New approach to Rotary Encoder

[Ioannis]

Here is an experiment on Rotary Encoders and a different approach than the standard XOR way.

loop1:
if portb.1=0 then                 'here is switch 1 of the rotary encoder
    counter=counter+1
    goto lcd
endif

if portb.0=0 then                 'here is switch 2 of the rotary encoder
    counter=counter-1
    goto lcd
endif

goto loop1

lcd:
lcdout $fe,$c0,dec5 counter
while (portb.0=0 or portb.1=0):pause 10:wend
goto loop1

The key is the last While/Wend command where it checks for the next pulse comming after the first edge of either switch of the encoder.

Common of the encoder is Low and Pull Up is supposed to be active.

Ioannis

[Mike, K8LH]

Can you refresh our memory and show us an example of "the standard XOR way"?

[Ioannis]

Two examples in the attachments. They use Interrupts though. When I find some spare time I wll try to make the routines work with IOC and DT-INTS too.

Ioannis

[Marin]

Did you try this code with mechanical encoder, or normal optical encoder?

[Ioannis]

That was with mechanical one.

Ioannis

[jefrem]

With use 4 mecanic rotary encoder with this code (pic18f4550) ?

[Ioannis]

I don't see why not. Its fast enough.

Ioannis

[Mike, K8LH]

A question, please? With the following "while" statement, does the program wait there until both encoder pins are high? If so, then you're only detecting one of every four AB transitions when moving continually in one direction, correct?

while (portb.0=0 or portb.1=0):pause 10:wend

[cncmachineguy]

Yes I think you are correct, this will only detect from 3 to 0 or 3 to 2. So it does not count in quadrature mode. It could be modified with a few more while loops to detect when it leaves the current state.

[Ioannis]

I think not since there is OR in the WHILE statement.

Ioannis

[Mike, K8LH]

I think not since there is OR in the WHILE statement.

But doesn't the OR mean that you're stuck in this loop while either A OR B is low? In other words, you can only get out of the loop when both A and B are high?

[Demon]

Yup, as long as one is LOW, it remains in the loop.

Robert

[Ioannis]

Yes it will for the time that either is in LOW state. If there is a possibility that this condition is likely to happn pemanently, then you have other options to choose.

As stated on he first post, that is an interesting experiment of another way (more simple) to do the same task. No-one is forced to accept it. Or use it. Just forget it and you will be just fine.

Ioannis

[Mike, K8LH]

Please forgive me if it seemed that I was complaining. I was just trying to understand how your method worked.

If you're using a rotary encoder with detents as a control, detecting a single AB transition (out of four) between detents is probably preferable. That's how I do it but I use a switch state latch and simple parallel switch state logic to filter out the unwanted switch states.

Your method is simple and elegant. Thank you for sharing with us...

Cheerful regards, Mike

[Ioannis]

No problem Mike. I have to admit that I was a little touchy.

Yes, the idea was to read a mechanical rotary encoder with detents. Sure is better to buffer the port states and then do the processing.

Even better, use interrups to grab the port change and then do whatever you want. More, make a debounce based on interrupts since mechanical switch of the encoder do bounce a little. But this is for more advanced programmers. Maybe later when my related project allows.

Ioannis

[podgycode]

Hello world. I have learnt a lot from lurking these threads so i thought i would try and help someone else out a bit.




All your encoder worries can be over for about 50 pence and if i can get a picture in here i will show you how...........



the thing to realise is that moving along waveform A from left to right the negative edge of A is always when B is low. moving back the other way the negative edge is always when B is high.

the jk flip flop clock input is negative edge triggered and when triggered it feeds the input on J through to Q -- but only if j and k inputs are opposite hence section 1 of the nor gate to invert the signal. j is always opposite to k now. and the clock input always gets triggered right in the middle of the high or low so it never misses.

so, when moving clockwise Q will be high and anticlockwise it will go low.

two other parts of the quad nor gate (2 and 3 above) to produce a hardware XOR on output C and producing the waveform at bottom of screen.

Now all you need to do is feed C into an input that generates interrupts on a negative edge trigger. when the interrupt fires all it has to do is look at the level of D and either add 1 to clockwise total or subtract 1. Thats it. Your programming days are over.

And, all the mushy signal edges and bounce are tidied up too. Lovely solid latched outputs.
And you are going to have to go some to bother them with speed or with slowness.

