Change On Interrupt, PIC16F884

[elec_mech]

One more question: How about detecting multiple switches with interrupt-on-change? I've tried the modified code below as well as the commented out code on its own. This works, but not reliably. I'm using those momentary red square switches from RadioShack and the LEDs only change about half the time, i.e., the program isn't detecting the button press. I've tried pressing the switches hard (fully down) quickly, but with the same hit rate of half. If I press and hold each button for a second or two, it works fine, but I don't want to force the user to press and hold a switch to do something. I tried playing with the debounce times and even adding a ceramic capacitor, 0.1uF and 0.01uF across the switch contacts with no luck. I tried searching the forum, but the only interrupt examples I've come across are for single button applications. Any suggestions?

INCLUDE "modedefs.bas"
PORTA = $00 ' Set all port a pins to low
PORTB = $00 ' Set all port b pins to low
PORTC = $00 ' Set all port c pins to low
PORTD = $00 ' Set all port d pins to low
PORTE = $00 ' Set all port e pins to low

asm ; The following code is assembly, not Basic
__CONFIG _CONFIG1, _INTOSCIO & _WDT_OFF & _PWRTE_ON & _CP_OFF & _BOR_OFF & _IESO_OFF & _FCMEN_OFF & _LVP_OFF
; Use internal oscillator & make both, OSC pins I/Os, turn off watchdog timer, enable Power-up timer,
; code protection off, brown-out off, disable switch over mode, turn off failsafe monitor,
; low voltage programming off
endasm ' End assembly code

ADCON0.0 = 0 ; Make all analog pins digital I/Os
CM1CON0.7 = 0 ; Disable comparator C1
CM2CON0.7 = 0 ; Disable comparator C2
OSCCON.6 = 1 ; Set the internal oscillator to 8MHz
OSCCON.5 = 1 ; Set the internal oscillator to 8MHz
OSCCON.4 = 1 ; Set the internal oscillator to 8MHz
WDTCON.0 = 0 ; Disable the watchdog timer
ANSEL = %00000000 ; Set all analog pins on port a to digital I/O
ANSELH = %00000000 ; Set all analog pins on port b to digital I/O

define OSC 8 ' Tell the program the oscillator is running at 8 MHz
TRISA = %00000000 ' Make all port a pins outputs
TRISB = %00001111 ' Make port b pins 0-3 inputs and the rest as outputs
TRISC = %00000000 ' Make all port c pins outputs
TRISD = %00000000 ' Make all port d pins outputs
TRISE = %00000000 ' Make all port e pins outputs
PORTA = $00 ' Set all port a pins to low
PORTB = $00 ' Set all port b pins to low
PORTC = $00 ' Set all port c pins to low
PORTD = $00 ' Set all port d pins to low
PORTE = $00 ' Set all port e pins to low
'Variables**************************************** ************************************************** *
b0 VAR byte ' Required byte variable for toggle button
'************************************************* ************************************************** *
INITIALIZE: ' Initialize Routine
INTCON.0 = 0 ' Clear the interrupt-on-change flag
On Interrupt goto Halt ' Once an active interrupt port is enabled, go to the Halt routine
INTCON = %10001000 ' Enable global interrupts, Enable interrupt-on-change on Port b
IOCB = %00000011 ' Enable interrupt-on-change on RB0-RB3
PORTE.1 = 0 ' Make sure LED on PORTE.1 is off
PORTE.2 = 0 ' Make sure LED on PORTE.2 is off
GOTO MAIN ' Go to Main routine
'************************************************* ************************************************** *
MAIN:
HIGH PORTE.0
PAUSE 500
LOW PORTE.0
PAUSE 500
GOTO MAIN
'*************************************************
DISABLE ' do NOT place interrupt checking code below
Halt: ' Halt Routine
IF PORTB.0 = 0 THEN
WHILE PORTB.0=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
HIGH PORTE.1
LOW PORTE.2
ENDIF
IF PORTB.1 = 0 THEN
WHILE PORTB.1=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
LOW PORTE.1
HIGH PORTE.2
ENDIF

' IF PORTB.0 = 0 THEN
' ' PAUSE 20
' ' IF PORTB.0 = 0 THEN
' HIGH PORTE.1
' LOW PORTE.2
' ' ENDIF
' ENDIF
'
' IF PORTB.1 = 0 THEN
' ' PAUSE 20
' ' IF PORTB.1 = 0 THEN
' LOW PORTE.1
' HIGH PORTE.2
' ' ENDIF
' ENDIF

INTCON.0 = 0 ' Clear the interrupt-on-change flag
RESUME ' Go to Main routine
ENABLE ' Enable all active interrupts

[Pic_User]

Hi elec_mech,
Posting code directly into the text portion of the forum makes it difficult to follow.

