Quad encoder problems


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  1. #1
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    Thanks for the info sayzer! Not sure I explained what I am doing very well. I did some more searching and found out I have 2 bit encoders, not quad. I am using them with a weight attached to one side so they are always parallel to the ground. What I want to do is use them as attitude sensors for pitch and roll in a telemetry system I am building.

    They have 36 slots each and return a code of 00 01 11 10 in one direction and 10 11 01 00 in the other. I have it working but it seams to bounce or glitch. I think the 16f628 at 20mhz isnt fast enough to keep up.

    Here is what I have so far.
    Val should return a value from 2 to 145. Its for 36 slots * 4 states per slot.


    INPUT PORTB.4
    INPUT PORTB.5
    LCDOUT $FE, 1
    VAL VAR WORD
    VAL = 2

    MAIN:
    LCDOUT $FE, 1
    LCDOUT $FE, $80, #PORTB.4, #PORTB.5
    LCDOUT $FE, $C0, #VAL
    IF PORTB.4 = 0 AND PORTB.5 = 0 THEN Q00
    IF PORTB.4 = 0 AND PORTB.5 = 1 THEN Q01
    IF PORTB.4 = 1 AND PORTB.5 = 1 THEN Q11
    IF PORTB.4 = 1 AND PORTB.5 = 0 THEN Q10
    GOTO MAIN
    Q00:
    IF PORTB.4 = 0 AND PORTB.5 = 1 THEN VALADD
    IF PORTB.4 = 1 AND PORTB.5 = 0 THEN VALMINUS
    GOTO Q00


    Q01:
    IF PORTB.4 = 1 AND PORTB.5 = 1 THEN VALADD
    IF PORTB.4 = 0 AND PORTB.5 = 0 THEN VALMINUS
    GOTO Q01


    Q11:
    IF PORTB.4 = 1 AND PORTB.5 = 0 THEN VALADD
    IF PORTB.4 = 0 AND PORTB.5 = 1 THEN VALMINUS
    GOTO Q11


    Q10:
    IF PORTB.4 = 0 AND PORTB.5 = 0 THEN VALADD
    IF PORTB.4 = 1 AND PORTB.5 = 1 THEN VALMINUS
    GOTO Q10

    VALADD:
    VAL = VAL + 1
    IF VAL > 145 THEN VAL = 2
    GOTO MAIN

    VALMINUS:
    VAL = VAL - 4
    IF VAL < 2 THEN VAL = 145
    GOTO MAIN

  2. #2
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    Default Use Interrupts!!

    Smitty,

    Go to Darrel Taylor's Instant Interrupt Site and download DT_INTS-14.bas and ReEnterPBP.bas

    In the DT_INTS-14.bas file, comment out the Highlighted line below, as shown.

    Code:
    '****************************************************************
    '*  Name    : DT_INTS-14.bas                                    *
    '*  Author  : Darrel Taylor                                     *
    '*  Version : 0.93 BETA                                         *
    '*  Date    : JAN 29, 2006                                      *
    '****************************************************************
    '* Rev 0.93  Fixed CMIF and EEIF problem with older PIC's       *
    '*           that have the Flags in PIR1 instead of PIR2        *
    '* Rev 0.92  solves a "Missed Interrupt" and                    *
    '*           banking switching problem                          *
    '****************************************************************
    DEFINE  INTHAND  INT_ENTRY
    
    wsave       var byte    $20     SYSTEM      ' location for W if in bank0
    ;wsave       var byte    $70     SYSTEM     ' alternate save location for W 
                                                ' if using $70, comment out wsave1-3
    
    ' --- IF any of these three lines cause an error ?? ---------------------------- 
    '       Comment them out to fix the problem ----
    ' -- It depends on which Chip you are using, as to which variables are needed --
    wsave1      var byte    $A0     SYSTEM      ' location for W if in bank1
    wsave2      var byte    $120    SYSTEM      ' location for W if in bank2
    'wsave3      var byte    $1A0    SYSTEM      ' location for W if in bank3
    ' ------------------------------------------------------------------------------
    Below is a bit of untested code (I don't have a 16F628 nor 2 Available Rotary Encoders) I threw together to get you started. It did compile without errors (if you made the change to DT_INTS-14.bas above), just can't actually try it in a PIC (let alone your setup). This code should allow you do keep track of both the rotary encoders regardless of what else your program is doing.


