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

I haven't tested this (no hardware eh?) but it compiles.

This saves a couple bytes, at the cost of using a second temp in the interrupt. Since you have both encoders on the same port, there is no reason you can't save both channels in one oldbyte and save space.  You can also do the shifting and xoring of both channels at the same time, since you only look at one bit of the results to determine direction.
This also lends itself to extension to 4 channels on one 8 bit port, by adding the appropriate bit tests for additional channels.  Or make the thing a loop with a bit mask to test the change and direction bits and increment or decrement the positions in an array.

[code]

[code]DEVICE          SX28, OSC4MHZ, TURBO, STACKX, OPTIONX
FREQ            4_000_000,4_480_000
ID  "ENCODER" 

[code]EncPort         VAR     RA                      ' encoder port
TRIS_Enc        VAR     TRIS_A
MaxVal          CON     255

[code] 
'encCheck VAR Byte
EncodersOld     VAR     byte                  
EncodersNew     VAR     byte                   
Encoder_A_Count VAR     byte  
Encoder_B_Count VAR     byte  
tmpB1           VAR     byte
tmpB2           VAR     Byte
tmpB3           VAR     Byte
 
' =========================================================================
INTERRUPT
' =========================================================================
' Runs every 64 uS @ 4 MHz (no prescaler)
ISR_Start:
 EncodersNew = EncPort
 TmpB1 = EncodersOld XOR EncodersNew ' compare old with new
                                     ' to work out which channels have changed
 TmpB2 = TmpB1 << 1   ' make single bit that shows change on A or B phase
 TmpB1 = TmpB1 OR TmpB2
 EncodersOld = EncodersOld << 1  ' make direction bits by comparing old A with new B
 EncodersOld = EncodersOld XOR EncodersNew ' xor old A with new B
 IF TmpB1.3 = 1 THEN
     IF EncodersOld.3 = 1 THEN 
   INC Encoder_A_Count                          
     ELSE
   DEC Encoder_A_Count                           
      ENDIF
  ENDIF
' ========================================================================= 
 IF tmpB1.1 = 1 THEN                  
      IF EncodersOld.1 = 1 THEN 
     INC Encoder_B_Count                          
      ELSE
   DEC Encoder_B_Count                           
      ENDIF
   ENDIF
 EncodersOld=EncodersNew
[code]'ISR_Exit:
  RETURNINT                                    
[code]' =========================================================================
  PROGRAM Start
' =========================================================================
 
Start:
                              
 
  EncodersNew = EncPort
  EncodersOld = EncodersNew
  Encoder_A_Count = 0 
  Encoder_B_Count = 0 
   
  OPTION = $88                                  ' interrupt, no prescaler
Main:
  DO
 
 ShiftOut RC.7,RC.6,1,Encoder_A_Count
 Pulsout RC.0,1 
  
 ShiftOut RC.7,RC.6,1,Encoder_B_Count
 Pulsout RC.0,1  
  
   
   
  LOOP
[/code]

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