[code] paste your code here [/code]

One step better but a lot more work:

Show us your Colors.

define osc 8 ' tell the program the oscillator is running at 8 mhz

4.16. DEFINE may be used to change the predefined oscillator value...
These definitions must be in all upper case, exactly as shown.
If not, the compiler may not recognize them.
No error message will be produced for defines the compiler does not recognize.

DEFINE OSC 8

-Adam-

[elec_mech]

Adam,

I see what you mean with the DEFINE, oops! Thanks for the catch. I see what you mean with colors. Is this better?

INCLUDE "modedefs.bas"
PORTA = $00 ' Set all port a pins to low
PORTB = $00 ' Set all port b pins to low
PORTC = $00 ' Set all port c pins to low
PORTD = $00 ' Set all port d pins to low
PORTE = $00 ' Set all port e pins to low

asm ; The following code is assembly, not Basic
__CONFIG _CONFIG1, _INTOSCIO & _WDT_OFF & _PWRTE_ON & _CP_OFF & _BOR_OFF & _IESO_OFF & _FCMEN_OFF & _LVP_OFF
; Use internal oscillator & make both, OSC pins I/Os, turn off watchdog timer, enable Power-up timer,
; code protection off, brown-out off, disable switch over mode, turn off failsafe monitor,
; low voltage programming off
endasm ' End assembly code

ADCON0.0 = 0 ; Make all analog pins digital I/Os
CM1CON0.7 = 0 ; Disable comparator C1
CM2CON0.7 = 0 ; Disable comparator C2
OSCCON.6 = 1 ; Set the internal oscillator to 8MHz
OSCCON.5 = 1 ; Set the internal oscillator to 8MHz
OSCCON.4 = 1 ; Set the internal oscillator to 8MHz
WDTCON.0 = 0 ; Disable the watchdog timer
ANSEL = %00000000 ; Set all analog pins on port a to digital I/O
ANSELH = %00000000 ; Set all analog pins on port b to digital I/O

DEFINE OSC 8 ' Tell the program the oscillator is running at 8 MHz
TRISA = %00000000 ' Make all port a pins outputs
TRISB = %00001111 ' Make port b pins 0-3 inputs and the rest as outputs
TRISC = %00000000 ' Make all port c pins outputs
TRISD = %00000000 ' Make all port d pins outputs
TRISE = %00000000 ' Make all port e pins outputs
PORTA = $00 ' Set all port a pins to low
PORTB = $00 ' Set all port b pins to low
PORTC = $00 ' Set all port c pins to low
PORTD = $00 ' Set all port d pins to low
PORTE = $00 ' Set all port e pins to low
'Variables**************************************** ************************************************** *
b0 VAR byte ' Required byte variable for toggle button
'************************************************* ************************************************** *
INITIALIZE: ' Initialize Routine
INTCON.0 = 0 ' Clear the interrupt-on-change flag
On Interrupt goto Halt ' Once an active interrupt port is enabled, go to the Halt routine
INTCON = %10001000 ' Enable global interrupts, Enable interrupt-on-change on Port b
IOCB = %00000011 ' Enable interrupt-on-change on RB0-RB3
PORTE.1 = 0 ' Make sure LED on PORTE.1 is off
PORTE.2 = 0 ' Make sure LED on PORTE.2 is off
GOTO MAIN ' Go to Main routine
'************************************************* ************************************************** *
MAIN:
HIGH PORTE.0
PAUSE 500
LOW PORTE.0
PAUSE 500
GOTO MAIN
'*************************************************
DISABLE ' do NOT place interrupt checking code below
Halt: ' Halt Routine
IF PORTB.0 = 0 THEN
WHILE PORTB.0=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
HIGH PORTE.1
LOW PORTE.2
ENDIF
IF PORTB.1 = 0 THEN
WHILE PORTB.1=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
LOW PORTE.1
HIGH PORTE.2
ENDIF

