New approach to Rotary Encoder

[HenrikOlsson]

Great, finally... Now try removing the PAUSE 15 and see if that improves it further.

[fratello]

Thanks to Mr.Henrik Olsson this code work PERFECT !!! I'm sure I would not have done it without his help !

Main:
    PortA.1 = 0
    newState = PortA & 011100        
    PortA.1 = 1

    If newState <> 28 THEN
        If newState <> oldState THEN
              
            Select Case oldState
                Case 12
                If NewState = 20 THEN dir=up       
                If NewState = 24 THEn dir=dn
                
                Case 20
                If NewState = 24 THEN dir=up               
                If NewState = 12 THEN dir=dn
               
                Case 24
                If NewState = 12 THEN dir=up                       
                If NewState = 20 THEN dir=dn
            END SELECT

            GOSUB UpOrDn 

    PortA.1 = 0
    OldState = PortA & 011100         
    PortA.1 = 1
               
       endif          
    ENDIF
Goto Main

[kzeoprf]

Hi to all. I want to use a rotary encoder with a 18f252, and i have a lot of troubles. I want to use interupts, so my only solution PORTB or I can use Portc also?

I made a pcb and I made the connections to PORTC, and I also use a debounce circuit, which I think causes problems. Anyone has a snipset code cause I do not have any expieriance with encoders?
5v
__|__
| |
/ /
\ \
/10k / 10K
\ \
| A | B ENC
- -
| |-------------------------------
\ |
/10K \
\ /10K
/ \
|--------------------- |--------------------
PORTC.2 | PORTC.3 |
---- ----- 100nF
---- -----
| |
--------- -----------
----- -----
- -

[HenrikOlsson]

Hello,
On the 18F252 there's no interrupt capabillity on PortC.

Your schematic really doesn't show up that good here but it LOOKS like you have a 10k from 5V to the "top" of each of the switches in the encoders, then the other side of each switch thru another 10k to the input with a 100nF cap to GND, is that correct?

If the above is not correct please post a proper schematic for us to see.
If the above IS correct then it's not a very good hardware design IMHO. When the switch in the ecoder is closed you have 2*10k in series to the input, decoupled by a 100nF cap, this may be fine. But when the switch is open there's no path for the capacitor to discharge except thru the fairly high input impedance of the pin. In effect the pin floats which is not a good thing for inputs.

/Henrik.

[Demon]

I finally got around to trying my rotary encoders out on an 18F24K22 using DT interrupts.

I kept things simple; checking for only 1 movement per click (detent). This encoder also has a momentary ON switch.

'***************************************************************************
'*  Name    : 18F24K22 encoder.pbp                                         *
'*  Author  : Demon                                                 *
'*  Date    : Sep 5 2012                                                   *
'*  Version : 1.0                                                          *
'*  Hardware : PIC 18F24K22, internal oscillator, 8 MHz                    *
'*           : ICSP                                                        *
'*           : MeLabs U2 Programmer v4.32                                  *
'*  Software : PIC Basic Pro v2.60C                                        *
'*           : MicroCode Studio Plus v2.2.1.1                              *
'*           : MPASM v5.46                                                 *
'*  CONFIG   : - if you use these, you must comment the ones in the        *
'                .INC file in PBP folder                                   *
'              - available options at the bottom of P*.INC file in         *
'                MPLAB TOOLS/MPASM SUITE folder                            *
'***************************************************************************
asm
 __CONFIG    _CONFIG1H, _FOSC_INTIO67_1H & _PLLCFG_OFF_1H & _PRICLKEN_ON_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
 __CONFIG    _CONFIG2L, _PWRTEN_ON_2L & _BOREN_SBORDIS_2L & _BORV_285_2L
 __CONFIG    _CONFIG2H, _WDTEN_OFF_2H
 __CONFIG    _CONFIG3H, _PBADEN_ON_3H & _HFOFST_OFF_3H & _MCLRE_EXTMCLR_3H
 __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
endasm

;--- Oscillator speed ------------------------------------------------------

DEFINE OSC 8
CLEAR

;--- Setup Interrupts ------------------------------------------------------
INCLUDE "DT_INTS-18.bas"        ; Base Interrupt System
INCLUDE "ReEnterPBP-18.bas"     ; PBP Re-entry for external interrupt

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler    INT_INT,  _ExternalInterrupt0,   PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM

@   INT_ENABLE   INT_INT     ; enable external (INT) interrupts

;--- Setup Registers -------------------------------------------------------

OSCCON = %01100110              ' OSCILLATOR CONTROL REGISTER
OSCTUNE = %00000000             ' OSCILLATOR TUNING REGISTER

PMD0 = %11111111                ' PERIPHERAL MODULE DISABLE REGISTER 0
PMD1 = %11111111                ' PERIPHERAL MODULE DISABLE REGISTER 1
PMD2 = %00001111                ' PERIPHERAL MODULE DISABLE REGISTER 2

INTCON2=%10000100               ' INTERRUPT CONTROL 2 REGISTER

ANSELA = 0                      ' Digital I/O
ANSELB = 0                      ' Digital I/O
ANSELC = 0                      ' Digital I/O

;--- Setup Port directions -------------------------------------------------

TRISA = %00000000               ' Set port A pins to output
TRISB = %00000001               ' Set port B pin 0 to input, others output
TRISC = %00000110               ' Set port C pins 1,2 to input, others output

;--- Pins ------------------------------------------------------------------

WiperA      VAR PortB.0         ' Interrupt 0
WiperB      VAR PortC.2

Switch      VAR PortC.1

LedPower    VAR PortB.5

;--- Variables -------------------------------------------------------------

LEDS        VAR BYTE            ' 8 Leds connected on Port A

;--- Program Start ---------------------------------------------------------

start:

Pause 200                       ' Let PIC stabilize

Ledpower = 0

Leds = %00000001
PortA = leds

;--- The Main Loop ---------------------------------------------------------

mainloop:

  if Switch = 1 then
    Ledpower = 1                    ' Turn ON Led
    pause 200                       ' Debounce
    Ledpower = 0                    ' Turn it back OFF
  endif

  Goto mainloop

end

'---[INT - interrupt handler]---------------------------------------------------
ExternalInterrupt0:
  if wiperb = 1 then
    if leds.7 = 0 then
      LEDS = LEDs << 1              ' Leds blink counter-clockwise
    endif
  else
    if leds.0 = 0 then
      leds = leds >> 1              ' Leds blink clockwise
    endif
  endif

  PortA = leds
  pause 100
@ INT_RETURN

I used both 0.01uF and 0.1uF caps to improve debounce and wired the C pin straight to Vss (only check wiper A and B). This is the recommended circuit by the manufacturer:



Robert

[Ioannis]

Nice try Robert.

I only object to the use of Pause 100 inside the ISR.

Ioannis

[Demon]

Nice try Robert.

I only object to the use of Pause 100 inside the ISR.

Ioannis

I had first added PAUSE to reduce jitter, the only debounce I could think of on short notice. But adding 0.1uF caps as suggested in this thread was the key. I left the 0.01uF caps in, they can't hurt.

I now removed the PAUSE and it works even better (faster response time).

Thanks!

Robert