Quad Encoder Problem

[RossWaddell]

I tried this but nothing happens - the display changes erratically with encoder movement and only really goes up or down by 1:

#DEFINE USE_CUI_ROTARY_ENCODER  ; comment out if using Grayhill rotary encoder
                                ; which triggers an interrupt only once per detent

' Enable interrupts on RPM control now that motors are fully spun up
INTCON   = %10001000        ' Global int enabled, IOCI enabled, 
                            ' INTF flag bit 0 clr, IOCI flag bit 0 clr

#IFDEF USE_CUI_ROTARY_ENCODER
    IOCAP.1  = 1                ' Enable positive (rising edge) change, PORTA.1
'   The CUI encoder goes thru a full quad cycle with 1 detent turn,
'     so only need to capture 1 edge (A channel, rising)

'   CH A
'   ====
'       ------        ------
'      |      |      |      |
'      |      |      |      |
'   ---        ------        ------

'   CH B
'   ====
'          ------        ------
'         |      |      |      |
'         |      |      |      |
'   ------        ------        ---

'   Detent markers
'   ==============
'   |               |              |
'   |               |              |

'   If interrupt is triggered, it means A had a rising edge:
'           If B = 0 Then CW
'           If B = 1 Then CCW
#ELSE
    ' For Grayhill encoder, 1 detent triggers only 1 edge
    IOCAP.0  = 1                ' Enable positive (rising edge) change, PORTA.0
    IOCAP.1  = 1                ' Enable positive (rising edge) change, PORTA.1
    IOCAN.0  = 1                ' Enable negative (falling edge) change, POARTA.0
    IOCAN.1  = 1                ' Enable negative (falling edge) change, PORTA.1
    IOCAF.0  = 0                ' Clear interupt-on-change flag
    IOCAF.1  = 0                ' Clear interupt-on-change flag
#ENDIF

@ INT_ENABLE  IOC_INT       ; Interrupt-on-Change interrupt

Main:
    ' Check if motor RPM has changed
    IF MotorRPM <> Old_RPM Then
        Old_RPM = MotorRPM
        GOSUB ChngMotorHPWM
    EndIF   
  
    If ValueDirty = 1 THEN
        TimeToSave = TimeToSave - 1
        If TimeToSave = 0 THEN           ' Time to save ?
            WRITE EE_MotorRPM, MotorRPM
            
            ValueDirty = 0               ' Clear the flag

            #IFDEF USE_LCD_FOR_DEBUG
                HSEROUT [LCD_INST, LCD_CLR]
                pause 5
                HSEROUT ["Saved RPM=", DEC MotorRPM, "  ", 13, 10] ' Send text followed by carriage return and linefeed
            #ENDIF
        ENDIF
    ENDIF
 
    GOTO Main

' ***************************************************************
' [IOC - interrupt handler]
' ***************************************************************
RotEncAdjust:
    #IFDEF USE_CUI_ROTARY_ENCODER
        IF PORTA.0 = 0 THEN
            RotEncDir = 1                 ; CW rotation if B channel is 0
        ELSE
            RotEncDir = 0                 ; CCW rotation
        ENDIF
    #ELSE
        New_Bits = PORTA & (%00000011)
    
        IF New_Bits = Old_Bits Then DoneRotEnc
    
        RotEncDir = New_Bits.1 ^ Old_Bits.0
    #ENDIF

    IF RotEncDir = 1 Then
        ; CW rotation - increase speed but only to a max of 'MaxDuty'
        IF MotorRPM < MaxDuty then MotorRPM = MotorRPM + 1
    Else
        ' CCW rotation - decrease speed to a min of 0
        IF MotorRPM > 0 Then MotorRPM = MotorRPM - 1
    EndIF

    ValueDirty = 1                  ; Set dirty flag
    TimeToSave = 50000              ; Set value to begin countdown to EEPROM save

DoneRotEnc:
    Old_Bits = New_Bits

    IOCAF.0 = 0                     ' Clear interrupt flags
    IOCAF.1 = 0

@ INT_RETURN

(I left out the rest of the code)