' IF PORTB.0 = 0 THEN
' ' PAUSE 20
' ' IF PORTB.0 = 0 THEN
' HIGH PORTE.1
' LOW PORTE.2
' ' ENDIF
' ENDIF
'
' IF PORTB.1 = 0 THEN
' ' PAUSE 20
' ' IF PORTB.1 = 0 THEN
' LOW PORTE.1
' HIGH PORTE.2
' ' ENDIF
' ENDIF

INTCON.0 = 0 ' Clear the interrupt-on-change flag
RESUME ' Go to Main routine
ENABLE ' Enable all active interrupts

[Pic_User]

Adam,
I see what you mean with the DEFINE, oops! Thanks for the catch. I see what you mean with colors. Is this better?

It is better! But the idea is to copy from your editor, paste into a code box. So the indents and formatting look more like the original. Sometimes the forum changes the formatting. I was not sure the lowercase define was in your original or being changed by the forum. It changes a lot of things “for you” I wish I knew more about PBP to really help you on your real question.
-Adam-

[mister_e]

with code bracket
I type
[code]
i now paste my code here
then i type [/code]

we got

        asm ; The following code is assembly, not Basic
                __CONFIG _CONFIG1, _INTOSCIO & _WDT_OFF & _PWRTE_ON & _CP_OFF & _BOR_OFF & _IESO_OFF & _FCMEN_OFF & _LVP_OFF
                ; Use internal oscillator & make both, OSC pins I/Os, turn off watchdog timer, enable Power-up timer,
                ; code protection off, brown-out off, disable switch over mode, turn off failsafe monitor,
                ; low voltage programming off
        endasm ' End assembly code

        define OSC 8        ' Tell the program the oscillator is running at 8 MHz
        OSCCON.6 = 1        ; Set the internal oscillator to 8MHz
        OSCCON.5 = 1        ; Set the internal oscillator to 8MHz
        OSCCON.4 = 1        ; Set the internal oscillator to 8MHz

        PORTA = $00         ' Set all port a pins to low
        PORTB = $00         ' Set all port b pins to low
        PORTC = $00         ' Set all port c pins to low
        PORTD = $00         ' Set all port d pins to low
        PORTE = $00         ' Set all port e pins to low

        TRISA = %00000000   ' Make all port a pins outputs
        TRISB = %00001111   ' Make port b pins 0-3 inputs and the rest as outputs
        TRISC = %00000000   ' Make all port c pins outputs
        TRISD = %00000000   ' Make all port d pins outputs
        TRISE = %00000000   ' Make all port e pins outputs
        
        ADCON0.0 = 0        ; Make all analog pins digital I/Os
        CM1CON0.7 = 0       ; Disable comparator C1
        CM2CON0.7 = 0       ; Disable comparator C2
        WDTCON.0 = 0        ; Disable the watchdog timer
        ANSEL = %00000000   ; Set all analog pins on port a to digital I/O
        ANSELH = %00000000  ; Set all analog pins on port b to digital I/O
        
        INCLUDE "modedefs.bas"

'Variables*****************************************************************************************
        b0 VAR byte         ' Required byte variable for toggle button


'**************************************************************************************************
INITIALIZE:                 ' Initialize Routine
        INTCON.0 = 0        ' Clear the interrupt-on-change flag
        On Interrupt goto Halt ' Once an active interrupt port is enabled, go to the Halt routine
        INTCON = %10001000  ' Enable global interrupts, Enable interrupt-on-change on Port b
        IOCB = %00000011    ' Enable interrupt-on-change on RB0-RB3
        PORTE.1 = 0         ' Make sure LED on PORTE.1 is off
        PORTE.2 = 0         ' Make sure LED on PORTE.2 is off


'*************************************************************************************************** *
MAIN:
        HIGH PORTE.0
        PAUSE 500
        LOW PORTE.0
        PAUSE 500
        GOTO MAIN


'*************************************************
        DISABLE         ' do NOT place interrupt checking code below
        
Halt:   ' Halt Routine
        IF PORTB.0 = 0 THEN
                WHILE PORTB.0=0 ' wait for button release & end mismatch condition on portb
                WEND
                PAUSE 20        ' Debounce delay
                HIGH PORTE.1
                LOW PORTE.2
                ENDIF
                
