Troubled with Instant Ints and TMR2

[mister_e]

oups... missed the Elapsed timer... i'll read the according posts/thread about it as i never used it.

Sorry

[Josuetas]

Ok i figured out a way to measure my interrupts.

The interrupt routine simply Toggles a pin of the micro on each interrupt and i measure such pin with my oscilloscope. The frequency of sampling is wrong.

Problems:

1. The TMR2 doesnt just go back to 0 after reaching PR2 value.. i had to set it to 0 otherwise i get unwanted interrupts.

2. I cant believe this to be impossible so i made a small RX int.... when i press "1" PR increases by one.. else it goes down one, so i can sweep controlling by my keyboard. RESULT: No No it doesnt work.... i never get to my 125us interrupt it suddenly jumps back to the lower frequency after a point.

Is 125us to much to ask for 4Mhz.. teorically i would say No.. 125 instructions are a lot of instructions... and i am only sampling at this point of my software so: what could be the problem?

I cant use other OSC since i am using internal OSC and A7 pin for other purpouses... Since i am only sampling would something like pauseuS 125 : sample work?... What should be the timing consideration in this case?

i still need someting like:

Sample:
    pauseus 125
    Samples [NumSamples] = CMCON.7
    NumSamples = NumSamples + 1
    IF NumSamples = 120 THEN return
    goto Sample

How many instructions take this sub to work? i guess i have to take them into account for my timing to be correct!!!

Thanks on any help.. Interrupt 125uS 4Mhz still in need!!

[mister_e]

mmm, can you (or someone else) try the following for me? Try both with a 4 MHz and then with a 20MHz crystal. You just need to change the DEFINE OSC and the code will automatically change for you (config fuses, Prescaller and PR2). Sit a scope on PinActivar (PORTB.0) and measure the frequency. It has to be close of 4KHz

Code 1 with ON INTERRUPT

        DEFINE OSC 4   ' select 4 or 20
        PinActivar      VAR portb.0
        
        LoopCount  VAR WORD
        TMR2IF VAR PIR1.1
            
        TRISB = 0
        portb = 0
        INTCON  = %11000000
        PIE1    = %00000010
        PIR1    = %00000000
        OPTION_REG = %00000000 
        PinActivar = 0
        
@   IF (OSC==20)        
@       __config _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        pr2 = 155 
        T2CON = %00000101   ' TMR2 Prescale 1:4
@       ELSE
@       __config _XT_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        PR2 = 118
        T2CON = %00000100 ' TMR2 prescale 1:1    
@       ENDIF        

        ON INTERRUPT GOTO Sample

MAIN:
        GOTO MAIN

disable   
Sample:
        TOGGLE PinActivar
        tmr2if=0
resume  
enable

Code 2, with DT-INT

        DEFINE OSC 4 ' select 4 or 20
        
        INCLUDE "c:\pbp_prog\Include_routines\DT_INTS-14.bas"
        INCLUDE "c:\pbp_prog\Include_routines\ReEnterPBP.bas"
ASM
INT_LIST  macro    ; IntSource,    Label,  Type, ResetFlag?
        INT_Handler   TMR2_INT,  _Sample,   PBP,  YES
    endm
    INT_CREATE
ENDASM 
        PinActivar      VAR portb.0

        TRISB = 0
        portb = 0
        OPTION_REG = %00000000 

@   IF (OSC==20)        
@       __config _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        pr2 = 155           ' load tmr2 PR2 to reset every 125 uSec
        T2CON = %00000101   ' TMR2 Prescale 1:4
@       ELSE
@       __config _XT_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        PR2 = 118
        T2CON = %00000100   ' TMR2 prescale 1:1    
@       ENDIF             

@       INT_ENABLE  TMR2_INT
MAIN:
        GOTO MAIN

   
Sample:
        toggle pinactivar
@ INT_RETURN

i'm curious to knwo if there's any significant difference between the above, and how much. I feel them equal @20MHz, but some doubt on 4MHz.

Obviously this code don't do anything interesting... i'm just curious...

As i said, i can't check anything it here.

[Josuetas]

Code 1 with ON INTERRUPT

        DEFINE OSC 4   ' select 4 or 20
        PinActivar      VAR portb.0
        
        LoopCount  VAR WORD
        TMR2IF VAR PIR1.1
            
        TRISB = 0
        portb = 0
        INTCON  = %11000000
        PIE1    = %00000010
        PIR1    = %00000000
        OPTION_REG = %00000000 
        PinActivar = 0
        
@   IF (OSC==20)        
@       __config _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        pr2 = 155 
        T2CON = %00000101   ' TMR2 Prescale 1:4
@       ELSE
@       __config _XT_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF
        PR2 = 118
        T2CON = %00000100 ' TMR2 prescale 1:1    
@       ENDIF        

        ON INTERRUPT GOTO Sample

MAIN:
        GOTO MAIN

disable   
Sample:
        TOGGLE PinActivar
        tmr2if=0
resume  
enable

Mister_E i am going to test with the ON INTERRUPT way because it might work better here, i am not doing much code between Samples so this could work fine. Thanks for the idea...

The DT option as you can read at Darrels link will not work either.