Troubled with Instant Ints and TMR2

**mister_e** · - 3rd October 2007, 23:13

is it me or you should use TMR2 instead of PR2?

Try TMR2=TMR2+138 (or something around it) and toggle a led to know what happen

i'm a bit rusty here... and i can't test it... damn!

**mister_e** · - 3rd October 2007, 23:27

Joe,
no you didn't miss something, probably because Josuetas got a error message about a wsave beyond ram end or something like that.

So my guess is that he comment out the offending line in those files and use a specific name for it.

**Josuetas** · - 3rd October 2007, 23:32

Joe S.

Modifications...
i have a DT for 628A since it needs bank modification from 877A.
In the second one i am modifing Elapsed to interrupt every 125us it is not meant for timing but for interrupting. All i did was modifing the timerconst to be $FFA7 in the case of 4Mhz Osc. I am not using this anyway you can see the TMR1 interrupt is not defined for elapsed interrupt, only TMR2.

mister_e

If i get this right, and from the datasheet the timer2 interrupts when Tmr2 reaches PR2 value, tmr2 "should" go to 0 after this, BUT it seemed not TO i had to turn TMR2= 0 in the interrupt routine, Otherwise i was getting weird interruptions (watched it on my osciloscope)

Still cant get my 125us interrupt with 4Mhz internal OSC this should be possible unless DT´s routines take more than 125 instructions to work (just my guess),.. Patience....Again i am sure HE knows

**mister_e** · - 3rd October 2007, 23:35

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

Sorry

**Josuetas** · - 4th October 2007, 00:00

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:

Code:

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** · - 4th October 2007, 02:11

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

Code:

        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

Code:

        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** · - 4th October 2007, 15:36

Originally Posted by mister_e

Code 1 with ON INTERRUPT

Code:

        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.

**Darrel Taylor** · - 4th October 2007, 07:31

Originally Posted by Josuetas

Still cant get my 125us interrupt with 4Mhz internal OSC this should be possible unless DT´s routines take more than 125 instructions to work (just my guess),.. Patience....Again i am sure HE knows

This page might explain it.
http://darreltaylor.com/DT_INTS-14/kudos.html
Especially the last paragraph.
<br>

**Josuetas** · - 4th October 2007, 15:29

So Darrel if i made this with just an ASM interrupt i would be able to get my 125uS since i wouldnt need the Reenter Context Saving...

BUT please o please can you help me?..

I use to get to this point where: i dont know any assembler!!!
even worst
A bit Array of 120 samples in Assembler .... mmm..... mmmmm....

By the way would you consider (in my case) the pauseus 125 Take Sample option?

Please some lead to solve this matter.

Thanks again

DJC

**Darrel Taylor** · - 4th October 2007, 17:01

>> So Darrel if i made this with just an ASM interrupt i would be able to get my 125uS since i wouldnt need the Reenter Context Saving...
Correct.

>> A bit Array of 120 samples in Assembler .... mmm..... mmmmm....
In ASM, you would just shift the bits into a byte var. After 8 bit's move to the next byte. After 15 bytes you're done.

>> By the way would you consider (in my case) the pauseus 125 Take Sample option?

YES!
Your program just sits in a loop anyways, waiting for the sample to finish.
No need to use interrupts, if it's not doing anything in the first place.

Or, you can still use the timer. Just poll the TMR2IF Flag.
<br>

**Josuetas** · - 4th October 2007, 17:45

I will keep working on the interrupt option... This is supposed to detect DTMF (we talk about it before) so for it to work in the background of anything else is the best choice.

Everything is so complicated in ASM!.. thanks god there is picbasic.

**Darrel Taylor** · - 4th October 2007, 20:21

Here's a quick untested stab at an ASM handler.

Change the Handler type to ASM

Code:

Samples      VAR BYTE[15] BANK0 SYSTEM
SamplePTR    VAR BYTE     BANK0 SYSTEM
SamplesAddr  CON EXT
@SamplesAddr = Samples
BitCount     VAR BYTE     BANK0 SYSTEM
ByteCount    VAR BYTE     BANK0 SYSTEM
FlagSample   VAR BIT
TMR2ON       VAR T2CON.2

;----[Start getting the 120 samples]------------------------------------------
GetSamples:
    FlagSample = 0
    SamplePTR = SamplesAddr
    ByteCount = 15
    BitCount  = 8
    PR2 = 125 : TMR2 = 0 : TMR2ON = 1
return
    
;----[TMR2 Handler]-----------------------------------------------------------
ASM
Sample
    MOVE?BB  SamplePTR, FSR      ; Load FSR with pointer to array
    MOVE?TT  CMCON,7, STATUS,C   ; Put sample in carry flag
    rrf      INDF, F             ; Shift in the sample bit
    decfsz   BitCount, F         ; Are all 8 bits in ?
    goto     Int_Done            ;   NO, done for now
    MOVE?CB  8, BitCount         ;   Yes, reset bitcount
    incf     SamplePTR, F        ;     Point to next byte
    decfsz   ByteCount, F        ; Are all 15 bytes done ?
    goto     Int_Done            ;   NO, done for now
    MOVE?CT  1, _FlagSample      ;   Yes, Indicate - Samples Complete
    MOVE?CT  0, _TMR2ON          ; stop the timer
Int_Done
    INT_RETURN
ENDASM

Thread: Troubled with Instant Ints and TMR2

Thread Tools

Search Thread

Display

Hybrid View

Thanks for your replies

I just doesnt work.. Impossible?

Maybe this would work better tha Instant Interrupts here!

Ok now thats bad news

Thanks for your advise Darrel

Members who have read this thread : 1

Bookmarks

Bookmarks

Posting Permissions