Elapsed timer not working as expected at 64MHz

[richard]

now I'm confused

Well that toggle from Sheldon confirms DT's is not working perfectly at 64MHz.

or
Well that toggle from Sheldon confirms DT's is working perfectly at 64MHz.

ps

IF LATD.3 = 0 THEN ' debug
LATD.3 = 1
ELSE
LATD.3 = 0
ENDIF

can be replaced with

latd.3=!latd.3

lets not have too much unnecessary overhead in the interrupt

[Demon]

now I'm confused

or
Well that toggle from Sheldon confirms DT's is working perfectly at 64MHz.

DT's Elapsed include doesn't work perfectly at 64MHz (1 tick = 2.5ms), Sheldon's modified version does (1/100th = 10ms). Sheldon has added a new variable. I'm cleaning up the new include now to put it on the forum, somewhere.

Robert

[richard]

you may like to re-examine that I just tried it on a pic1845k20 @64 MHz and the int is @2.5mS as expected , sheldons mod just adds 100th capability doesn't it ?

the seconds inc on every 400th interrupt the ticks are not meant to be 10mS

[Demon]

From http://web.archive.org/web/201206151...8/elapsed.html

The time is kept in the variables:
--------------------------------------------------------------------------------

Ticks var byte ' 1/100th of a second
Seconds var byte ' 0-59
Minutes var byte ' 0-59
Hours var byte ' 0-23
Days var word ' 0-65535

But a tick is not 2.5ms.

Robert

[Demon]

you may like to re-examine that I just tried it on a pic1845k20 @64 MHz and the int is 2.5mS as expected , sheldons mod just adds 100th doesn't it

the ticks only inc on every 4th interrupt

What happens when you start/stop the timer after 5 ticks using the original include?

I get this using the new include:

MainProgram:

    if T1CON.0 = 0 then
        PortD.3 = 1
        GOSUB StartTimer
    endif

    if OneHundreth = 5 then
        PortD.3 = 0
        GOSUB StopTimer                    ' Stop the Elapsed Timer
        GOSUB ResetTime                     ' Reset Time to  0d-00:00:00.00
    endif

    goto MainProgram

Robert

[richard]

its a clock not a stopwatch , if you really need to measure wee small times like that there are better ways.
to get the fractional part of the seconds multiply t1post with ticks and / 4

[Demon]

New version of Darrel Taylor's Elapsed include for 64MHz:

'***************************************************************************
'*  Name    : Elapsed_INT-18.bas                                           *
'*  Author  : Darrel Taylor                                                *
'*  Date    : JUL 11, 2006 : 7/11/2010 : Dec 23, 2014                      *
'*  Version : 1.3                                                          *
'*  Notes   : Must have DT_INTS-18.bas loaded first                        *
'*   ver 1.2: Now works at any OSC frequency without using the prescaler   *
'*   ver 1.3: will work with 64MHz thanks to Sheldon                       *
'*            New field ONEHUNDRETH is now used instead of TICKS           *
'***************************************************************************
DISABLE DEBUG

; syntax =     Handler  IntSource,        Label, Type, ResetFlag?
DEFINE  Elapsed_Handler  TMR1_INT,  _ClockCount,  asm,  yes
; the above define can be used in the INT_LIST macro, if desired (optional)

Ticks            VAR BYTE   ; Counts timer Overflows
OneHundreth      VAR BYTE    ; New field for 64MHz
;T1Post           VAR BYTE   ; Timer1 postscaler
Seconds          VAR BYTE
Minutes          VAR BYTE
Hours            VAR BYTE
Days             VAR WORD

OneHundrethChanged     VAR BIT    ; New field for 64MHz
SecondsChanged   VAR BIT    ; idicates that the value has changed
MinutesChanged   VAR BIT
HoursChanged     VAR BIT
DaysChanged      VAR BIT

GOSUB ResetTime             ; initialize the Elapsed Timer

Goto OverElapsed            ; skip over the routines

' -------------- calc timer reload Constants -------------------------------
ASM
T1PS = 1                             ; start with 1:1 postscaler
TimerConst = ((OSC*1000000)/4/100)   ; how many timer ticks will it take
  while TimerConst > 65400           ; if it's more than the timer can count
T1PS = T1PS * 2                      ;   double the postscaler
TimerConst = TimerConst / 2          ;   halve the count
  endw
TimerConst = 65536 - TimerConst + 8  ; final reload value
  
