Need interrupt example(s)

[fisyon]

hi,
i am using pic16f628a to drive a step motor. portb.4 to portb.7 goes to coils.
it has 4 switches to control direction, step durations and limiting. (portb.0 to portb.3)
it works fine with my novice code but i have to press and hold ~5-6 seconds to read status of the switches. because i have to wait for all 4 steps (~1,7 secs per step, used "wait" routines).

i thought i need to use interrupts but very confused about usage. (only example in the help file was about a timer interrupt)

i need clear examples (as for dumps as possible :P) if there is a software solution.

[mmotte]

This page has helped me before.

http://gcbasic.sourceforge.net/newfiles/help/oninterrupt.htm

PORTBChange would be my first look. Put the buttons here on portB and move you outputs.

GL
M

[mmotte]

16F628 has portb interrupt capable on portB.4 to PortB.7.

This code operated a motor on my telescope using a h bridge chip
UDN2993

     'A program to run motor

     'Chip model
     #chip 16F886, 4

     'Set the pin directions
     #define RAplus PORTB.2 
     #define RAstop PORTB.3
     #define en1 PORTC.2 
     #define dir1 PORTC.3 
     #define en2 PORTC.4 
     #define dir2 PORTC.5 
       #define decup PORTB.4
     #define decdwn PORTB.5 
     dir PORTC out
     dir PORTA in
     dir PORTB in
     #define PWM_Out1 PORTC.2       
     #define PWM_Out2 PORTC.4

     MOVLW 0x3c 
     MOVWF IOCB  ' selects pin that will interrupt on portb

     On Interrupt PORTBChange Call movefast
     'Main routine
     Start:

        wt = ReadAD(AN0)  'interval value

        SET dir1 OFF    ' run motor for a couple secs
        'SET en1 ON
        PWMOut 1, 100, 5
        'wait 1 s
        SET dir1 Off
        SET en1 OFF

        for ijk=0 to wt   ' wait analog value secs  0-255

        wait 10 10ms

        NEXT

     goto Start

     sub movefast
        if RAplus = 0 then
            DO UNTIL RAplus = 1
            SET dir1 OFF    ' run RA motor 
            PWMOut 1, 100, 5
            loop        
        end if

        if RAstop = 0 then 
            DO UNTIL RAstop = 1
            SET dir1 ON ' run motor for a couple secs
            PWMOut 1, 100, 5
            loop
        end if

             if decup = 0 then 
            DO UNTIL decup = 1
            SET dir2 OFF    ' run motor for a couple secs
            PWMOut 2, 100, 5
            loop
        end if
        if decdwn = 0 then
            DO UNTIL decdwn = 1
            SET dir2 ON ' run motor for a couple secs
            PWMOut 2, 100, 5
            loop
        end if

     End Sub    

It gives an example of interrupt PortBChange.
RA is ascension Hour angle , dec declination

I am sorry but I cannot keep the indents in the formatting. yes i read help
GL
M

[fisyon]

thanks for the replies.
actually i am using that step motor on a single arm barn door tracker.
so, as i understand "portbchange" can call a subroutine.

what if some portB pins changes as output? will that cause a conflict?

as i understand:
...
on interrupt portbchange call swchange
...
swchange
...
end sub
is this usage enough?

if so i really don't get these lines:

...
MOVLW 0x3c
MOVWF IOCB ' selects pin that will interrupt on portb
...

[mmotte]

IOCB is a register for Interrupt on change portB in the 16f886 that allows you to select which bit(s) you want to cause the interrupt. On the 16F628A that register(96) is not implemented so I assume portB.4 5 6 or 7 change will cause the interrupt. No register IOCB then you don't need these two lines.

Also I think you could use portB.0-3 for other purposes like outputs

73
M

[mmotte]

fisyon,
I was working on a barndoor to track the stars last month. I used a geared down 4096 stepper from china off of ebay. GCbasic into a 16F886. Finally got the timing pretty good and could take 10 minute exposures. Then it turned cold and windy and cloudy.
73
M

[fisyon]

your tracker looks nice, congratulations.

i am using 48 stepper which is very fast for the tracker(the length of the arm=~210mm), then i have to drive very slow (~1750 miliseconds per step).
i can't see polaris because of buildings then i am using "blind" polar alignment. i have ~5 minutes without star trails which is more than enough for DSLR kit lens (18-55 mm at 55 mm). clouds are always pain in the butt :)

however, my problem is controlling the pic via switches. it doesn't matter which pin will cause the interrupt (Portb0-3).
unfortunately i can't find any sample about interrupt with switches.
of course i am talking about GCBasic examples.

