Quad Encoder Problem

[Ioannis]

It is too much to have very often (on every click of the rotary encoder) to write the value in EEPROM.

Do it when there is really a need for this, e.g. when the value is different from old value AND a certain time has passed. This time should be reset while the encoder is rotating.

Ioannis

[RossWaddell]

It is too much to have very often (on every click of the rotary encoder) to write the value in EEPROM.

Do it when there is really a need for this, e.g. when the value is different from old value AND a certain time has passed. This time should be reset while the encoder is rotating.

Ioannis

That makes sense, Ioannis. I didn't want to lose a user setting if power was interrupted before the save but maybe I could set up a timer (using DT's interrupt library) to check if the value is changed every 30 seconds or so.

[HenrikOlsson]

Hi,

What's weird is the 'MotorRPM' as displayed on the LCD jumps by 3-4 (i.e. current setting is '120' and then one click of the encoder makes it '124').

Not weird, as I wrote earlier - turning the encoder from one click/detent to the next results in one quadrature cycle which is four "edges", ie four interrupts so, four counts:



That's why you can't have any delay in the ISR because turning the encoder one "click" results in four interrupts, if you have a delay (Pause or other) in there it misses one or more of the four edges in the cycle and gets confused.

You could setup a timer for the EEPROM save, or you could just set a variable to some value in the ISR, the Main routine then decrements this value and when it hits zero you save the value to EEPROM. That will allow the user to turn the knob and the value be saved some time after the change is complete, psuedo code

TimeToSave VAR WORD
ValueDirty VAR BIT

Main:
   'Code...
   'Code...

   If ValueDirty THEN
     TimeToSave = TimeToSave - 1
     If TimeToSave = 0            ' Time to save ?
       Write.....
       ValueDirty = 0               ' Clear the flag
     ENDIF
   ENDIF

   'Code
   'Code
Goto Main

ISR:
  TimeToSave = 5000
  ValueDirty = 1
  'More code....
@ INT_RETURN

Here the interrupt routine sets a flag indicating that the value has changed, it also sets a "counter" variable which the main routined counts down. If the Main routine executed 5000 times without the value being changed it saves the value to EEPROM. Obviously this relies on a somewhat constant execution time thru the Main routine but you get the idea.

/Henrik.

EDIT: Cross posting.... As for the other "weird" thing. It seems that DT-Ints does NOT handle clearing hte interrupt request flag for the IOC interrupt on these devices so you SHOULD to do that manually before exiting the interrupt (normally NOT needed when the ClearFlag switch is set to Yes). If the interrupt request flag is NOT cleard the interrupt refires over and over and over again which is why the button doesn't seem to work - that code never runs because the CPU spends all the time servicing the interrupt. At least that's what I think is happening, I know it didn't work here if I didn't clear the flags manually.

[RossWaddell]

Hi,

Not weird, as I wrote earlier - turning the encoder from one click/detent to the next results in one quadrature cycle which is four "edges", ie four interrupts so, four counts:

Attachment 6894

I coulda sworn I had it incrementing by 1 in earlier versions (back when I was using HPWM). Nonetheless, I believe I need to detect the 4 edges in order to determine the direction of turn, so maybe I'll add a counter (1-4) in the ISR and only increment MotorRPM when it hits 4 (and then reset).

You could setup a timer for the EEPROM save, or you could just set a variable to some value in the ISR, the Main routine then decrements this value and when it hits zero you save the value to EEPROM. That will allow the user to turn the knob and the value be saved some time after the change is complete, psuedo code

TimeToSave VAR WORD
ValueDirty VAR BIT

Main:
   'Code...
   'Code...

   If ValueDirty THEN
     TimeToSave = TimeToSave - 1
     If TimeToSave = 0            ' Time to save ?
       Write.....
       ValueDirty = 0               ' Clear the flag
     ENDIF
   ENDIF

   'Code
   'Code
Goto Main

ISR:
  TimeToSave = 5000
  ValueDirty = 1
  'More code....
@ INT_RETURN

I'll try this out. At first glance, though, the ISR is always setting TimeToSave to 5000 so I think it needs a check like:

If ValueDirty = 0 Then
  TimeToSave = 5000
EndIf

EDIT: Cross posting.... As for the other "weird" thing. It seems that DT-Ints does NOT handle clearing hte interrupt request flag for the IOC interrupt on these devices so you SHOULD to do that manually before exiting the interrupt (normally NOT needed when the ClearFlag switch is set to Yes). If the interrupt request flag is NOT cleard the interrupt refires over and over and over again which is why the button doesn't seem to work - that code never runs because the CPU spends all the time servicing the interrupt. At least that's what I think is happening, I know it didn't work here if I didn't clear the flags manually.

I'll have to add a comment to my IOC ISR's that I do need to clear the flags.

Thanks again, Henrik!

