DS1306 RTC Read with HC08 SPI

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Hi,
    I'm attempting to use a real-time clock (DS1306) by interfacing it with
a HC08GP32 microcontroller using the SPI.  To get my algorithm working, I am
using some of the extra RAM located in the DS1306 to write a few registers
and then attempt to read them.  It seems that the writing part works fine;
however, when I attempt to read back what I've written, I get varying
results.  I'm using CodeWarrior software for my debugging.  When I single
step thru the program, everything works fine (both write and read).
However, when I run the program (no breakpoints, I do not read all the
registers correctly.  I do believe that the write part is working...as I can
run this part fullspeed with no problem.  However, the read part does not
work full speed.  Some of my assembly code is shown here:   Any suggestions?

main:
       rsp
       mov     #$01,CONFIG1            ; disable COP watchdog
       sei
       clra
       clrx
       clr  one  ; Clear RAM variables
       clr  two
       mov  #$1D,DDRD ; Write enable MOSI,SPSCK,SS $0007
       bclr  ss,PORTD ;        CHPA must be '1'
       mov  #$08,SPCR
       mov  #$2A,SPCR        ; Enable SPI control register $0010
       mov  #$02,SPSCR     ; Set divisor for baud rate at 128 $0011
       bset  ss,PORTD         ; Activate DS1306 for read/write
       mov  #$8F,SPDR         ; Address of Control Register on DS1306
       brclr spte,SPSCR,*
       mov  #$04,SPDR         ; Enable write (bit7), enable 1Hz (bit2)
       brclr spte,SPSCR,*
       jsr  Toggle_SS             ; Reset DS1306
       mov  #$A0,SPDR         ; Address of RAM for writing
       brclr spte,SPSCR,*
       mov  #$13,SPDR     ; Write to $A0 on DS1306
       brclr spte,SPSCR,*
    mov  #$22,SPDR ;
    brclr spte,SPSCR,*
    mov  #$33,SPDR ;
    brclr spte,SPSCR,*
    mov  #$44,SPDR ;
    brclr spte,SPSCR,*
    mov  #$55,SPDR ;
    brclr spte,SPSCR,*
    mov  #$66,SPDR ;
    brclr spte,SPSCR,*

    jsr   Toggle_SS             ; Reset DS1306
    lda  SPSCR
    lda  SPDR

       mov  #$20,SPDR         ; Address of RAM for reading
       brclr spte,SPSCR,*
       jsr  DELAY1
       mov  #$03,SPDR         ; Read config register...dummy write
**************Works OK fullspeed until here.
       brclr spte,SPSCR,*
       jsr  DELAY1
       mov  SPDR,one
    mov  #$03,SPDR         ; Read config register...
    brclr spte,SPSCR,*
    jsr  DELAY1
       mov  SPDR,two

******************************************************************
Toggle_SS:
       bclr     ss,PORTD
       jsr  DELAY1
       bset  ss,PORTD
       lda  SPSCR
       lda  SPDR
       rts
******************************************************************



Re: DS1306 RTC Read with HC08 SPI
I suspect it's that you don't hold SS down long enough for the DS1306 to get
out of write mode. This could be why if works when you single step but not at
full speed. See the DS1306 datasheet to see how long it needs to be held down.


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