New approach to Rotary Encoder

[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.

[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...