  
; -----------------  ADD TimerConst to TMR1H:TMR1L -------------------------
ADD2_TIMER   macro
    BCF     T1CON,TMR1ON, 0       ;  1 Turn off timer
    MOVLW   LOW(TimerConst)       ;  1
    ADDWF   TMR1L,F, 0            ;  1    
    BTFSC   STATUS,C              ;  1/2
    INCF    TMR1H,F, 0            ;  1
    MOVLW   HIGH(TimerConst)      ;  1
    ADDWF   TMR1H,F, 0            ;  1
    endm

; -----------------  ADD TimerConst to TMR1H:TMR1L and restart TIMER1 ------
RELOAD_TIMER  macro
    ADD2_TIMER
    BSF     T1CON,TMR1ON, 0       ;  1   Turn TIMER1 back on  (8 cycles)
    endm

; -----------------  Load TimerConst into TMR1H:TMR1L ----------------------
LOAD_TIMER  macro
    MOVE?CT  0, T1CON,TMR1ON
    MOVE?CB  0, TMR1L
    MOVE?CB  0, TMR1H
    ADD2_TIMER
    endm
ENDASM

' ------[ This is the Interrupt Handler ]-----------------------------------
T1PS  CON EXT
ClockCount:
@ RELOAD_TIMER                   ; Reload TIMER1
Ticks = Ticks  + 1                      ; each tick is 2.5ms 
'       IF LATD.3 = 0 THEN                  ' used to debug to confirm 2.5ms
'          LATD.3 = 1
'       ELSE 
'          LATD.3 = 0
'       ENDIF   
  if ticks // T1PS = 0  THEN      ' if modulas of tips (4) = 0 
'       IF LATD.3 = 0 THEN                  ' used to debug to confirm 10ms
'          LATD.3 = 1
'       ELSE 
'          LATD.3 = 0
'       ENDIF   
          OneHundreth = OneHundreth + 1   ; each 1/100th is 10ms
          OneHundrethChanged = 1
          IF OneHundreth  = 100 THEN
              OneHundreth = 0
'    Ticks = Ticks + 1
'    IF Ticks = 100 THEN
'       Ticks = 0
'       T1Post = T1Post + 1
'       IF T1Post = T1PS THEN
'           T1Post = 0
           Seconds = Seconds + 1
           SecondsChanged = 1
           IF Seconds = 60 THEN
              Seconds = 0
              Minutes = Minutes + 1
              MinutesChanged = 1
           ENDIF
           IF Minutes = 60 THEN
              Minutes = 0
              Hours = Hours + 1
              HoursChanged = 1
           ENDIF
           IF Hours = 24 THEN
              Days = Days + 1
              DaysChanged = 1
              Hours = 0
           ENDIF
       ENDIF
    ENDIF
@ INT_RETURN                     ; Restore context and return from interrupt

'-----====[ END OF TMR1 Interrupt Handler ]====-----------------------------

StartTimer:
    T1CON = 1                    ; 1:1, FOSC4, TMR1ON
RETURN

; --------------------------------------------------------------------------
StopTimer:
    T1CON.0 = 0                  ; Turn OFF Timer1
RETURN

; --------------------------------------------------------------------------
BitSave  VAR  BIT

ResetTime:
    BitSave = T1CON.0            ; Save TMR1ON bit
@   LOAD_TIMER                   ; Load TimerConst
    T1CON.0 = BitSave            ; Restore TMR1ON bit
;    T1Post = 0                   ; clear the postscaler
    Ticks = 0
    OneHundreth = 0
    Seconds = 0
    Minutes = 0
    Hours = 0
    Days = 0
    OneHundrethChanged = 1
    SecondsChanged = 1           ; indicate everything has changed
    MinutesChanged = 1           ; so that 00:00:00 is processed
    HoursChanged = 1
    DaysChanged = 1
RETURN


OverElapsed:
ENABLE DEBUG

New field OneHundreth (10ms) replaces Tick (2.5ms at 64MHz).



(Remove .TXT suffix)
Elapsed_INT-18_64MHz.bas.txt

Robert