Instant Interrupts - Revisited

[Darrel Taylor]

The Edge Select bits are located in the INTCON2 register of the 4550.

They are Rising edge by default, so for INT1 Falling edge...

INCON2.5 = 0  ; External INT1 on Falling edge

<br>

[precision]

I set INTCON bit but not working on falling edge.

' chip PIC18F4550
DEFINE OSC 48
INCLUDE "MODEDEFS.BAS"
include "MYLCD.BAS"
CMCON = 7
ADCON1 = 15
CVRCON = %00000000 'CVref turned off

TRISB = %11111111
w0 var word
pause 500

'-------------------------[ INT0 Interrpt setting ] -----------------------------
INCLUDE "DT_INTS-18.bas"     ; Base Interrupt System
INCLUDE "ReEnterPBP-18.bas"     ; Include if using PBP interrupts
ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler    INT0_INT,  _ToggleLED1,   PBP,  yes
        INT_Handler    INT1_INT,  _ToggleLED2,   PBP,  yes                
    endm
    INT_CREATE               ; Creates the interrupt processor
INCON2.5 = 0  ; External INT1 on Falling edge
ENDASM

@   INT_ENABLE   INT0_INT     
@   INT_ENABLE   INT1_INT
'__________________________________________________________________________________


start:  lcdout $fe,1
        lcdout "count = ",dec5 w0
        pause 200
        goto start



ToggleLED1:
            w0 = w0+1
            @ INT_RETURN
            
ToggleLED2:            
             w0 = w0+1
            @ INT_RETURN

[Darrel Taylor]

It's a regular PBP statement, but it's in an ASM block.

Move it outside the block and it should work better.
<br>

[precision]

Syntex error

Ohh. Sory sir, I cut yout code and paste, I don't see there are INCON

Thanks sir, It's Working

[Darrel Taylor]

Oops!
<br>

[srspinho]

Hi Darrel,

some days ago, I was trying to measure the "ON time" of my car´s gasoline injectors (one of the 4)

I´m using a 16F877 @ 10 Mhz, and I´m using the Timer0 as a 250 ms counter and Timer1 as a pulse counter, I ran out of possibilities of new measurements.

Bruce told me that I should use a new device with more timers available, like the 18F4431 (or similar).
The problem is : This device (or similar) is not available here in Brazil, and Microchip do not send samples to Brazil.

I was reading this post about the interrupts and decided to ask :

Is that possible to read the pulses on Timer1 on a fixed time interval (so, I would have the car´s speed and the mileage) and measure the injector on-time (so I would have the consumption) with the instat interrupts running on a 16f877 ?

Thanks !

Sergio

[Darrel Taylor]

Sure you can.

I'd use the Capture mode of the CCP modules using Timer1, for the ON time.

Timer 2 can be the timebase used to count the speedometer pulses on the INT (external interrupt) pin.

And the same signal from the Injector can be fed to T0CKI, so Timer 0 can count the RPM's too.

Speed, Distance, Consumption and Tachometer.
<br>