In SX Microcontrollers, SX/B Compiler and SX-Key Tool, BPM-Work wrote:

This may be due to the quadrature encoder I am using but here it goes...  :\
 

When using the below code from the help file (I removed the display code) when I WATCH the encValue using

debug, or even putting encValue out to a port with leds, the count always increments and decrements by 4 decimals. When I turn the encoder VERY slowly, between clicks(my encoder has 32 lock positions) it will show the first two bits momentarily, but they dissappear...

So I turn my encoder one click, and it counts 4, and if I turn it again, 8.  Then I turn it back, and it counts back to 4, turn it once more back, then counts 0.

 

Is this code somehow counting too many pulses from my quadrature encoder?

The encoder I am using is a HRPG-AD32-#13C [url]http://www.avagotech.com/assets/downloadDocument.do?id=610[/url]

 

And code suggestions on how to deal with this?

 

 

[code]

' -------------------------------------------------------------------------
' Device Settings
' -------------------------------------------------------------------------

DEVICE          SX28, OSC4MHZ, TURBO, STACKX, OPTIONX
FREQ            4_000_000
ID              "ENCODER"

' -------------------------------------------------------------------------
' IO Pins
' -------------------------------------------------------------------------

EncPort         VAR     RA                      ' encoder port
TRIS_Enc        VAR     TRIS_A

' -------------------------------------------------------------------------
' Constants
' -------------------------------------------------------------------------

MaxVal          CON     100

' -------------------------------------------------------------------------
' Variables
' -------------------------------------------------------------------------

encCheck        VAR     Byte
encOld          VAR     Byte                    ' previous encoder bits
encNew          VAR     Byte                    ' new encoder bits
encValue        VAR     Byte                    ' encoder value

tmpB3           VAR     Byte

' -------------------------------------------------------------------------
  INTERRUPT
' -------------------------------------------------------------------------

' Runs every 64 uS @ 4 MHz (no prescaler)

ISR_Start:
  encNew = EncPort & %00000011                  ' get econder bits
  tmpB3 = encOld XOR encNew                     ' test for change
  IF tmpB3 > 0 THEN                             ' change?
    encOld = encOld << 1                        ' adjust old bits
    encOld = encOld XOR encNew                  ' test direction
    IF encOld.1 = 1 THEN
      IF encValue < MaxVal THEN                 ' if max, no change
        INC encValue                            ' increase value
      ENDIF
    ELSE
      IF encValue > 0 THEN                      ' if 0, no change
        DEC encValue                            ' decrease value
      ENDIF
    ENDIF
    encOld = encNew                             ' save last input
  ENDIF
 
ISR_Exit:
  RETURNINT

' =========================================================================
  PROGRAM Start
' =========================================================================

' -------------------------------------------------------------------------
' Subroutine Declarations
' -------------------------------------------------------------------------


' -------------------------------------------------------------------------
' Program Code
' -------------------------------------------------------------------------

Start:
  encNew = EncPort & %00000011                  ' read encoder pos
  encOld = encNew                               ' copy
  encValue = 0                                  ' clear value
  OPTION = $88                                  ' interrupt, no prescaler

Main:
  
GoTo Main

' -------------------------------------------------------------------------
' Subroutine Code
' -------------------------------------------------------------------------
[/code]

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