[RossWaddell]

This works. Probably a bit inefficient having the TMR1 interrupt firing @ 8Hz, but if only writes to EEPROM if the value has changed:

 
' ***************************************************************
' Pin Connections
' ***************************************************************

' RA0/pin 13                       -> B pin of rotary encoder
' RA1/pin 12                       -> A pin of rotary encoder
' RA2/CCP3/pin 11                  -> Stbd motor PWM output (motor 1)
' RA3/MCLR/pin 4                   -> Button switch pin of rotary encoder
' RC0/pin 10                       -> Stbd motor direction signal (motor 1)
' RC1/CCP4/pin 9                   -> Port motor PWM output (motor 2)
' RC2/pin 8                        -> Port motor direction signal (motor 2)
' RC4/Tx/pin 6                     -> Serial LCD output
' RC5/Rx/pin 5                     -> Serial input
      
DEFINE OSC 16               ; Set oscillator 16Mhz
DEFINE HSER_TXSTA   20h     ; Set transmit status and control register
DEFINE HSER_BAUD    2400    ; Set baud rate

#CONFIG
   __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
   __config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG

' ***************************************************************
' Initialization
' ***************************************************************

OSCCON   = %01111000        ' 16MHz internal osc

pause 100                   ' As advised by Darrel Taylor for EEPROM issue

APFCON0.2 = 0               ; Tx on RC4 for LCD display
APFCON0.7 = 0               ; Rx on RC5

BAUDCON.4 = 1               ; Transmit inverted data to the Tx pin

ANSELA    = 0               ; Digital only for all PortA pins
ANSELC    = 0               ; Diginal only for all PortC pins

TRISA     = %00001011       ' Make PORTA pins 0-1 input for rotary encoder,
                            ' pin 3 for rotary button
TRISC     = 0               ' Make all PORTC pins output

' The INTEDG bit of the OPTION_REG register determines on which edge the 
' interrupt will occur. When the INTEDG bit is set, the rising edge will 
' cause the interrupt. When the INTEDG bit is clear, the falling edge will 
' cause the interrupt. 
OPTION_REG.6 = 1             ' 1=Rising edge (default) or button "PRESS";
                             ' 0=Falling edge or button "RELEASE"

Old_Bits       VAR BYTE
New_Bits       VAR BYTE
RotEncDir      VAR BIT       ' 1=CW, 0=CCW
                             ' Rot Enc pin A connected to PortA.1;
                             ' Rot Enc pin B connected to PortA.0
Old_RPM        VAR BYTE
i              VAR BYTE

ButtonPress    VAR PORTA.3   ' Alias PORTA.3 as "ButtonPress"

TimeCnt     VAR Word      

ISRCounter  VAR BYTE
ValueDirty  VAR BIT

' ***************************************************************
' Includes
' ***************************************************************

INCLUDE "DT_INTS-14.bas"    ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"    ' Include if using PBP interrupts
                            ' --> copy both files to PBP main folder 
                            ' (i.e. c:\pbp3)
                                                                  
' ***************************************************************
' ASM Interrupt Definitions
' ***************************************************************
                                                                  
ASM
INT_LIST  macro    ; IntSource,         Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,    ReloadTMR1,   ASM,  no       ; MUST be first
        INT_Handler   TMR1_INT,    _T1handler,   PBP,  yes
        INT_Handler    IOC_INT, _RotEncAdjust,   PBP,  yes
    endm
    INT_CREATE     ; Creates the interrupt processor
ENDASM

;--- Change these to match the desired interrupt frequency -------------------
;--- See http://DarrelTaylor.com/DT_INTS-14/TimerTemplate.html for more Info.
@Freq       = 8                   ; Frequency of Interrupts in Hz
@Prescaler  = 8                   ; Timers Prescaler setting
T1CON = $30                       ; $30 = Prescaler 1:8, TMR1 OFF
; $00=1:1, $10=1:2, $20=1:4, $30=1:8 --  Must match @Prescaler value

' ***************************************************************
' Set default values
' ***************************************************************

Old_RPM = MotorRPM
Old_Bits = PORTA & (%00000011)
ISRCounter = 0


' 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
IOCAP.0  = 1                ' Enable positive (rising edge) change
IOCAP.1  = 1                ' Enable positive (rising edge) change
IOCAN.0  = 1                ' Enable negative (falling edge) change
IOCAN.1  = 1                ' Enable negative (falling edge) change
IOCAF.0  = 0                ' Clear interupt-on-change flag
IOCAF.1  = 0                ' Clear interupt-on-change flag

@ INT_ENABLE   IOC_INT      ; Interrupt-on-Change interrupt
@ INT_ENABLE  TMR1_INT      ; enable Timer 1 interrupts
GOSUB StartTimer            ; Start Timer 1 ('MotorRPM' will be saved on every
                            ; interrupt if dirty

Main:
    ' Check if motor RPM has changed
    IF MotorRPM <> Old_RPM Then
        Old_RPM = MotorRPM
        GOSUB ChngMotorHPWM
    EndIF   
   
