blue,255,100
     Case 4
          Gosub resetleds
          PWMVariable = 4        
          PWM green,1,100
     Case 5
          Gosub resetleds
          PWMVariable = 5        
          PWM green,25,100
     Case 6
          Gosub resetleds
          PWMVariable = 6        
          PWM green,255,100
     Case 7
          Gosub resetleds
          PWMVariable = 7        
          PWM red,1,100
     Case 8
          Gosub resetleds
          PWMVariable = 8        
          PWM red,25,100
     Case 9
          Gosub resetleds
          PWMVariable = 9        
          PWM red,255,100
     End Select
     
     ' IF PIR1.0 = 1 TMR1 register overflowed (must be cleared in software)
     IF PIR1.0 THEN       ' IF Timer1 has over-flowed then
        Timer = Timer + 1 ' Increment Timer variable
        PIR1.0 = 0        ' Clear over-flow/int flag
        ' @20MHz 200nS * 65,536 * 8 = 0.1048576 seconds per over-flow
        ' 0.1048576 * 48 = ~5.033 seconds before jump to NextStage
        IF Timer >= 48 THEN NextStage
     ENDIF
    Goto Mainprocedure


ResetLEDs:
    Low PortB.1                             ' reset output to PORTB
    Low PortB.2
    Low PortB.3
    Low PortB.4
    Low PortB.5
Return

NextStage: ' Dont really know what you need here. Just a visual test
'    T1CON.0 = 0 ' Turn off Timer1 if you need to here
     Timer = 0   ' Clear Timer var on entry here
'    TMR1H = 0
'    TMR1L = 0   ' CLear timer count registers as required
     PORTC.0 = PORTC.0 ^ 1   ' Toggle LED for test
    ' Do something here, etc,,
     GOTO ReStart ' When you're ready to start all over
    
' Interrupt handler stuff here
'
Disable                                     ' Disable interrupts in handler
ProcedureSwitcher:
    PushHowManytimes = PushHowManytimes + 1     ' Changing task
    If PushHowManytimes = 10 Then PushHowManytimes=1

Here:
    While SWITCH = 0                        ' waiting until
    wend                                    ' push-button is release
    pause 100                               ' debounce time
    If switch = 0 then here
    PIR1.0 = 0 '  Clear Timer1 over-flow flag
    Timer = 0  ' Clear Timer counts before return
    INTCON.1=0                              ' reset RB0 interrupt flag
Resume                                      ' Return to main program

Enable                                      ' Enable interrupts after
                                            ' handler
                                            
    END