IOC on pin going HIGH and LOW

[Demon]

PIC 16F18877

Custom DT_INTS-14.bas entry:

;---[16F1885x7x]------------------------------------------------------------
; #define IOC_INT      INTCON,IOCIF, INTCON,IOCIE  ;-- Int On Change
  #define IOC_INT      PIR0,IOCIF, PIE0,IOCIE      ;-- Int On Change       *

Will turn LED on when pressed, and off when released:

#CONFIG
    __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON
    __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF
    __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_ON & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC
    __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF
    __config _CONFIG5, _CP_OFF & _CPD_OFF
#ENDCONFIG

DEFINE OSC 32

include     "C:\PBP Includes\DT_INTS-14_16F1885x-7x.bas"
include     "C:\PBP Includes\ReEnterPBP.bas"

ASM
INT_LIST  macro      ;IntSource,  Label,     Type, ResetFlag? 
        INT_Handler   IOC_INT,    _MyIOCinterrupts,    PBP,  yes
    endm
    INT_CREATE                      ;Creates the interrupt processor
ENDASM

'--------------------------------------------------------------------------
'                           Controlled by DT-INTS
'INTCON = %10000000
'           bit 7   GIE         Global Interrupt Enable bit
'                                   1 = Enables all active interrupts
'           bit 6   PEIE        Peripheral Interrupt Enable bit
'           bit 5-1     Unimplemented: Read as ‘0’
'           bit 0   INTEDG      Interrupt Edge Select bit
'PIE0 = %00010000    ' PERIPHERAL INTERRUPT ENABLE REGISTER 0
'           bit 7-6 Unimplemented: Read as ‘0’
'           bit 5 TMR0IE: TMR0 Overflow Interrupt Enable bit
'           bit 4 IOCIE: Interrupt-on-Change Interrupt Enable bit
'                                   1 = Enables the IOC change interrupt
'           bit 3-1 Unimplemented: Read as ‘0’
'           bit 0 INTE: INT External Interrupt Flag bit
'--------------------------------------------------------------------------

IOCCP = %00010000   ' INTERRUPT-ON-CHANGE PORTC POSITIVE EDGE REGISTER
'           bit 7-0 IOCCP<7:0>  Interrupt-on-Change PORTC Positive Edge Enable bits
'                                   1 = Interrupt-on-Change enabled on the pin
'                                       for a positive-going edge. IOCCFx bit
'                                       and IOCIF flag will be set upon detecting an edge.

IOCCN = %00010000   ' INTERRUPT-ON-CHANGE PORTC NEGATIVE EDGE REGISTER
'           bit 7-0 IOCCP<7:0>  Interrupt-on-Change PORTC Negative Edge Enable bits
'                                   1 = Interrupt-on-Change enabled on the pin
'                                       for a Negative-going edge. IOCCFx bit
'                                       and IOCIF flag will be set upon detecting an edge.

ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

TRISA = %00000000
TRISB = %00000000
TRISC = %00010000
TRISD = %00000000
TRISE = %00000000

PushSwitch      VAR PortC.4
InterruptLED    VAR LatC.2

ButtonWasPressed VAR byte

    Pause 500                                       ' Let PIC stabilize
    InterruptLED = 0
    ButtonWasPressed = 0
    
@ INT_ENABLE IOC_INT

    IOCCF.4 = 0

Mainloop:

    if ButtonWasPressed = 1 then                    ' Check flag
        InterruptLED = 1
    else
        InterruptLED = 0
    endif
    
    goto mainloop

MyIOCinterrupts:

    if IOCCF.4 = 1 then
        if ButtonWasPressed = 1 then                ' toggle flag
            ButtonWasPressed = 0
        else
            ButtonWasPressed = 1
        endif
        IOCCF.4 = 0
    endif
@ INT_RETURN
end

[Demon]

Using the IOC logic above, along with Bourns debounce circuit (10K/0.01uF) followed by a 74HC14, these are the signal speeds I was able to get using an ordinary pushbutton and EC11-type rotary encoder:



Switch:
33.9msec ON
146.2msec ON to ON

Encoder:
2.13msec ON
3.01msec ON to ON


To keep things in perspective, I added a LED toggle in MainLoop.

Heartbeat:
2.12usec ON
4.75usec ON to ON

[richard]

followed by a 74HC14,

why the redundant extra schmitt trigger?

in the pic 16F1885x family all input pins are ST by default unless you clear the INPUT THRESHOLD CONTROL bit in the INLVLx register

[Demon]

why the redundant extra schmitt trigger? ...

Because I started development using a 16F1937 and didn't notice the ST on the 16F18877.

(runs over to the datasheet)



EDIT: Wow! That PIC is amazing; every pin has ADC and ST. That's gonna help bring costs down from those 74HC14 ICs.

[richard]

Because I started development using a 16F1937

unfortunately one of the very few enhanced core pic chips without INPUT THRESHOLD CONTROL.

[Ioannis]

193x was a nice chip in its time but now comparing to 188xx seems so old...!

And I have many in stock...

Ioannis

[Demon]

Registers associated with Interrupts are in Table 7-1 on p. 153:




From my observations, you need 2 entries in the DEFINES for 16F:

- Result bit,
- Enable bit.


#DEFINE {DT-INT interrupt NAME} {result flag REGISTER}, {result flag bit}, {enable bit REGISTER}, {enable bit}

For example:
#DEFINE IOC_INT PIR0,IOCIF, PIE0,IOCIE

[Demon]

I keep the IOC flags right alongside the pin definitions (this is a EC11-type rotary encoder; 2 shafts + pushbutton):

;--- Setup pins ----------------------------------------------------------------

COM1_MHz_WiperA             var PortA.2         ' Outer
IOC_COM1_MHz_WiperA_flag    var IOCAF.2         '       IOC flag
COM1_MHz_WiperB             var PortA.3         ' Outer
IOC_COM1_MHz_WiperB_flag    var IOCAF.3         '       IOC flag
COM1_KHz_WiperA             var PortA.0         ' Inner
IOC_COM1_KHz_WiperA_flag    var IOCAF.0         '       IOC flag
COM1_KHz_WiperB             VAr PortA.1         ' Inner
IOC_COM1_KHz_WiperB_flag    var IOCAF.1         '       IOC flag
COM1_SPST                   var PortA.4         ' Swap
IOC_COM1_SPST_flag          var IOCAF.4         '       IOC flag

It makes it easier (for me) to make sure things are connected exactly where I think they are. It's also much easier to move things about on the pins.