    TimeCnt = 0
	While ButtonPress = 0
	    TimeCnt = TimeCnt + 1
	    Pause 10
	    If TimeCnt > 500 Then BtnAction
	Wend
 
    BtnAction:
        If TimeCnt > 0 and TimeCnt < 200 Then
            PortEngDir = PortEngDir + 1
            If PortEngDir > 1 Then PortEngDir = 0
    
            WRITE EE_PortEngDir, PortEngDir
            #IFDEF USE_LCD_FOR_DEBUG
                HSEROUT [LCD_INST, LCD_CLR]
                pause 5
                HSEROUT ["PortEngDir=", DEC PortEngDir, "  ", 13, 10] ' Send text followed by carriage return and linefeed
            #ENDIF

            GOSUB ReversePortEng
        ElseIf TimeCnt >= 200 Then
            WRITE EE_MotorRPM, MotorRPM_Default  ; restore Default value
        
            MotorRPM = MotorRPM_Default
        EndIf
 
    GOTO Main


' ***************************************************************
' [IOC - interrupt handler]
' ***************************************************************
RotEncAdjust:
    New_Bits = PORTA & (%00000011)
;    IF (New_Bits & %00000011) = (Old_Bits & %00000011) Then DoneRotEnc
    IF New_Bits = Old_Bits Then DoneRotEnc

    ' Increment ISR counter (since quad encoder throws 4 interrupts
    ' for every single detent). Only want to update MotorRPM if this counter
    ' reaches 4 (i.e. a single detent)
    ISRCounter = ISRCounter + 1
    IF ISRCounter < 4 THEN DoneRotEnc

    RotEncDir = New_Bits.1 ^ Old_Bits.0
    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

;    GOSUB StartTimer            ; Start the TMR1 Timer to save MotorRPM
    ValueDirty = 1

    ISRCounter = 0
;    WRITE EE_MotorRPM, MotorRPM
;    pause 100

DoneRotEnc:
    Old_Bits = New_Bits

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

@ INT_RETURN

;____This routine is Called on each TMR1 Interrupt____________________________
T1handler:
    IF ValueDirty = 1 THEN
       WRITE EE_MotorRPM, MotorRPM  
;    GOSUB StopTimer             ; Stop the Timer
   
       ValueDirty = 0
    EndIf

@ INT_RETURN

;---[TMR1 reload - interrupt handler]-----------------------------------------
ASM                               ; Calculate Timer Reload Constant
ReloadInst  = 8                   ; # of Intructions used to reload timer
  if ((Prescaler == 1)||(Prescaler == 2)||(Prescaler == 4)||(Prescaler == 8))
MaxCount    = 65536 + (ReloadInst / Prescaler)
TimerReload = MaxCount - (OSC*1000000/4/Prescaler/Freq)
    if ((TimerReload < 0) || (TimerReload > (65535-ReloadInst)))
        error Invalid Timer Values - check "OSC", "Freq" and "Prescaler"
    endif
  else
      error Invalid Prescaler
  endif
ENDASM

@Timer1 = TMR1L                   ; map timer registers to a word variable
Timer1       VAR WORD EXT
TimerReload  CON EXT              ; Get the External Constant
TMR1ON       VAR T1CON.0          ; Alias the Timers ON/OFF bit

;---Reload Timer1------
ASM
ReloadTMR1
    MOVE?CT  0, T1CON, TMR1ON     ;  1     stop timer
    MOVLW    LOW(TimerReload)     ;  1     Add TimerReload to the 
    ADDWF    TMR1L,F              ;  1     value in Timer1
    BTFSC    STATUS,C             ;  1/2
    INCF     TMR1H,F              ;  1
    MOVLW    HIGH(TimerReload)    ;  1
    ADDWF    TMR1H,F              ;  1
    MOVE?CT  1, T1CON, TMR1ON     ;  1     start timer
  INT_RETURN
ENDASM

;---Start/Stop controls -----
StartTimer:
    Timer1  = TimerReload         ; Load Timer
    TMR1ON = 1                    ; start timer
RETURN

StopTimer:
    TMR1ON = 0                    ; stop timer
RETURN

(When I turn off the PIC and turn it on again, it sometimes seems to speed up the motor to (MotorRPM - 1), i.e. 1 less than what was displayed on the LCD before turning off power.

[HenrikOlsson]

I'll try this out. At first glance, though, the ISR is always setting TimeToSave to 5000 so I think it needs a check like:

Well, yes, that was the whole idea. As long as the user keeps turning the knob (generating interrupts) the counter will get reset to 5000 (or whatever). But as soon as the user has NOT changed the RPM for the duration of 5000 iterations thru the Main loop the value is saved. When the knob isn't being turned no interrupts are being generated so the Main routine eventually gets the counter down to 0 and saves the value.

/Henrik.

[RossWaddell]

Oop. Yeah, of course that makes sense. Thanks.