Not bad for 50p I hope you will agree.

[Heckler]

Hey podgycode...
I have not tried your circuit. I would guess it works as you describe.

What I can't understand is why is this so difficult to do using two PIC pins and some code. Are these rotary encoders so difficult to read using code??

I am struggling with this very thing myself. I have two rotary encoders... one that I have wired up and done some basic testing... one that I have not tried yet.

I have also done quite a bit of searching over on the Parallax Basic Stamp forum, since the basic stamp uses VERY similar language to our PICbasic.

I really would like to use interrupts (DT instant INT's, if possible)

My real problem is TIME. If I only had more of it, I'm sure you all can relate.

Any way, if anyone has some good sample code (that used interrupts) for one to try... that they might be willing to share

[aratti]

Here the code for a rotary optical encoder, using quadrature.
Just connect the Channel A to portB.6 and channel B to portB.7, ground portB.5 and portB.4

Connection for LCD can be found to page 96 of PBP user manual.

include "ALLDIGITAL.pbp"
INCLUDE "DT_INTS-14.bas"        ; Base Interrupt System
'INCLUDE "ReEnterPBP.bas"        ; Include if using PBP interrupts

DEFINE OSC 20

'                       PIC 16F628
' PicBasic program to demonstrate operation of an LCD in 4-bit mode
'          and reading an optical encoder in quadrature
'
' LCD should be connected as follows:
'       LCD     PIC
'       DB4     PortA.0
'       DB5     PortA.1
'       DB6     PortA.2
'       DB7     PortA.3
'       RS      PortA.4 (add 4.7K pullup resistor to 5 volts)
'       E       PortB.0
'       RW      Ground
'       Vdd     5 volts
'       Vss     Ground
'       Vo      20K potentiometer (or ground)
'       DB0-3   No connect


TrisA = 000000
TrisB = 110000
PortB=0

Define LCD_DREG PORTA
Define LCD_DBIT 0
Define LCD_RSREG PORTA
define LCD_RSBIT 4
define LCD_EREG PORTB
define LCD_EBIT 0
define LCD_BITS 4
define LCD_LINES 2
define LCD_COMMANDUS 2000
define LCD_DATAUS 50

Flag                var bit
wsave               VAR BYTE    $70     SYSTEM  ' alternate save location for W 
Q_New               var Byte
Q_Old               var byte
Q_Count             var word


' Set variable value @ startup
          Flag = 0          
         Q_New = 0
         Q_Old = 0
       Q_Count = 0

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, Resetflag?
        INT_Handler    RBC_INT,  _Encoder,   ASM,  yes
    endm
    INT_CREATE                      ; Creates the interrupt processor
ENDASM

@ INT_ENABLE RBC_INT            ; enable external (INT) interrupts


Lcdout $fe, 1                       ' Clear LCD screen
Lcdout "System Ready"               ' Display message
Pause 500                           ' Wait .5 second

Goto Main_Loop

Encoder:
Q_New = PortB.7 + PortB.7 + PortB.6

if Q_Old = 0 then
if Q_New = 2 then Minus_Count
if Q_New = 1 then Plus_Count
endif

if Q_Old = 1 then
if Q_New = 0 then Minus_Count
if Q_New = 3 then Plus_Count
endif

if Q_Old = 3 then
if Q_New = 1 then Minus_Count
if Q_New = 2 then Plus_Count
endif

if Q_Old = 2 then
if Q_New = 3 then Minus_Count
if Q_New = 0 then Plus_Count
endif

goto Q_Skip

Minus_Count:
Q_Count = Q_Count - 1
   Flag = 1
goto Q_Skip

Plus_Count:
Q_Count = Q_Count + 1
   Flag = 1
Q_Skip:
Q_Old = Q_New
 
 
@ INT_RETURN

Main_Loop:   

if Flag = 1 then
Lcdout $fe, 1                    
Lcdout Dec Q_Count
Flag = 0
endif

goto Main_Loop

end

Enjoy

Cheers

Al.