    Code:
    Old_Bits       VAR BYTE
    New_Bits       VAR BYTE
    RotEnc1_val    VAR BYTE  'Connected to PORTB<4:5>
    RotEnc2_val    VAR BYTE  'Connected to PORTB<6:7>
    TRISB = %11110000
    RotEncDir      VAR BIT
    '************************
    ' SETUP YOUR LCD HERE!!!
    '************************
    
    
    INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
    INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts
    
    ASM
    INT_LIST  macro    ; IntSource,         Label,  Type, ResetFlag?
            INT_Handler    RBC_INT,  _Rot_Encoder,   PBP,  yes
        endm
        INT_CREATE               ; Creates the interrupt processor
    ENDASM
    
    @    INT_ENABLE   RBC_INT     ;RB Port Change Interrupt
    
    Old_Bits = PORTB & (%11110000)
    Main:
         LCDOUT $FE, 2,"ROT1:", DEC2 RotEnc1_val,"ROT2:", DEC2 RotEnc2_val
         pause 10     
    GOTO Main
    
    '---[RBC - interrupt handler]---------------------------------------------------
    Rot_Encoder:
         New_Bits = PORTB & (%11110000)
         IF (New_Bits & %00110000) = (Old_Bits & %00110000) then No_Change_Rot1
         RotEncDir = New_Bits.5 ^ Old_Bits.4
         if RotEncDir = 1 then
              RotEnc1_val = RotEnc1_val + 1
              if RotEnc1_val = 36 then RotEnc1_val = 0
         ELSE
              RotEnc1_val = RotEnc1_val - 1
              if RotEnc1_val = 255 then RotEnc1_val = 35
         ENDIF
    No_Change_Rot1:
         IF (New_Bits & %11000000) = (Old_Bits & %11000000) then DoneRotEnc
         RotEncDir = New_Bits.7 ^ Old_Bits.6
         if RotEncDir = 1 then
              RotEnc2_val = RotEnc2_val + 1
              if RotEnc2_val = 36 then RotEnc2_val = 0
         ELSE
              RotEnc2_val = RotEnc2_val - 1
              if RotEnc2_val = 255 then RotEnc2_val = 35
         ENDIF
    DoneRotEnc:
         Old_Bits = New_Bits
    @ INT_RETURN
    A couple of items to mention. It assumes the you have connected your rotary encoders with the "A" Pins on PORTB.4 and 6, and "B" Pins on PORTB.5 and 7. Also, you have to have pull-ups on all 4 lines. If it "sort-of" works, try switching the lines on the encoders to the opposite pins.

    I assumed you will configure you lcd on you own as needed.

    Also make sure the files downloaded from Darrel Taylor are in the some directory as the main program file.

    HTH,
    Steve B

  3. #3
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    WOW! Thanks Steve!

    Makes my code look like a 5 yo did it. LOL

    Ok, did what you said and commented out the line you highlighted.
    Then put both "DT_INTS-14.bas" and "ReEnterPBP.bas" into the same folder as your code.

    "DT_INTS-14.bas" had to be renamed because it downloaded as "DT_INTS-14[1].bas.txt"

    "ReEnterPBP.bas" had to be renamed because it downloaded as "ReEnterPBP.bas[1].bas.txt"

    When I try to compile it in PBP I get some errors. I am not used to asm includes so I might be doing something wrong.

    It is unable to load both include files and 3 other errors.

    See attached screencap

    Thanks,
    Smitty
    Attached Images Attached Images  

  4. #4
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    Smitty,
    Try this on your cmd line:

    pbpw -p16f628 -ampasmwin yourfilename

    The trouble is actually two fold.
    1) PBP is DOS based, and does not like long file names. PBPW is ok with them.
    2) You need to use the MPASM assembler. So make sure it is installed before you run the above line! It is needed for the Macros, as well as if you make the switch to the 18F series.

    Out of curiosity, why not use MicroCode Studio?