        IF PORTB.1 = 0 THEN
                WHILE PORTB.1=0 ' wait for button release & end mismatch condition on portb
                WEND            
                PAUSE 20        ' Debounce delay
                LOW PORTE.1
                HIGH PORTE.2
                ENDIF
       
        INTCON.0 = 0            ' Clear the interrupt-on-change flag
        RESUME                  ' Go to Main routine
        ENABLE                  ' Enable all active interrupts

with colors, following the following thread
http://www.picbasic.co.uk/forum/show...ht=show+colors

we got

<font color="#000000">        <font color="#000080">ASM </font><font color="#008000">; The following code is assembly, not Basic
                </font><font color="#000080">__CONFIG _CONFIG1, _INTOSCIO &amp; _WDT_OFF &amp; _PWRTE_ON &amp; _CP_OFF &amp; _BOR_OFF &amp; _IESO_OFF &amp; _FCMEN_OFF &amp; _LVP_OFF
                </font><font color="#008000">; Use internal oscillator &amp; make both, OSC pins I/Os, turn off watchdog timer, enable Power-up timer,
                ; code protection off, brown-out off, disable switch over mode, turn off failsafe monitor,
                ; low voltage programming off
        </font><font color="#000080">ENDASM </font><font color="#008000">' End assembly code

        </font><font color="#000080">DEFINE </font>OSC 8        <font color="#008000">' Tell the program the oscillator is running at 8 MHz
        </font>OSCCON.6 = 1        <font color="#008000">; Set the internal oscillator to 8MHz
        </font>OSCCON.5 = 1        <font color="#008000">; Set the internal oscillator to 8MHz
        </font>OSCCON.4 = 1        <font color="#008000">; Set the internal oscillator to 8MHz

        </font>PORTA = $00         <font color="#008000">' Set all port a pins to low
        </font>PORTB = $00         <font color="#008000">' Set all port b pins to low
        </font>PORTC = $00         <font color="#008000">' Set all port c pins to low
        </font>PORTD = $00         <font color="#008000">' Set all port d pins to low
        </font>PORTE = $00         <font color="#008000">' Set all port e pins to low

        </font>TRISA = %00000000   <font color="#008000">' Make all port a pins outputs
        </font>TRISB = %00001111   <font color="#008000">' Make port b pins 0-3 inputs and the rest as outputs
        </font>TRISC = %00000000   <font color="#008000">' Make all port c pins outputs
        </font>TRISD = %00000000   <font color="#008000">' Make all port d pins outputs
        </font>TRISE = %00000000   <font color="#008000">' Make all port e pins outputs
        
        </font>ADCON0.0 = 0        <font color="#008000">; Make all analog pins digital I/Os
        </font>CM1CON0.7 = 0       <font color="#008000">; Disable comparator C1
        </font>CM2CON0.7 = 0       <font color="#008000">; Disable comparator C2
        </font>WDTCON.0 = 0        <font color="#008000">; Disable the watchdog timer
        </font>ANSEL = %00000000   <font color="#008000">; Set all analog pins on port a to digital I/O
        </font>ANSELH = %00000000  <font color="#008000">; Set all analog pins on port b to digital I/O
        
        </font><font color="#000080">INCLUDE </font>&quot;modedefs.bas&quot;

<font color="#008000">'Variables*****************************************************************************************
        </font>b0 <font color="#000080">VAR BYTE         </font><font color="#008000">' Required byte variable for toggle button


'**************************************************************************************************
</font>INITIALIZE:                 <font color="#008000">' Initialize Routine
        </font>INTCON.0 = 0        <font color="#008000">' Clear the interrupt-on-change flag
        </font><font color="#000080">ON INTERRUPT GOTO </font>Halt <font color="#008000">' Once an active interrupt port is enabled, go to the Halt routine
        </font>INTCON = %10001000  <font color="#008000">' Enable global interrupts, Enable interrupt-on-change on Port b
        </font>IOCB = %00000011    <font color="#008000">' Enable interrupt-on-change on RB0-RB3
        </font>PORTE.1 = 0         <font color="#008000">' Make sure LED on PORTE.1 is off
        </font>PORTE.2 = 0         <font color="#008000">' Make sure LED on PORTE.2 is off