[podgycode]

heckler,
have a look at this:-

' Target PIC : 12F, 16F, 18F
' Hardware : Non specific
' Oscillator : internal or external
' Keywords : ON INTERRUPT
' Description : PICBASIC PRO program to demonstrate use of On Interrupt
' Interrupts in BASIC. Turn LED on. Interrupt on PORTB.0 (INTE) turns LED off.
' Program waits .5 seconds and turns LED back on.

led Var PORTB.7

OPTION_REG = $7f ' Enable PORTB pullups

On Interrupt Goto myint ' Define interrupt handler
INTCON = $90 ' Enable INTE interrupt

mainloop:
High led ' Turn LED on
Goto mainloop ' Do it forever

' Interrupt handler
Disable ' No interrupts past this point
myint:
Low led ' If we get here, turn LED off
Pause 500 ' Wait .5 seconds
INTCON.1 = 0 ' Clear interrupt flag
Resume ' Return to main program
Enable

End

------------------------
the main loop runs and when an interrupt happens the program jumps to the handler called myint. does what is in myint and then returns to resume where it left off in the main loop.

just set the config so your interrupt is enabled that you want to use and put the code to read it in the myint routine. the main loop can do whatever it likes.

what do you think?

[Mike, K8LH]

Connection for LCD can be found to page 96 of PBP user manual.

Do you have a link the that manual, please? I've looked at two different PBP Compiler Manuals so far and neither has a schematic for an LCD interface on page 96...

[Heckler]

@ podgycode... Thanks for your example, but what I meant was I would like to implement a rotary encoder via DT's Instant Interupts. I have used "on interrupt" successfully before to detect push buttons, etc. I have yet to use InstantINT's. I am going to try aratti's example in post #18 above.

@ aratti... could you please clarify a couple of questions regarding your example...

ground portB.5 and portB.4

Why is this necessary?

Q_New = PortB.7 + PortB.7 + PortB.6

What does this line of code do??

TrisA = 000000
TrisB = 110000

I assume these need % in front of the binary number??

I hope this is not considered "hijacking" of this thread... as it still regards implementing Rotary Encoders.
Thanks for your help




example

[Heckler]

@ aratti... one more question

wsave VAR BYTE $70 SYSTEM ' alternate save location for W

could you help me with this line? Is it correct or did the forum software mess it up??

thanks

P.S. Oh yea... disregard this question... I think I see how it works..

Q_New = PortB.7 + PortB.7 + PortB.6 What does this line of code do??

[aratti]

Heckler, yes trisA and trisB need "%" (don't know Why have been removed)

PortB.4 and portB.5 are set as input and never leave an input pin floating.

Wsave is a variable used by DT INT-14.


@Mike K8LH

The PBP manual they give me with PBP ver 2.47. But you can Find it also at page 168 of PBP3 manual.

Cheers

Al.

[Mike, K8LH]

@Mike K8LH

The PBP manual they give me with PBP ver 2.47. But you can Find it also at page 168 of PBP3 manual.

I wonder if there may be a problem with the PBP3 manual at http://www.pbp3.com/downloads/PBP_Reference_Manual.pdf? It seems to stop downloading at 731 kB (consistently)... Argh!!!

[mackrackit]

Works fine here. I just opened it in my browser.

[Mike, K8LH]

Works fine here. I just opened it in my browser.

Ok, it worked today... I've got it...

[aratti]

Here I post an update of the code posted in #18. This new code has a more efficient ISR so it can read at higher frequency. I don't know the maximum frequency that the system can acheive, so if someone with some spare time will give a try and post the result, could be useful.

As the previuos code, the mainloop doesn't do much, it simply update the display.

Here the code revised:

' PicBasic program to demonstrate how to read an optical encoder
' in quadrature. The code uses a 2 lines LCD in 4-bits mode 
'                 **** MCU USED: PIC 16F628 ***
'
' ------------------ LCD should be connected as follows -------------------
'       LCD     PIC Port
'       ---     --------
'       DB4     PortA.0
'       DB5     PortA.1
'       DB6     PortA.2
'       DB7     PortA.3
'       RS      PortA.4 (add 4.7K pullup resistor to 5 volts)
'       E       PortB.0
'       RW      Ground
'       Vdd     5 volts
'       Vss     Ground
'       Vo      20K potentiometer (or ground)
'       DB0-3   No connected

