Inconsistant time using interupts
Hi guys,
Im currently using Darrels DT_HID include file to control the USB aspects of my project and it works greatand I am also using his DT_INTS-18 include and have setup my PWM routine in an INT_INT interupt and it works but with 1 slight thing that I cant for the life of me figure out.
Whats happening is that my project can set the pwm down to 1 millisecond and im using both channels for the pwm (its to control 2 DC powerheads for a marine reef tank) and have hooked up 2 LEDS to the pins (RC1 & RC2) and they flash away happily but they dont keep a constant rate, you can see them slow down for any period of time from a fraction of a second to maybe a second.
I have tried changing to different interupts and either they dont swap over or when I tried TMR0 (I think it was) they ran about 10 times faster than they should and I got errernous twitching on port A 1 & 2.
Im using an 18F2455 with a 4Mhz xtal and have a dallas DS18S20+ temp probe constantly reading the temp and displaying the info on an LCD screen (Hence why I used the interupt for the pwm routines otherwise because of the LCD and its pauses it needs etc, it ran way too slow)
Here are my settings for the ports etc.
and here is the interupt setup using Darrels routines.Code:ADCON0 = 0 'Set ADCON0 ADCON1 = %00001111 'Set D i/o CMCON = 7 'Disable Comparators CCP1CON = %00001100 'set pwm CCP2CON = %00001100 'set pwm TRISA = %00000000 'set PORTA as all output TRISB = %00000000 'set PORTB as all output TRISC = %00000000 'set PORTC as all output PR2 = 63 T2CON = %00000110 ' Start Timer2, Prescaller 1:16
My wavemaker code is a bit long winded looking but it works (probably an easier way to do it, but this is the way I could figure it out etc, and it dosnt take long to execute because its using case's so it only does 1 section per powerhead at a time)Code:INCLUDE "DT_INTS-18.bas" ; Base Interrupt System INCLUDE "ReEnterPBP-18.bas" ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler USB_Handler INT_Handler INT_INT, _Do_WaveMakers, PBP, yes endm INT_CREATE ; Creates the interrupt processor endasm
Ive tried using DISABLE and ENABLE at each end, and even INTCON.6 = 0,INTCON = 1 to try to stop anything that could be possibly interferring with the routine when its executed etc, but didnt seem to make any difference.Code:Do_WaveMakers: if PHWAVEBOX = 0 then 'No wavebox mode so we ramp up and down the power select case PH1PHASE case 0 'Ramp up the powerhead PH1TIMER = PH1TIMER +1 if PH1TIMER >= 100 then '10th of a second count PH1TIMER = 0 PH1PWR = PH1PWR + (ramp_step/10) 'now add calculated step value endif if PH1PWR > PHMAX then PH1PWR = PHMAX PH1PHASE = 1 endif case 1 'At MAX power so hold there for duration if PH1TIME < PHSECS then if PH1TIME = (PHSECS/2) -2 and PHOVER = 2 then PH2PWR = PHMIN PH2PHASE = 0 PH2TIME = 0 endif PH1TIMER = PH1TIMER + 1 if PH1TIMER = 1000 then PH1TIME = PH1TIME + 1 PH1TIMER = 0 endif else PH1TIMER = ramp_step PH1TIME = 0 PH1PHASE = 2 endif case 2 'Ramp down the power to MIN value PH1TIMER = PH1TIMER - 1 if PH1TIMER <= 0 then PH1TIMER = 100 PH1PWR = PH1PWR - (ramp_step/10) endif if PH1PWR < PHMIN or PH1PWR > PHMAX then 'Need to have the > PHMAX as it can go below 0 which is higher than the MAX ;) PH1PWR = PHMIN PH1PHASE = 3 endif case 3 'At MIN power so hold again if PH1TIME < PHSECS AND PHOVER = 1 then 'Unless we are using the together mode (3) then we dont wait PH1TIMER = PH1TIMER + 1 if PH1TIMER = 1000 then PH1TIME = PH1TIME + 1 PH1TIMER = 0 endif elseif PH1TIME < PHMSECS and PHOVER = 0 then PH1TIMER = PH1TIMER + 1 if PH1TIMER = 1000 then PH1TIME = PH1TIME + 1 PH1TIMER = 0 endif elseif PH1TIME < PHSECS and PHOVER = 2 then PH1TIMER = PH1TIMER + 1 if PH1TIMER = 1000 then PH1TIME = PH1TIME + 1 PH1TIMER = 0 endif else PH1TIMER = 0 PH1TIME = 0 PH1PHASE = 0 endif end select select case PH2PHASE case 0 'Ramp up the powerhead PH2TIMER = PH2TIMER +1 if PH2TIMER >= 100 then '10th of a second count PH2TIMER = 0 PH2PWR = PH2PWR + (ramp_step/10) 'now add calculated step value endif if PH2PWR > PHMAX then PH2PWR = PHMAX PH2PHASE = 1 endif case 1 'At MAX power so hold there for duration if PH2TIME < PHSECS then PH2TIMER = PH2TIMER + 1 if PH2TIMER = 1000 then PH2TIME = PH2TIME + 1 PH2TIMER = 0 endif else PH2TIMER = ramp_step PH2TIME = 0 PH2PHASE = 2 endif case 2 'Ramp down the power to MIN value PH2TIMER = PH2TIMER - 1 if PH2TIMER <= 0 then PH2TIMER = 100 PH2PWR = PH2PWR - (ramp_step/10) endif if PH2PWR < PHMIN or PH2PWR > PHMAX then 'Need to have the > PHMAX as it can go below 0 which is higher than the MAX ;) PH2PWR = PHMIN PH2PHASE = 3 PH2TIME = 0 endif case 3 'At MIN power so hold again if PHOVER = 2 and PH1PHASE = 3 then PH1PWR = PHMIN PH1PHASE = 0 PH1TIME = 0 endif if PH2TIME < PHSECS AND PHOVER = 1 then 'Unless we are using the together mode (3) then we dont wait PH2TIMER = PH2TIMER + 1 if PH2TIMER = 1000 then PH2TIME = PH2TIME + 1 PH2TIMER = 0 endif elseif PH2TIME < PHMSECS and PHOVER = 0 then PH2TIMER = PH2TIMER + 1 if PH2TIMER = 1000 then PH2TIME = PH2TIME + 1 PH2TIMER = 0 endif elseif PH2TIME < PHMSECS and PHOVER = 2 then PH2TIMER = PH1TIMER + 1 if PH2TIMER = 1000 then PH2TIME = PH2TIME + 1 PH2TIMER = 0 endif else PH2TIMER = 0 PH2TIME = 0 PH2PHASE = 0 endif end select else 'Wavebox mode select case PH1PHASE case 0 if PH1TIME < PHMSECS then PH1TIME = PH1TIME + 1 else PH1PHASE = 1 PH1TIME = 0 PH1PWR = PHMIN endif case 1 if PH1TIME < PHMSECS then PH1TIME = PH1TIME + 1 else PH1PHASE = 0 PH1TIME = 0 PH1PWR = PHMAX endif end select select case PH2PHASE case 0 if PH2TIME < PHMSECS then PH2TIME = PH2TIME + 1 else PH2PHASE = 1 PH2TIME = 0 PH2PWR = PHMIN endif case 1 if PH2TIME < PHMSECS then PH2TIME = PH2TIME + 1 else PH2PHASE = 0 PH2TIME = 0 PH2PWR = PHMAX endif end select endif CCPR1L = PH1PWR >>2 CCP1CON.5 = PH1PWR.1 CCP1CON.4 = PH1PWR.0 CCPR2L = PH2PWR >>2 CCP2CON.5 = PH2PWR.1 CCP2CON.4 = PH2PWR.0 @ INT_RETURN
The main loop basically just calls the temp sensor to see if its alive, then if it is, reads the temp and sets a couple of pins depending on some settings, displays the temp on the screen, and then if the plugged flag is true using Darrels HID routine calls the USB but only when its plugged in.
Hope someone can shed some light onto my problem as im out of ideas on what else I can try.
It couldnt be anything to it been on a breadboard could it? as I remember reading somewhere about breadboards not been brilliant for certain things etc.
Many thanks in advance,
Mark.
)
Hmmm.. the phrase 'Look before you leap' springs to mind hehe...)
Bookmarks