how to read ky40 mechanical encoder ?

[richard]

ToggleLED1:
     if b=0 then cnt=cnt-1
     IF B=1 THEN CNT=CNT+1
 @ INT_RETURN

I found that strategy gave quite disappointing results , was jerky missed counts and had sudden and unexpected direction reversals. there are better ways

[iw2fvo]

I am sorry Richar for having posted the file that is not the final one:
please change the following:

A VAR PORTD.0 ' encoder A PHASE
shAll be:
A VAR PORTB.0

This is the interrupt input !

I would be happy to know ...
Thanks and regards,
Ambrogio

[iw2fvo]

I did capture the output of the terminal printout for a better check.
There are about 200 changes of the cnt obtained by "manually" turning the encoder knob on my control panel. Probably sometims cw and ccw.
I noted very few spikes : I am not shure if they are due to the time required for the serial port output or to the encoder software.
Any improvement to the program is very much appreciated.
I am really searching for a good solution.
Thanks
regards,
Ambrogio

[richard]

I do it this way

enc pins must be sequential and on same port
both enc pins must be able to generate an interrupt (ioc on neg and pos edge is best , ioc, rac,rbc on neg or pos edge will work as will int0 int1)
enc pins must be pulled up (10k) and have 0.1uF filter caps

I have an asm version that's 100 bytes smaller and has about 1 tenth of the irq latency and is much faster too

'****************************************************************
'*  Name    : rotary encoder.BAS                                *
'*  Author  : richard                                           *
'*  Notice  : Copyright (c) 2013                                *
'*          : All Rights Reserved                               *
'*  Date    : 9/4/2013                                          *
'*  Version : 1.0    16f1825                                    *
'*  Notes   :  enca porta.2 encb porta.3                        *
'*          :   note mclr disabled ,full quad decode            *
'****************************************************************
  
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_OFF  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG
  
 
include "dt_ints-14.bas"
include "REENTERPBP.bas"
 
asm
INT_LIST macro
      INT_HANDLER IOC_INT, _enc_isr,pbp,NO
      endm
 INT_CREATE
ENDASM    
 
DEFINE OSC 32
 
 
 
 
   OSCCON=$70
   ANSELA=0
   
   OPTION_REG.6=0
 
   ev    VAR BYTE bank0
   cnt   VAR WORD bank0
   TMP   VAR BYTE bank0
   enca  VAR porta.2 
   encb  VAR porta.3
   TRISA = 111110
  
   lata.0=1
   IOCAP=12    ;enca porta.2 encb porta.3  pos edge trigger
   IOCAN=12    ;enca porta.2 encb porta.3  neg edge trigger
    
    
   pause 4000 
   
   serout2 PORTA.0,84,[ "ready",13,10]
   IOCAF=0
   
   INTCON=$C8
   
   
   
mainloop:  
 
 serout2 PORTA.0,84,[13,10, "C",#CNT]
 pause 1000
 
 goto mainloop
    
 
    
 
enc_isr:
    

ev=ev<<2              ;shift last reading into position
ev=ev|((porta&12)>>2)  ;read enc pins 2,3  mask off others then  combine this reading with last reading
LOOKUP (ev&$f),[0,255, 1, 0, 1, 0, 0, 255, 255, 0, 0, 1, 0, 1, 255, 0],tmp ;lookup the decision matrix
if tmp then         ; decide to inc , dec or ignore 
 if tmp.7 then
   cnt=cnt-1
 else
    cnt=cnt+1
 endif
endif
intcon.0=0                   ; clean up and exit
iocaf=0
@ INT_RETURN

[iw2fvo]

Thanks Richard for the code.
I am just a little bit busy on these days and so I plan to try your code on next days.
As you have seen I am using pic18f452: Is your code applicable to this micro ?
If no, what should I modify or adapt ?
Thanks
Regards,
Ambrogio

[richard]

for a pic18f452 you need to use RBC_INT for best results and pins portb.4,5 or portb.6,7 or portb.5,6

this line needs to match chosen p1ns

ev=ev|((porta&12)>>2) ;read enc pins 2,3 mask off others then combine this reading with last reading

for pins portb.4,5 it would be

ev=ev|((portb&48)>>4)

INT_LIST macro
      INT_HANDLER IOC_INT, _enc_isr,pbp,NO
      endm
 INT_CREATE

would be

INT_LIST macro
      INT_HANDLER RBC_INT, _enc_isr,pbp,NO
      endm
 INT_CREATE

IOCAP=12 ;enca porta.2 encb porta.3 pos edge trigger
IOCAN=12 ;enca porta.2 encb porta.3 neg edge trigger
IOCAF=0
INTCON=$C8

would be

dummy_var = portb
INTCON=$C8

any references to IOCAF need to be deleted , trisb must be appropiate

[iw2fvo]

Hi Richard,
I am going to modify my previous program with your indications.
Probably I did something wrong and it is not working.
I am attaching the full code : could you please have a look of it ?
Thanks again for the assistance
regards,
Ambro