Question for Mr. Darrel Taylor and Mister-e Timer1 Reload

[pedja089]

10Hz interrupt is problem to derive from 32768Hz. 16Hz or 32Hz etc isn't problem. To get 1sec just count 16 interrupts, and that is all.
I posted RTC code, with external crystal, 32 interrupts per second, and it consumes less than 10uA if you put pic in sleep mode.

[mikebar]

NICE!
Where I can see that code?

Thank you.

[pedja089]

I can't find that topic...
Here is cut/paste from my code for PIC18LF14K50

        DEFINE  OSC 4         
        Define  INTHAND myint    ' Define interrupt handler
        DEFINE  NO_CLRWDT 1

        OSCCON=%01010110
        OSCCON2.2=0
        OSCTUNE.7=1
        OSCTUNE.6=1
        REFCON0=0
        REFCON1=0
        ADCON1=0
        ADCON2=0
        ANSEL =0           
        ANSELH=0
        CM1CON0=0
        CM2CON0=0
        SRCON0=0
        SRCON1=0
        WPUA=0
        WPUB=0
        WDTCON=0   
        SLRCON=0           
        RCON.7=0
        RCON.6=0   
        UCON=0  
        IOCA=0
        IOCB=0
        T0CON=0
        T1CON=%00001111  
        T2CON=0
        T3CON=%00000110
        INTCON=192  
        INTCON2=0  
        INTCON3=0 
        PIR1=0
        PIR2=0
        PIE1=1
        PIE2=0
        IPR1=0
        IPR2=0
        porta=0
        portb=0
        portc=0
        trisa=255
        trisb=255
        trisc=255




'RTC_________________________
Seconds        VAR BYTE bankA  
Minutes        VAR Byte bankA       
Hours          var byte bankA
   



 
 clear

GoTo OverInt  ' jump over the interrupt handler and sub
ASM                  
myint 
 movlb .0
 ;If PIR1.0 =1 then
 BTFSS PIR1,0 
 GOTO End_RTC 
 MOVLW .252 ; TMR1H=252
 MOVWF TMR1H
 CLRF PIR1 ; Clear TMR1 int flag
 INCF _Ticks,F 
 ;if ticks>31 then
 MOVLW .31
 CPFSGT _Ticks  
 GOTO End_RTC   
    INCF _Seconds,F  
    CLRF _Ticks
    ; if seconds > 59 then
    MOVLW .59         
    CPFSGT _Seconds   
    GOTO End_RTC   
       CLRF _Seconds   
       INCF _Minutes,F
       ;if minutes > 59 then
       MOVLW .59         
       CPFSGT _Minutes   
       GOTO End_RTC      
          CLRF _Minutes
          INCF _Hours,F
          ;if hours > 23 then 
          MOVLW .23       
          CPFSGT _Hours   
          GOTO End_RTC    
              CLRF _Hours
End_RTC                                      
;Do your other stuff here
 retfie  FAST  
ENDASM  
OverInt:

Main:
@ Sleep
'program starts here 32 times in sec
goto Main

This is example for PIC's that have fast return stack, and saves and restores WREG, STATUS and BSR registers...

[mikebar]

Thank you a lot.

[pedja089]

Just one more thing that I had to deal with...
Selection of crystal and capacitors from OSC pins to ground is critical to get accurate clock. I tried one by one from 10 to 47pF, and best results are with 47pF. But that will depend from board layout and used crystal.
My suggestion is that you buy a lot of crystals, and select appropriate capacitor for it. And use that combination from now.

[mikebar]

Thank you pedja089,
looks to be a challenge...

[pedja089]

I'm glad that I could help.
Good luck