RTC on dsPIC33F

Hi All

I hope someone can help me here.  I've tried Microchip, but maybe I'm
not explaining things well enough.  I have a board which has a
32.768KHz crystal directly connected to the SOSCI/SOSCO pins on the
dsPIC.  After setting up the configuration bits correctly, for running
internal FRC w/PLL, I wrote the program below, using some bits from
Microchip demos, and programmed the device, but I cannot get it to
call the ISR when the watch crystal activates the  SOSCI pin.  I have
made it that it turns on a relay when in the routine, and off when
back in the main loop.  I can get it to go into the interrupt routine
when I use the internal oscillator as the timer device, but not the
external crystal.

I have tried every example I can find, even code direct to me from
microchip tech support but nothing works, yet all other aspects of the
chip work perfectly, I have tcp/ip / USB / SD MMC all running of the
chip, all I need is a RTC.  All pointers, sugesstion, etc. would be
great.  I have other code, which I can post if needed, but the code
below would be the best for myself to get working.  Excuse bad coding,
but I'm new to PIC.

TIA for all help

Russ

; CODE BEGINS

.include "p33FJ256GP506.inc"

	.global	__reset
	.global __T1Interrupt

	.global _wreg_init
	.global _timer_init
	.global _enSecOsc

	.section .text

; The following code example will enable Timer1 interrupts,
; load the Timer1 Period register and start Timer1.
; When a Timer1 period match interrupt occurs, the interrupt
; service routine must clear the Timer1 interrupt status flag
; in software.

__reset:
    MOV #__SP_init, W15       ;Initalize the Stack Pointer
    MOV #__SPLIM_init, W0     ;Initialize the Stack Pointer Limit
Register
    MOV W0, SPLIM
    NOP                       ;Add NOP to follow SPLIM initialization

    ; Setup relay for testing interrupt
    BCLR TRISF,#TRISF4
    BCLR LATF,#LATF4

    CALL _wreg_init          ;Call _wreg_init subroutine
    CALL _timer_init          ;Timer initialization, and Port setup
    CALL _enSecOsc        ; Enable secondary oscillator

done:
    BSET LATF,#LATF4   ; Turn off relay
    BRA     done              ;Place holder for last line of executed
code

;..............................................................................
;Subroutine: Initialization of W registers to 0x0000
;..............................................................................

_wreg_init:
    CLR W0
    MOV W0, W14
    REPEAT #12
    MOV W0, [++W14]
    CLR W14
    RETURN

;..............................................................................
; Timer Initialization
;..............................................................................

_timer_init:
	CLR T1CON 		; Stops the Timer1 and reset control reg.
	CLR TMR1 		; Clear contents of the timer register

	MOV #0x8000, w0       ; Load the Period register, -=12/04/03 RW:
changed from 0xFFFF=-
	MOV w0, PR1 		; with the value 0x8000 - 32768

	BCLR T1CON, #TCKPS0	; Load Prescaler
	BCLR T1CON, #TCKPS1	; with 00 = 1:1

	BSET IPC0, #T1IP0 	; Setup Timer1 interrupt for
	BCLR IPC0, #T1IP1 	; desired priority level
	BCLR IPC0, #T1IP2 	; (this example assigns level 1 priority)
	BCLR IFS0, #T1IF 	; Clear the Timer1 interrupt status flag
	BSET IEC0, #T1IE 	; Enable Timer1 interrupts

	BSET T1CON, #TCS	; External Clock Source
	BSET T1CON, #TON 	; Start Timer1

	RETURN

;..............................................................................
; Enable secondary oscillator
;..............................................................................
_enSecOsc:
	;OSCCONL(Low byte) Unlock Sequence
	MOV #OSCCONL, w1
	MOV.b #0x02, w0
	MOV #0x46, w2
	MOV #0x57, w3
	MOV.b w2, [w1]
	MOV.b w3, [w1]
	MOV.b w0, [w1]           ; Enable Sec Osc
   	RETURN

;..............................................................................
; Example code for Timer1 ISR
;..............................................................................

__T1Interrupt:
	PUSH.D	W4
	BCLR LATF,#LATF4     ; TURN ON RELAY
	BCLR IFS0, #T1IF 	 ; Reset Timer1 interrupt flag
	POP.D W4
	RETFIE 			      ; Return from ISR

