Probe to read quadrature encoder with DT_INT need help

[phoenix_1]

Acetronics your help is 100% work.
Thank's many thanks man.
And one question more...how DT interupt can be fast ?

[Acetronics2]

And one question more...how DT interupt can be fast ?

Hi,

I do not know exactly ...

but it's roughly the time to save and restore all the PBP variables in use, added to the "classic" ASM interrupts time ...

You can Use the MPLAB SIM ... You will have a very good idea !

Alain

[phoenix_1]

DT_INT with TIMER_1 and led blink work 100% on 16f877 when I test it but:

define OSC 20
ADCON1 = 7                       
TRISB = %00000011
INTCON = %10001000 
LED1 VAR PORTA.0
LED2 VAR PORTA.1
LOW LED1 
low LED2 

INCLUDE "DT_INTS-14.bas" 
INCLUDE "ReEnterPBP.bas" 
ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
    INT_Handler RBC_INT, _TEST, PBP, yes
    endm
    INT_CREATE ; Creates the interrupt processor
ENDASM
@   INT_ENABLE RBC_INT 

Main:
PAUSE 1
GOTO Main

'---[RBC_INT - interrupt handler]------------------------------------------

TEST:
high led1
high led2
@       INT_RETURN

Dont want to work for me...why ?

[Acetronics2]

Just try PortB.7 and PortB.6 ...

and read the '877 Databook , Interrupts section :

WHICH are the 4 pins that create "interrupts on change" ???

HOW to avoid the " Mismatch condition " ???

Alain

[phoenix_1]

These code count pulses from one pin of quadrature encoder good and fast.
It use RB0 INT very good.
Now I need idea to implement full reading quadrature encoder A and B inputs with count of pulses and direction indication..
Encoder is with 500 pulses per full revolution.
How - need idea..?
Procesor 16F877 @ 20MHz

define OSC 20
DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 64  ' 19200 Baud @ 20MHz, 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

ADCON1 = 7                       
TRISB = %00000011
a var word
a = 0
INTCON = %10010000 ; Enable INTE RB0 interrupt $90 
INCLUDE "DT_INTS-14.bas" 
INCLUDE "ReEnterPBP.bas" 
ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
    INT_Handler INT_INT,    _TEST,  PBP, yes
    endm
    INT_CREATE ; Creates the interrupt processor
ENDASM

Main: 
if a >= 5000 then
a = 0
endif
hserout [ dec a ]
pause 100
GOTO Main

'---[INT_INT - interrupt handler]------------------------------------------

TEST:
a = a + 1
@   INT_RETURN

Regards Robert

[aratti]

Connect encoder channel A to portB.0 (I assume you already have it) and channel B to portB.1. Since channel A is out of phase on channel B turning your encoder CW channel A will be high before channel B and turning it CCW channel B will be high first.

In your interrupt handler check the above conditions

If portB & %00000011 = 1 Then
a = a + 1
CW = 1
Else
a = a - 1
CW = 0
Endif

If variable CW is 1 then your motor is turning clockwise if CW = 0 then is turning counterclockwise, while word variable a will contain the updated count.

Al.

[aratti]

I have forgotten to say, in my previuos post, that the code snippet is not a quadrature count, and it counts only channel A, while Channel B is used only for direction. So total count per encoder turn will be n/2.

To get a quadrature count you need to detect the rising and falling edges of the square waves, thing that is not possible with the pic you have in use. To obtain the quadrature count you either need additional external logic or you have to choose a pic with the quadrature counter. (Much easier)

Al.