'-------------------------------------------------------------------------
' Encoder channel A     PortB.6  (use pullups resistor if necessary)
' Encoder channel B     PortB.7  (use pullups resistor if necessary)
' N/U                   PortB.0  (output)
' N/U                   PortB.1  (output)
' N/U                   PortB.2  (output)
' N/U                   PortB.3  (output)
' N/U                   PortB.4  (input - to be grounded)
' N/U                   PortB.5  (input - to be grounded)
'
'-------------------------------------------------------------------------

INCLUDE "DT_INTS-14.bas"    ' Base Interrupt System  (by Darrel Taylor)

DEFINE OSC 20

eeprom 0,[2,0,3,1,1,3,0,2]

Define LCD_DREG PORTA
Define LCD_DBIT 0
Define LCD_RSREG PORTA
define LCD_RSBIT 4
define LCD_EREG PORTB
define LCD_EBIT 0
define LCD_BITS 4
define LCD_LINES 2
define LCD_COMMANDUS 2000
define LCD_DATAUS 50

CMCON = %00000111
TrisA = %00000000
TrisB = %11110000
PortB = 0

Flag                var bit
wsave               VAR BYTE    $70     SYSTEM  ' alternate save location for W 
Q_New               var Byte
Q_Old               var byte
M_Count             var byte [4]
P_Count             var byte [4]
Q_Count             var word

' ---------------------- Set variable value @ startup ----------------------  
     
For Q_Old = 0 to 3
Read Q_Old,M_Count[Q_Old]
Read Q_Old + 4,P_Count[Q_Old]
Next Q_Old
     
  Q_Count = 0   
    Q_New = 0
    Q_Old = 0
     Flag = 0  
      
ASM
INT_LIST  macro    ; IntSource,        Label,  Type,  Resetflag?                
        INT_Handler    RBC_INT,  _Encoder,   ASM,  yes       
    endm
    INT_CREATE                   ; Creates the interrupt processor
ENDASM

@ INT_ENABLE RBC_INT            ; enable external (INT) interrupts

'---------------------------- Initialize LCD ----------------------------

Lcdout $fe, 1                               ' Clear LCD screen
Lcdout "System Ready"                       ' Display message
Pause 500                                   ' Wait .5 second

Goto Main_Loop

Encoder:                                    ' ISR 

Q_New = PortB.7 + PortB.7 + PortB.6         ' get port status
 
If M_Count[Q_Old] = Q_New then              ' if M_Count code satisfied then minus
          Q_Count = Q_Count - 1
             Flag = 1                       ' set flag to true to update display
goto Q_Skip
endif

If P_Count[Q_Old] = Q_New then              ' if M_Count code satisfied then plus
          Q_Count = Q_Count + 1
             Flag = 1                       ' set flag to true to update display
endif

Q_Skip:

Q_Old = Q_New                               ' update Q_Old Byte
 
@ INT_RETURN

Main_Loop:   

if Flag = 1 then
Lcdout $fe, 1                              ' Clear LCD screen
lcdout dec Q_Count                         ' Display encoder position (counts)
Flag = 0                                   ' reset flag to false, display updated
endif

goto Main_Loop

end

Cheers

Al.

[Heckler]

Thanks! Aratti...

I had just finished adapting your earlier example for a 16F690 pic. It took me a while to figure out why my LCD was not working... Dang MCLR pin tripped me up untill I rememberd that it could not act as an output... then I had to move my LCD to PortC... then I had to figure out that my OLD 4 line LCD (bought it about 20 Years ago from AllElectronics) needed more time on the LCD_COMMANDUS.

Anyway it is working GREAT...
I will give your latest code a spin this weekend.

As far as update time to the LCD... it seems to be limited to any Pause or other code that is in the Main Loop. I had been blinking an LED in the main loop using a Pause statement and therefore this limited the LCD update frequency. I think I'll try and impliment another DT-Int using a timer to run the blinking LED in the main loop. This should remove any excessive delay to the LCD update.

PS. I can post Aratti's modified working code for the 16F690 if anybody is interested...

[Mike, K8LH]

.... As far as update time to the LCD... it seems to be limited to any Pause or other code that is in the Main Loop. I had been blinking an LED in the main loop using a Pause statement and therefore this limited the LCD update frequency. I think I'll try and impliment another DT-Int using a timer to run the blinking LED in the main loop. This should remove any excessive delay to the LCD update.