.end

; CODE ENDS

fatbald1 wrote:
> 
> I hope someone can help me here.  I've tried Microchip, but maybe
> I'm not explaining things well enough.  I have a board which has
> a 32.768KHz crystal directly connected to the SOSCI/SOSCO pins on
> the dsPIC.  After setting up the configuration bits correctly,
> for running internal FRC w/PLL, I wrote the program below, using
> some bits from Microchip demos, and programmed the device, but I
> cannot get it to call the ISR when the watch crystal activates
> the SOSCI pin.  I have made it that it turns on a relay when in
> the routine, and off when back in the main loop.  I can get it to
> go into the interrupt routine when I use the internal oscillator
> as the timer device, but not the external crystal.
> 
> I have tried every example I can find, even code direct to me
> from microchip tech support but nothing works, yet all other
> aspects of the chip work perfectly, I have tcp/ip / USB / SD MMC
> all running of the chip, all I need is a RTC.  All pointers,
> sugesstion, etc. would be great.  I have other code, which I can
> post if needed, but the code below would be the best for myself
> to get working.  Excuse bad coding, but I'm new to PIC.
> 
> ; CODE BEGINS
> 
> .include "p33FJ256GP506.inc"
> 
>         .global __reset
>         .global __T1Interrupt
> 
>         .global _wreg_init
>         .global _timer_init
>         .global _enSecOsc
> 
>         .section .text
> 
> ; The following code example will enable Timer1 interrupts,
> ; load the Timer1 Period register and start Timer1.
> ; When a Timer1 period match interrupt occurs, the interrupt
> ; service routine must clear the Timer1 interrupt status flag
> ; in software.
> 
> __reset:
>     MOV #__SP_init, W15       ;Initalize the Stack Pointer
>     MOV #__SPLIM_init, W0     ;Initialize the Stack Pointer Limit
> Register
>     MOV W0, SPLIM
>     NOP                       ;Add NOP to follow SPLIM initialization
> 
>     ; Setup relay for testing interrupt
>     BCLR TRISF,#TRISF4
>     BCLR LATF,#LATF4
> 
>     CALL _wreg_init          ;Call _wreg_init subroutine
>     CALL _timer_init          ;Timer initialization, and Port setup
>     CALL _enSecOsc        ; Enable secondary oscillator
> 
> done:
>     BSET LATF,#LATF4   ; Turn off relay
>     BRA     done              ;Place holder for last line of executed
> code
> 
> ;..............................................................................
> ;Subroutine: Initialization of W registers to 0x0000
> ;..............................................................................
> 
> _wreg_init:
>     CLR W0
>     MOV W0, W14
>     REPEAT #12
>     MOV W0, [++W14]
>     CLR W14
>     RETURN
> 
> ;..............................................................................
> ; Timer Initialization
> ;..............................................................................
> 
> _timer_init:
>         CLR T1CON               ; Stops the Timer1 and reset control reg.
>         CLR TMR1                ; Clear contents of the timer register
> 
>         MOV #0x8000, w0       ; Load the Period register, -=12/04/03 RW:
> changed from 0xFFFF=-
>         MOV w0, PR1             ; with the value 0x8000 - 32768
> 
>         BCLR T1CON, #TCKPS0     ; Load Prescaler
>         BCLR T1CON, #TCKPS1     ; with 00 = 1:1
> 
>         BSET IPC0, #T1IP0       ; Setup Timer1 interrupt for
>         BCLR IPC0, #T1IP1       ; desired priority level
>         BCLR IPC0, #T1IP2       ; (this example assigns level 1 priority)
>         BCLR IFS0, #T1IF        ; Clear the Timer1 interrupt status flag
>         BSET IEC0, #T1IE        ; Enable Timer1 interrupts
> 
>         BSET T1CON, #TCS        ; External Clock Source
>         BSET T1CON, #TON        ; Start Timer1
> 
>         RETURN
> 
> ;..............................................................................
> ; Enable secondary oscillator
> ;..............................................................................
> _enSecOsc:
>         ;OSCCONL(Low byte) Unlock Sequence
>         MOV #OSCCONL, w1
>         MOV.b #0x02, w0
>         MOV #0x46, w2
>         MOV #0x57, w3
>         MOV.b w2, [w1]
>         MOV.b w3, [w1]
>         MOV.b w0, [w1]           ; Enable Sec Osc
>         RETURN
> 
> ;..............................................................................
> ; Example code for Timer1 ISR
> ;..............................................................................
> 
> __T1Interrupt:
>         PUSH.D  W4
>         BCLR LATF,#LATF4     ; TURN ON RELAY
>         BCLR IFS0, #T1IF         ; Reset Timer1 interrupt flag
>         POP.D W4
>         RETFIE                        ; Return from ISR
> 
> .end
> 
> ; CODE ENDS

AFAICS there is no loop anywhere to repeat the test.  However if
the BRA done is the actual loop, there is no time for the relay to
close.

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CBFalconer wrote:
>
> AFAICS there is no loop anywhere to repeat the test.  However if
> the BRA done is the actual loop, there is no time for the relay to
> close.
>

Sorry I forgot to include the delay loop in the timer ISR.  I used
this to hold the relay while I check with the scope, just incase the
debugger was missing the breakpoint within the routine, you never
know.

Thanks for your reply.

Hi

It turned out to be a hardware problem.  The engineer placed a 1M
resistor between the crystal and gnd and it worked perfect.

Russ