Hello,
The CCPR1 is defined in a header file as an 8 bit special function register
and not 16 bit special function register. So the compiler does its job
perfectly in this situation.
//==============================================================================
extern __at(0x0FBE) __sfr CCPR1;
extern __at(0x0FBE) __sfr CCPR1L;
extern __at(0x0FBF) __sfr CCPR1H;
The question is, why isn't defined CCPR1 as __sfr16.
I don't know why. Probably the endianness not the same in the hardware as
the SDCC requires. I think, the developers will answer this question.
So you should divide the value moving into two steps temporally while there
will be better solution.
Zsolt
2015-02-16 22:20 GMT+01:00 Tomas Nordin <tom...@kth.se>:
> I am writing code for the PIC 18f2550 target. Forgot to mension.
>
> On Mon, Feb 16, 2015 at 10:16:20PM +0100, Nordin Tomas wrote:
> > Hi
> >
> > I have a function that look like this:
> >
> > void set_ccp1_rc2(unsigned int match_cnt)
> > {
> > T1CONbits.TMR1ON = 0; // Stop timer.
> > TMR1 = 0; //Clear timer.
> > CCPR1 = match_cnt;
> > CCP1CON = 0b00001001; // From here pin will be set. Cleared on
> match.
> > T1CONbits.TMR1ON = 1; // Roll the timer.
> > }
> >
> > It translates after compile to this:
> >
> > S_timing__set_ccp1_rc2 code
> > _set_ccp1_rc2:
> > ; .line 87; SRC/timing.c void set_ccp1_rc2(unsigned int
> match_cnt)
> > MOVFF FSR2L, POSTDEC1
> > MOVFF FSR1L, FSR2L
> > MOVFF r0x00, POSTDEC1
> > MOVFF r0x01, POSTDEC1
> > MOVLW 0x02
> > MOVFF PLUSW2, r0x00
> > MOVLW 0x03
> > MOVFF PLUSW2, r0x01
> > ; .line 89; SRC/timing.c T1CONbits.TMR1ON = 0; // Stop
> timer.
> > BCF _T1CONbits, 0
> > ; .line 90; SRC/timing.c TMR1 = 0; //Clear timer.
> > CLRF _TMR1
> > ; .line 91; SRC/timing.c CCPR1 = match_cnt;
> > MOVF r0x00, W
> > MOVWF _CCPR1
> > ; .line 92; SRC/timing.c CCP1CON = 0b00001001; // From here
> pin will be set. Cleared on match.
> > MOVLW 0x09
> > MOVWF _CCP1CON
> > ; .line 93; SRC/timing.c T1CONbits.TMR1ON = 1; // Roll the
> timer.
> > BSF _T1CONbits, 0
> > MOVFF PREINC1, r0x01
> > MOVFF PREINC1, r0x00
> > MOVFF PREINC1, FSR2L
> > RETURN
> >
> > There is a problem with the running code on the device. It occurs to me
> > that only one byte is written to the _CCPR1 register (MOVWF _CCPR1).
> > Also I am confused to see direct writes to 16-bit equates in the
> > assembly code, is that possible?
> >
> > Should the above translation work as intended or is there something
> > funky?
> >
> > /
> >
> > Tomas
>
>
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