May I offer insight into another way around this problem? I've always been concerned about the overhead of printing to an HD44780 compatible character display. For example, if you tie up the processor for 400 usecs while printing eight (8) characters to the LCD, you might have a problem with another process that needs to run at 100 usec intervals. Instead of updating the display the usual way, with a 40 usec delay between each write, why not refresh the LCD from a 32 character buffer as a background task using interrupts. I did this recently on a TI MSP430 Launchpad project and it worked very well.

Here's the basic idea (C code). Your main program simply writes ASCII data into a 32 character array to update the display. Array elements 0-15 and 16-31 are mapped to LCD lines 1 and 2, respectively. The driver in the ISR only writes one character at a time from the array to the LCD during each interrupt, but I used a 500 usec interrupt interval so the entire display is actually updated around 59 times each second (updates are perceived as instantaneous). Also note that the PutLCD routine (not shown) does not need to include the normal 40 usec LCD inter-character delay.

Food for thought... Regards, Mike

    unsigned char lcd[32] = { "                                " };

    void interrupt()
    {                               // 500 us TMR2 interrupts
      static char bndx = 0x00;      // lcd display buffer index, 0..31
      static char line = 0xC0;      // lcd display DDRAM address

      pir1.TMR2IF = 0;              // clear TMR2 interrupt flag
   /*                                                                   *
    *  refresh one character on the display each interrupt.  entire     *
    *  display refreshed every 17 msecs (58.8 Hz refresh rate).         *
    *                                                                   */
      if(line.7)                    // if "new line"
        PutLCD(line ^= 64,0);       // toggle LCD DDRAM "line" address
      else                          // not "new line" so
        PutLCD(lcd[bndx++],1);      // refresh display, bump index
      bndx &= 31;                   // pseudo mod 31, 0..31 inclusive
      if((bndx & 15) == 0)          // if new line (0 or 16)
        line.7 ^= 1;                // toggle b7 pseudo "new line" flag
    }

[Ioannis]

For some peculiar reason that I cannot understand, Al's code is counting +/- 4 steps instead of one for each click.

Anyone can speculate why?

With a logic analyzer I have confirmed that the encoder is working fine. Here is a snapshot for 4 clicks of the encoder.



Ioannis

[HenrikOlsson]

Hi Ioannis,
I haven't looked at the particular code in question but generally, you decode all 4 edges, hence the term quadrature. Look at the capture for one click, first Ch.0 goes low (1) then Ch.1 goes low (2), then Ch.0 goes high (3) and finally Ch.1 goes high (4). So, 4 counts per click.

/Henrik.

[Ioannis]

Hmm, thanks Henrik, it looks logic now... well...

Ioannis

[Demon]

I need a rotary encoder for manual input in flight simulator; changing radio frequency, autopilot altitude, etc. I like the "slower" detection in post #1 for this particular application or else I'd issue 4 keyboard commands in a single detent. 100 feet would change to 500 feet with a single click with no way to set to the in-between values.

But Podgy brings up a very important point; all rotary encoder datasheets I've seen mention debounce. I know most PIC inputs have Schmitt triggers, but just how effective are they in these cases? I can't test until my batch arrives.

Robert

[Ioannis]

a couple of 100nF were needed for mine. After placing the caps to ground from each encoder output pin, false readings were a past.

Ioannis

[fratello]

Need help with one enconder ... a little different.
How can I read the "up/+" and "down/-" action of this particular encoder ?
Any help will be appreciated ! Thanks in advance !

[fratello]

It's ok something like this ?!

TrisA = %00000000
TrisB = %11110000
PortB = 0

Flag                var bit
Q_New               var Byte
Q_Old               var byte
M_Count             var byte [4]
P_Count             var byte [4]
Q_Count             var word

' ---------------------- Set variable value @ startup ----------------------  
     
For Q_Old = 0 to 3
Read Q_Old,M_Count[Q_Old]
Read Q_Old + 4,P_Count[Q_Old]
Next Q_Old
     
  Q_Count = 0   
    Q_New = 0
    Q_Old = 0
     Flag = 0  
                        

Goto Main_Loop

Encoder:                                    '
Q_New = PortB.7 + PortB.6 + PortB.5         ' get port status
 
If M_Count[Q_Old] = Q_New then              ' if M_Count code satisfied then minus
          Q_Count = Q_Count - 1
             Flag = 0                       ' set flag for DOWN
goto Q_Skip
endif

