3 channel PWM with customize duty cycle

[HenrikOlsson]

Hi,
That looks to be correct but I haven't tried it. Obviously you have to write code in the interrupt handler to take care of whatever needs to be taken care of when it sees the signal but yes, interrupts work like that.

You declare the interrupt at the beginning of the program. Then, whenever PortB.0 goes high the execution will jump to the label you specify (Faultsignal in this case). It executes the code there and when it sees the Resume keyword it returns to where it left off.

Don't try to incorporate it in your application directly, play with it a bit first. Make a LED blink continously and have the interrupt toggle another LED so you see how it works, then move on to incorporate it in your application.

With that said ON INTERRUPT isn't the most effective of handling interrupts but I won't go into that right now. There are TONS of info on interrupts on this forum, do a little searching and reading.

[photoelectric]

hi,

OK i will play it using LED first. The port B0 that i declare says that when the fault signal detect 5V is the normal operation, when suddenly changes to 0v, port B0 automatically goes to my interrupt handler to do whatever need to be done.
So, my question is:

1. did portb0 can detect directly 5v without adding extra codes that define the values of voltages?
2. if yes, can i use pull-up resistor with push-up button to create a changes signal to the portb0 and see the interrupt works or not?
3. if not, what others method to create a changes signal to the portb0?

thanks,
photoelectric

[HenrikOlsson]

Hi,
The interrupt can be triggered on either the rising or falling edge of the signal connected to PortB.0 (ie the interrupt fires when the signal changes state). You select rising/falling edge by setting or clearing OPTION_REG.6

If, during normal operation, the signal connected to PortB.0 is high and it goes low when there's a problem you want to set it up so it interrupts on the falling edge. (OPTION_REG.6 = 0)

Yes, to test it, pull up PortB.0 with a resistor and use a switch/button/whatever to pull it low and trig the interrupt. Note that you are likely to get some contact bounce with a mecanical switch/button which may trig the interrupt several time for each press of the button.

[photoelectric]

hi,
i try to test my simple interrupt on my real PIC simulation.
below is my codes:

led     VAR     PORTC.4

        TRISB.0 = 1 'set port bo to input
        ON INTERRUPT GoTo myint ' Define interrupt handler
        INTCON = %10010000      'Enable RB0 INTERRUPT
        OPTION_REG.6 = 0        'Interrupt on rising edge of RB0/INT pin

loop:   High led                ' Turn LED on
        GoTo loop               ' Do it forever


' Interrupt handler
        Disable                 ' No interrupts past this point
myint:  
Low led                 ' If we get here, turn LED off
        'Pause   500             ' Pause .5 seconds        
        INTCON.1 = 0            ' Clear interrupt flag
        Resume                  ' Return to main program
        Enable
        
        End

turns out when i enable Pause my interrupt works ok but i turns off pause it wont interrupt at all.
Please help explain what cause the problem.

[HenrikOlsson]

Hi,
I bet it works just fine. It's just that when you don't have the Pause there you don't see it becase the main routine keeps turning ON the LED all the time.

The interrupt routine turns it OFF and a couple of microseconds later the main routine turns it ON again.

[photoelectric]

Hi,

OIC. tq
So, i notice that the led will turn off whenever the faultsignal is change BUT after a few milisec it turns ON back.
The problem on my design is that i dont know how much time the fault signal will be interrupted before it back to normal operation

What should i do if i want the led to turn off until the fault signal back to normal operation which 5V again?

any example for me?

photoelectric

[HenrikOlsson]

Like I said, it turns ON again because YOU turn it on in your main loop - continously. If you don't want it to turn on again then stop turning it on. Set it one time, before you enter the loop.

If you want it to trig (turn off the LED) with an interrupt but then start "working" again as soon as the fault signal "goes away" then simply read the state of the pin in your Main routine and turn on the LED once it's high:

Main:
If PortB.0 = 1 THEN     'Turn on LED only when signal is high.
  HIGH LED
ENDIF
'Do whatever else needs to be done.
Goto Main

If want it to trig with an interrupt and stay off untill another input "restart it" then use a flag/semaphore:

FAULT VAR BIT
LED VAR PortC.4
Restart VAR PortC.5   'Pulled up thru resistor, pull to GND to "activate"
 
High LED
 
Main:
 If Fault = 1 then            'If we are in fault state...
  If Restart = 0 then        '...we check the restart button....
   HIGH LED                '....if it's pressed we turn LED on again...
   Fault = 0                '...and reset the fault flag/state
  ENDIF
 ENDIF
'Do whatever else here.
Goto Main

Then, in your interrupt routine you turn off the LED and set the Fault flag, like:

LOW LED
Fault = 1    'Set flag

Finally, be careful with the word Loop as a label, in newer versions of PBP that is a reserved word and can't be used as a label, what version are you using.