[mmotte]

/~~~~
::::GCBasic
'A program to Run a 4096 step geared step motor on a 10-32 threaded rod
' for a "barn Door" tracker to hold a camera and track the stars
'by Mike Otte
'2013

'Chip model
#chip 16F886, 8

dim Full(5)
Full(0) = b'00000110'
Full(1) = b'00000011'
Full(2) = b'00001001'
Full(3) = b'00001100'

dim RFull(5)
RFull(3) = b'00000110'
RFull(2) = b'00000011'
RFull(1) = b'00001001'
RFull(0) = b'00001100'

' my momentary switches
#define Home PORTC.0
#define RAstop PORTC.1
#define RAplus PORTC.2
#define limit PORTC.3
'define PORTC upper 4 bits for adjusting the time in additional millisec / step

'Set the pin directions
dir PORTB out
dir PORTC IN
' i am not using interrupt because this motor steps fast
'On Interrupt PORTBChange Call buttons

wttm = 17 'wait time was 25 msec
wtmodify= PORTC
wtmodify = wtmodify AND 0xf0 ' mask off the upper four bits
rotate wtmodify right simple 'shift them to the lower four bits
rotate wtmodify right simple ' i put pullups and board withjumper pins to act as switches
rotate wtmodify right simple
rotate wtmodify right simple
wttm = wttm + wtmodify ' add or subtract for tuning delay from portc upper four bits
' wttm (wait time) now has the total value
PortB = 0 'initialize
myj=0
wait 1 s
'Main routine

Start:
myStep = myj mod 4
thisStep = Full(myStep)
PortB = thisStep
wait wttm ms
myj++
gosub buttons

goto Start

sub buttons
if RAplus = 0 then ' these were going to make it go faster or slower
DO UNTIL RAplus = 1
myStep = myj mod 4
PortB = Full(myStep)
wait 7 ms
myj++
loop
end if

if RAstop = 0 then   ' but i don't use these two switches
  DO UNTIL RAstop = 1
    myStep = myj mod 4
        PortB =  RFull(myStep)
         wait  7 ms
    myj++
   loop
end if

'*
'I really only use the following two switches
'"home" switch sends the barn door towards home (closed limit)
' the "limit" stops it when it get home
'and returns it to going forward again
'**
if home = 0 then
DO UNTIL limit = 0
myStep = myj mod 4
PortB = RFull(myStep)
wait 2 ms
myj++
loop
end if

End Sub
~~~~/

this is the code for my barndoor controller.

If you use interrupts for switches your switches must be on portB inputs portB.4, portB.5, portB.6,and or portB.7

Your motor must be on some other pins

73
M

[fisyon]

so, as i understand, i have to change my circuit completely... :(

it's worthless to do that at this moment. maybe later with a better step motor...

thanks a lot for your help

[Max]

I have problem too with interrupt .... i am using 16F8768A and interupt on port B doesn' work. the LED is in PORTA.0 and switch is in PORTB.2 and iterrupt is never generated .

where is the problem ???

---

;Chip Settings
#chip 16F876A,20
#config OSC=HS

Dir PORTA.0 out  ' LED
Dir PORTB.2 in   ' SWITCH

On Interrupt PORTBChange Call LED

inizio:
goto inizio

Sub LED
    PulseOut PORTA.0, 1 sec
End Sub

---

please help :)

[mmotte]

Please read the PIC16F87Xa data sheet.

"Four of the PORTB pins, RB7:RB4, have an interrupt-
on-change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt-
on-change comparison).
"

Also read,
"clear the
interrupt in the following manner:
a) Any read or write of PORTB. This will end the
mismatch condition.
b) Clear flag bit RBIF.
"
I am not sure if GCBasic compiler when using this syntax automatically clears RBIF but I think it does?

73
M
This should have been in a new thread.