If P_Count[Q_Old] = Q_New then              ' if M_Count code satisfied then plus
          Q_Count = Q_Count + 1
             Flag = 1                       ' set flag for UP
endif


Q_Skip:
Q_Old = Q_New                               ' update Q_Old Byte
 

Main_Loop:   
if Flag = 1 then do command1                             
if Flag = 0 then do command2                                  
goto Main_Loop

[fratello]

So far...no good ...
Complete "hardware" it's like in picture . I intend to use an remote with some "rotary encoder" ...
The remote controller has six wires . They are connected to three rows and three columns. This allows maximum of 3*3=9 functions. Roller takes three functions because it must be possible to know which way it is rotated (how doing this in PBP ?!?). Rest of the functions are assigned to six buttons.
I use great pice of code (keypad matrix routine) of Mr. Mister-e and the "regular" buttons works verry fine...but I want to use the function of roller too.
I can't figure out how doing this, so any "clue" will be appreciated !

[HenrikOlsson]

Hi,
Without analyzing your code in detail one possible problem might be this line

Q_New = PortB.7 + PortB.6 + PortB.5         ' get port status

In this case you'll get Q_New = 1 no matter WHICH of the three pins are high. I'm not sure but I guess that's not what you want.

You could try something like Q_New = PortB & %11100000 >> 5 instead.

Here's another approach (untested) which is smaller in terms of program space and RAM but like I said it's untested so it might not even work.

oldState VAR BYTE
newState VAR BYTE
Q_Count VAR WORD
DIR VAR BIT

UP CON 1
DN CON 0

newState = (PortB & %11100000)      ' Isolate top three bits, newState will be 32, 64 or 128 

If newState <> 0 THEN
If newState <> oldState THEN        ' Changed from last time?

  Select Case oldState
    Case 32
    If NewState = 128 THEN          ' Was 1 now 4 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                          ' Was 1 now 2 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  
    Case 64
    If NewState = 32 THEN        ' Was 2 now 1 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                           ' Was 2 now 4 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  
    Case 128
    If NewState = 64 THEN        ' Was 4 now 2 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                       ' Was 4 now 1 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  END SELECT

  oldState = NewState

ENDIF
ENDIF

[fratello]

It a real pleasure to see how generous some people can be ... Thank You, AGAIN, Mr. Henrik !
...I think I missing something ... If UP do something, If Down do something else...dont ?!
But nothing happens.

'****************************************************************
 @ DEVICE pic16F628A, XT_OSC, WDT_OFF, PWRT_ON, BOD_OFF, MCLR_ON, LVP_OFF

   Define   OSC 4           ' 4MHz 
   CMCON = 7                ' Disable on-chip comparator, PORTA in digital mode

include "alldigital.pbp"

TrisA = 000000
PortB = 010000
TrisB = 000000

oldState VAR BYTE
newState VAR BYTE
Q_Count VAR WORD
DIR VAR BIT

UP CON 1
DN CON 0


Main_Loop:  
newState = (PortB & 100000)    
goto encoder
if dir = up then portb.0 = 1                           
if dir = dn then portb.1 = 1 
goto Main_Loop 
goto encoder
if dir = up then 
portb.4 = 1
portb.0 = 1
endif                           
if dir = dn then 
portb.4 = 0
portb.1 = 1
endif
goto Main_Loop


encoder:

If newState <> 0 THEN
If newState <> oldState THEN        ' Changed from last time?

  Select Case oldState
    Case 32
    If NewState = 128 THEN          ' Was 1 now 4 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                          ' Was 1 now 2 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  
    Case 64
    If NewState = 32 THEN        ' Was 2 now 1 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                           ' Was 2 now 4 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  
    Case 128
    If NewState = 64 THEN        ' Was 4 now 2 = Up
      Q_Count = Q_Count + 1
      DIR = UP
    ELSE                       ' Was 4 now 1 = Down
      Q_Count = Q_Count - 1
      DIR = DN
    ENDIF

  END SELECT

  oldState = NewState 

ENDIF
ENDIF

Or I wired the roller wrong ?
Here ( http://www.angelfire.com/nd/maza/kenwood.html ) it's a working variant, but in other "way" , using Atmega ...

[mackrackit]

http://www.picbasic.co.uk/forum/show...3089#post33089