Problem with external interrupts (B0-B2) on 18f452

[cncmachineguy]

Hi Tom, I hope you don't mind I am posting your code from the first post so its easier for folks to see. Plus it just makes it easier for me to look at your results and follow the code.

DEFINE LOADER_USED 1
DEFINE USE_LFSR 1
Include "modedefs.bas"     'this is required for RS232 comms
ADCON1=7
' Assign variable names
DBGDSPL     VAR PORTB.5      'Debug display port
CurrPuls    var byte
PulseA      var word
PulseB      var word
PulseR      var word
LastACnt    Var word
LastBCnt    Var word
LastRCnt    var word
CurrSec     var word
LastSec     var word
IntCount    var word                    
pause 10
trisb=%00000111
T0CON = %10000011       'Define Timer0 - 1:16
RCON.7 = 0
INTCON = %10110000      'Enable TMR0 & Pin B0-B2 interrupts 
INTCON2= %10000000      'Falling Edge
INTCON3= %11011000
goto start
'---------------------------------------------------------Interrupt Code
Disable                 ' No interrupts past this point
myint:
if INTCON.1<>0 or INTCON3.0<>0 or INTCON3.1<>0 then    'Pulse Interrupt
    IntCount=IntCount+1
    if INTCON3.0=1 and INTCON.1=0 and INTCON3.1=0 then PulseA =PulseA +1
    if INTCON3.0=0 and INTCON.1=1 and INTCON3.1=0 then PulseR =PulseR +1
    if INTCON3.0=0 and INTCON.1=0 and INTCON3.1=1 then PulseB =PulseB +1
 
    SerOut DbgDspl, N9600, [$1b,$2a,$80]        'turn on background lighting of debug display
    SerOut DbgDspl, N9600, [$1b,$30]
    SerOut DbgDspl, N9600, ["I:",#IntCount, " A:", #INTCON3.0, " R:", #INTCON.1, " B:", #INTCON3.1]
    SerOut DbgDspl, N9600, [$1b,$32]
    SerOut DbgDspl, N9600, ["A:", #PulseA, "R:", #PulseR, "B:", #PulseB, "S:", #CurrSec]
    INTCON.1=0 : INTCON3.0=0 : INTCON3.1=0
endif
if INTCON.2=1 then              'timer overflow interrupt
    CurrSec = CurrSec +1
    TMR0H=11 : TMR0L=186        'set tmr0 cycle count to 3002 so overflows in 1.0 sec
    'TMR0H=231 : TMR0L=147      'set tmr0 cycle count to 59283 so overflows in .1 sec
    'TMR0H=253 : TMR0L=143      'set tmr0 cycle count to 64911 so overflows in .01 sec
    INTCON.2 = 0
endif
Resume                  ' Return to where interrupt occured
Enable                   
'---------------------------------------------------------End of Interrupt code
Start:
PulseA=0 : PulseB=0 : PulseR=0 : CurrSec=0 : LastSec=0 : IntCount=0
LastACnt=0 : LastRCnt=0 : LastBCnt=0
SerOut DbgDspl, N9600, [$1b,$2a,$80]        'turn on background lighting of debug display
SerOut DbgDspl, N9600, [$1b,$30]
SerOut DbgDspl, N9600, ["Start "]
SerOut DbgDspl, N9600, [$1b,$32]
pause 10
 
On Interrupt Goto myint ' Define interrupt handler
Mainloop:
    if PulseR<>LastRCnt or PulseA<>LastACnt or PulseB<>LastBCnt or CurrSec<>LastSec then
'    SerOut DbgDspl, N9600, [$1b,$2a,$80]        'turn on background lighting of debug display
'    SerOut DbgDspl, N9600, [$1b,$30]
'    SerOut DbgDspl, N9600, ["I:",#IntCount, " A:", #INTCON3.0, " R:", #INTCON.1, " B:", #INTCON3.1]
'    SerOut DbgDspl, N9600, [$1b,$32]
'    SerOut DbgDspl, N9600, ["A:", #PulseA, "R:", #PulseR, "B:", #PulseB, "S:", #CurrSec]
    endif
    pauseus 1
GOTO Mainloop
end

My time estimate is based soley on the serout stuff. I was just taking a guess at the number of bytes sent at 9600 baud.


As for DT_INT, search it on this forum and you will find tons of help. I am not so good at finding and posting the links or I would. Basically it is an awesome include to handle all your interrupt needs. It gives you true interrupts as if you had ASM interrupt, but without the hassle. With on interrupt, the problem is you are limited to only seeing the INT after each PBP instruction. So for code with a pause for instance, the interrupt won't fire until after the pause is done.