'*************************************************************************************************** *
</font>MAIN:
        <font color="#000080">HIGH </font>PORTE.0
        <font color="#000080">PAUSE </font>500
        <font color="#000080">LOW </font>PORTE.0
        <font color="#000080">PAUSE </font>500
        <font color="#000080">GOTO </font>MAIN


<font color="#008000">'*************************************************
        </font><font color="#000080">DISABLE         </font><font color="#008000">' do NOT place interrupt checking code below
        
</font>Halt:   <font color="#008000">' Halt Routine
        </font><font color="#000080">IF </font>PORTB.0 = 0 <font color="#000080">THEN
                WHILE </font>PORTB.0=0 <font color="#008000">' wait for button release &amp; end mismatch condition on portb
                </font><font color="#000080">WEND
                PAUSE </font>20        <font color="#008000">' Debounce delay
                </font><font color="#000080">HIGH </font>PORTE.1
                <font color="#000080">LOW </font>PORTE.2
                <font color="#000080">ENDIF
                
        IF </font>PORTB.1 = 0 <font color="#000080">THEN
                WHILE </font>PORTB.1=0 <font color="#008000">' wait for button release &amp; end mismatch condition on portb
                </font><font color="#000080">WEND            
                PAUSE </font>20        <font color="#008000">' Debounce delay
                </font><font color="#000080">LOW </font>PORTE.1
                <font color="#000080">HIGH </font>PORTE.2
                <font color="#000080">ENDIF
       
        </font>INTCON.0 = 0            <font color="#008000">' Clear the interrupt-on-change flag
        </font><font color="#000080">RESUME                  </font><font color="#008000">' Go to Main routine
        </font><font color="#000080">ENABLE                  </font><font color="#008000">' Enable all active interrupts
</font>

Read your datasheet about Interrupt on change. I haven't done myself, but I bet you should read the whole, save it to a variable, then play with this variable.

Probably not a bad idea, to do the same thing before ON INTERRUPT.. read the whole port, save it to a dummy variable, etc.

HTH

[elec_mech]

Alright, I got smart and have an LED coming on whenever the interrupt routine is entered and guess what? The program always goes into the interrupt routine whenever I press a button. The bad news is that the program doesn't seem to be able to determine which switch is pressed fast enough. Again, if I hold the switch down for a second or more, it knows which switch is pressed. But more often than not, I just press the button as anyone would and I see the LED come on indicating the interrupt routine was entered, but the other LEDs don't toggle most of the time. I suspect that the program is dragging somewhere, but I don't know why the program can pick up a change on PORTB but doesn't have the time to determine which input was tripped. Any suggestions? Modified code below.

'************************************************* ************************************************** *
MAIN:
' HIGH PORTE.0
PAUSE 500
LOW PORTE.0
' PAUSE 500
GOTO MAIN
'*************************************************
DISABLE ' do NOT place interrupt checking code below
Halt: ' Halt Routine
HIGH PORTE.0
IF PORTB.0 = 0 THEN
WHILE PORTB.0=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
HIGH PORTE.1
LOW PORTE.2
ENDIF
IF PORTB.1 = 0 THEN
WHILE PORTB.1=0 ' wait for button release & end mismatch condition on portb
WEND
PAUSE 20 ' Debounce delay
LOW PORTE.1
HIGH PORTE.2
ENDIF

INTCON.0 = 0 ' Clear the interrupt-on-change flag
RESUME Main ' Go to Main routine
ENABLE ' Enable all active interrupts

[Bruce]

You have 500mS delays before your interrupt can even be processed. Unless someone
presses & holds a button, it may be quite a long time before you enter your interrupt
handler.

Reduce your pause times by using a loop with PAUSEUS until your 500mS delay period
expires. Then you only have a few uS before PBP will jump to your int handler, and you
can read the whole port in the first line, save it to a variable, then make a decision on
which switch was pressed.

[Charles Linquis]

Just a suggestion - use Darrel Taylor's Instant Interrupts. If you use that, you don't have to worry about PAUSE. The interrupt routine will be entered whenever the button is pushed - even in the middle of a PAUSE routine. In the end, it is a much cleaner solution than ON INTERRUPT GOTO - believe me.