DT Instant Interrupts

[krohtech]

Hello All,

Darrel,

I love the Instant Interrupts. Is it possible to use it with multi SPWM? I need a system LED that just blinks at a constant speed like 4 times a second. to show that the pic is working.

[Darrel Taylor]

Is it possible to use it with multi SPWM?

I rewrote the old SPWM module to work with DT_INTS some time ago.

DT_INTS-14 (SPWM_INT - Multiple Software PWM)
http://darreltaylor.com/DT_INTS-14/SPWM.html

But if you just want to blink an LED at a certain rate, the Timer Template might be more appropriate.

DT_INTS-14 (Timer Template)
http://darreltaylor.com/DT_INTS-14/TimerTemplate.html
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[krohtech]

Oh, sorry I forgou to mention I am using an 18F PIC. Can I use the timer template -14?

[skimask]

Oh, sorry I forgou to mention I am using an 18F PIC. Can I use the timer template -14?

You're talking about one of my favorite 'staples' whenever I build something...I call it a 'heartbeat'...
I have an LED connected to a specific pin...
I set up Timer 0 to run at a decent rate according to my main clock speed...i.e. once per second-ish, 4 times per second-ish, doesn't really matter, as long as I can see it blink.
Then every Timer 0 overflow, I increment a byte variable, last I set the LED to follow a certain bit of that variable.
So, say I use 'temp' as my variable.
myint:
temp = temp + 1
led = temp.0 'led will flash on/off every other time thru loop
resume

If the LED flashes too fast, I use temp.1, still too fast, maybe temp.2.
Or, conversely, if I use temp.4, and that flash is too slow, I'll use temp.3, or temp.2, whatever...until I find a flash rate that works for me.

DT's Fast interrupts and SSPWM code are great pieces of code...but I think they're big time overkill for what you want...

An example cut from one of my last programs:

'CONFIG statements semi-permanently set in PBP 18F4620 .INC file
resetplaceholder:	'18f4620 code
DEFINE OSC 10
DEFINE NO_CLRWDT 1	'no extra clear watchdog timer instructions
DISABLE
CLEAR
led1 var porta.5
heartbeat var byte
startupholder:
goto skipsubs	'skip over all the commonly used subroutines
ON INTERRUPT GOTO INTHANDLER
DISABLE
INTHANDLER:	if intcon.2 = 1 then			'timer 0 overflow interrupt handler
			intcon.2 = 0
                       heartbeat = heartbeat + 1
                        led1 = heartbeat.0		'led flash about every ~1.6 seconds
' change heartbeat.0 to heartbeat.X where x = 0 - 7 to change heart beat flash rate
INTFINISH:
RESUME
DISABLE
'end of commonly used subroutines, skipsubs block for setting up registers, lcd, whatever else...
skipsubs:
	t0con = $84
        intcon = $e0
        cmcon = 7
        pie2 = $80
        trisa = 0
        porta = 0
        led1 = 0
        output led1
' change prescale value in $84 to change flash rate
ENABLE
mainloop:
' do something useless or useful here
goto mainloop
END

IF you're not using a '4620, then you'll have to figure out which registers need which values as far as interrupt and timer registers go.
I chose porta.5 because it was available. Change that to what you need also.

[Darrel Taylor]

I need a system LED that just blinks at a constant speed like 4 times a second. to show that the pic is working.

&nbsp; ... and ...

Oh, sorry I forgou to mention I am using an 18F PIC. ...

I'm thinking just the Blinky example is all you need.

DT_INTS-18 (Blinky Light)
http://darreltaylor.com/DT_INTS-18/blinky.html

Or, even better ...

DT_INTS-18 (Assembly Language Interrupts)
http://darreltaylor.com/DT_INTS-18/asm_ints.html

Same Blinky LED, without the Basic Language Interrupt overhead.

And no running Colon's
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[krohtech]

DT_INTS-18 (Assembly Language Interrupts)
http://darreltaylor.com/DT_INTS-18/asm_ints.html

Yes, this is the code I am using but I can't get it working in the same program as the multi SPWM. I am useing multi SPWM for my 8 pwm dimmers.

Also I have played with the prescaler to slow down the blink rate but have had no sucess. is there a formula for this like in the -14 version?

I will also make an attempt to digest Skymask's timer 0 overflow interrupt handler in the morning.

Thanks Darrel and Skymask. You are both very helpful.

[Darrel Taylor]

The original SPWM will not work with Instant Interrupts.
They both want complete control of the interrupts. (can't happen)

However, SPWM_INT will work with Instant Interrupts.
And yes, the version shown in the -14 section will work on the 18F's too.

DT_INTS-14 (SPWM_INT - Multiple Software PWM)
http://darreltaylor.com/DT_INTS-14/SPWM.html

SPWM_INT uses Timer1, so if you also want a Blinky light, you'll need to use a different Timer. (0, 2 or 3)

And if you want to use either of the SPWM versions, then you can't use skimask's code.
They are not compatible with ON INTERRUPT.
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