    Good Night,
    Steve B

    EDIT: Use the name for your file on the above cmd line
    Last edited by SteveB; - 10th September 2006 at 14:18.

  5. #5
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    Quote Originally Posted by SteveB
    Smitty,
    .....
    Out of curiosity, why not use MicroCode Studio?
    .....
    Hi Smitty,

    As Steve B also asks about it here, is there a particular reason why you are not using MicroCode Studio?

    Also, for the encoder , don't you think that you can do what you need with one direction?

    If you think you can, then I can give you some piece of code for TMR1 and TMR0 so that you can set it up for reading the encoder, and suggest some ways of having the missing counts minimized.

    In your case, as much as I understood it, the degrees needed are wide enough to cover the missing counts.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

  6. #6
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    Default 7 hours and still trying

    I just tried microcode studio and get the same errors. Cant find 16F628.inc

    This file is in the pbp directory, I do not understand.

    sayzer, Thanks for the offer but I do need both directions to be able to tell if it is a right or left roll ,an up or down pitch and how far for both.

    Microcode studio is pretty sweet I must say. Thanks for recommending it.

    Smitty

  7. #7
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    You did restart your computer, right? Well, if we don't have any success going that route, there are alternatives.

    Look at the code in the Interrupt Handler. Put this in your main loop, so it repeatedly checks PORTB for changes. Like This:

    Code:
    '************************
    '  DEFINE your OSC 
    '  and any other
    '  configuation items
    '************************
    
    
    Old_Bits       VAR BYTE
    New_Bits       VAR BYTE
    RotEnc1_val    VAR BYTE  'Connected to PORTB<4:5>
    RotEnc2_val    VAR BYTE  'Connected to PORTB<6:7>
    TRISB = %11110000
    RotEncDir      VAR BIT
    
    '************************
    ' SETUP YOUR LCD HERE!!!
    '************************
    
    Old_Bits = PORTB & (%11110000)
    
    Main:
         New_Bits = PORTB & (%11110000)
         IF (New_Bits & %00110000) = (Old_Bits & %00110000) then No_Change_Rot1
         RotEncDir = New_Bits.5 ^ Old_Bits.4
         if RotEncDir = 1 then
              RotEnc1_val = RotEnc1_val + 1
              if RotEnc1_val = 36 then RotEnc1_val = 0
         ELSE
              RotEnc1_val = RotEnc1_val - 1
              if RotEnc1_val = 255 then RotEnc1_val = 35
         ENDIF
    No_Change_Rot1:
         IF (New_Bits & %11000000) = (Old_Bits & %11000000) then DoneRotEnc
         RotEncDir = New_Bits.7 ^ Old_Bits.6
         if RotEncDir = 1 then
              RotEnc2_val = RotEnc2_val + 1
              if RotEnc2_val = 36 then RotEnc2_val = 0
         ELSE
              RotEnc2_val = RotEnc2_val - 1
              if RotEnc2_val = 255 then RotEnc2_val = 35
         ENDIF
    DoneRotEnc:
         Old_Bits = New_Bits
         
         LCDOUT $FE, 2,"ROT1:", DEC2 RotEnc1_val,"ROT2:", DEC2 RotEnc2_val
    GOTO Main



    Let's walk before we run and get this working.

    Steve

  8. #8
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    Steve,
    Yup, restarted pc many times. LOL. I would really like to know what the problem is. I guess I will have to look into it further.

    You said "Look at the code in the Interrupt Handler. Put this in your main loop"

    Did you mean to compile just the code you listed or to add it to one of the others? If you meant by itself then it compiled just fine.

    I tried it out and had some strange readings. It starts with Rot1:00 and Rot2:35. When I rotate the encoders nothing happens.

    To test and see if it was the encoder or the program, I unpluged the a & b chanels from encoder 1 and alternately touched them to ground and the numbers changed. This makes me think something is wrong in the encoder circuit. I played arround with different values on the resistors to no avail. The encoders output a positive voltage between ~1.85 and 5 and I have 4.7K resistors pulled to ground on each channel.

    I did notice if I was under a bright light and held the encoders at just the right angle the numbers changed but they were jumping arround and not going 1.2.3.4~.

    Man I didnt think encoders were so tough.

    Smitty

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