[cncmachineguy]

Tom, for some reason, I am having trouble pisturing you magnet/sensor setup. Is it possible for the magnet to fire the int, but none of the 3 IF conditions are met? Is there anyway you can make a quick sketch showing the relationship of the magnets sensors, and pully? Doesn't need to be fancy, just a visual. Or even a picture might do it.

[TDuman]

Hi Bert,
Attached is sketch I drew in Paint.
Regards
Tom

[cncmachineguy]

That helps a ton.

so I don't know if my approach is flawed, I have something wrong in the code, or there is some hardware problem.

It may be a little of each. But first lets attack the hardware. I don't think you need the "R" signal. you can get the counts from the A or B. Now, the reason I want to drop it, besides making the code a little simpler, is I fear you may have some overlap in the fields. This could be why you get the wierd stuff with rising or falling edge trigger. Do you have access to a scope to actually watch B and R to see in B dies before R rises?

[TDuman]

Hi Bert,
I could have sworn that I replied to your last post last week.
I fact, I was anxiously awaiting your response and was checking 2 or three times a day, but never got one.
Then on Friday, I checked this forum again, and my reply was not there. (Maybe it was never there, but I would have sworn that I did see it)
Anyway, since there was no response, I figured you lost interest.
My respose to your last post July 26 was the following (as best as I can remember):

We have put the contraption on a scope and can cleanly see that the pulse finishes before the next one starts. The voltage on all pins is 5 volts and drops to zero when the magnet passes the sensor.
And besides, I am turning the wheel very, very slowly, to watch what I get in the interrupt registers.
I believe that I do need all three signals to tell which direction the wheel is turning. With only A & B, the sequence of signal would always be A-B-A-B-A-B, now matter which direction the wheel is traveling.
With three signals A,B, & R, The sequence would be A-B-R-A-B-R-A-B-R going in one direction, but A-R-B-A-R-B-A-R-B in the reverse direction.

We have an older version of this same contraption, that seems to work perfectly. However, I can't get my hands on the source code to see how it was done. That model was before my time, years ago.

regards
Tom

[cncmachineguy]

I usually never lose intrest in this type stuff. I have come to notice more often then not the OP will either resolve their problem or give up without ever posting about it. Thanks for checking again, I am sorry your post was lost. ANYWAY,

I will have to go back and look at the code again. I must admit I don't remember how I thought you could lose the R, I think I must have been thinking the A & B magnet fields would crossover and be more like a encoder output.

But now we at least know for sure it is not the hardware, so that variable is out of the question. I need to re=read the thread but will post something in a little bit.

[cncmachineguy]

Alright first things first. If it were me, I would put the timer check first, that way if an interrupt occurs, and it is not the timer, it MUST be a portb interrupt. That way you can lose the big 3 way or check.

Next up on my chopping block are the 3 IF's. is there any way for more then 1 int flag to be high at the same time? and if there is, you will do nothing in the ISR because of the AND checks. I would think you will have the correct results by simply checking each flag, 1 at a time and doing whatever there. These 2 things may not improve your current problem, but will certainly have bearing when that wheel gets going.

Now last, I realize the LCD part is just while debugging, but put it before the b port checks. this way you will do the "long" time stuff, then inc the counts based on int flags, then clear the flags. As it now, there is a possibility the int gets called for "b", by the time you get to checking, R flag is now set also. both counts should get updated but they won't. then you clear all 3 flags, so 1 could get missed.

Thats all for now, See if any of this helps.

[mackrackit]

I have not studied the problem but I will put in a couple of things.
1- ON INTERRUPT is not the best for time sensitive operations, ASM types are what you need. This is because ON INTs will not happen instantaneously, they will wait for other things to finish.

2- No matter what type of interrupt you use, you will want to get in and out of the ISR as quick as possible. Set a flag or set a AR while in the ISR and act on that in the main routine.

ASM interrupts are a bit difficult at times so Darrel gave us Instant Ints.
http://www.picbasic.co.uk/forum/show...ant+interrupts

[TDuman]

Hi Bert,
No, I don't mind.
As a newcomer, I was hesitant to put too much in the post.
I hope you can find whatever flaw I may have. I did a google search for DT_INT. I had seen it before when I was scouring the i-net for articles relating to my problem. I had taken note of it and saved a link for possible future use. It may improve my code and cpu time, but at this point, do see a flaw in the existing approach I am taking? Should this work?
Regards
Tom
PS: I see your next post requesting sketch as I am posting this reply, I'll post a sketch in my next reply