Hello all,
I already wrote to Microchip forum but the problem can be in SDCC as well. The
problem is that when I use "built-in SPI" read, I always get 0x00. But with
"manual SPI" I get correct result.
I started to fight with the communication between PIC18f2580 and CC1100 in SDCC
version 2008-Sep-10 ( I compile with sdcc -V -mpic16 -p18f2580 main.c )
I use internal 8MHz oscillator and have configured SPI following way:
CC1100ENB_TRIS = 0; // CC1100 chip select
TRISCbits.TRISC3 = 0; // SCK
TRISCbits.TRISC4 = 1; // SDI
TRISCbits.TRISC5 = 0; // SDO
SSPSTAT = 0x40;
SSPCON1 = 0x22;
Then, for CC1100 register read I use following code:
unsigned char CC1100_read( unsigned char aAdr)
{
unsigned char tmp;
CC1100ENB_PIN = 0;
while ( 1 == PORTCbits.RC4) ; // wait for SO goes low again */
SSPBUF = aAdr; // send address
while ( 0 == SSPSTATbits.BF) ; // wait until end of address transfer
tmp = SSPBUF;
SSPBUF = 0x00; // send dummy data
while ( 0 == SSPSTATbits.BF) ; // wait until end of data transfer
tmp = SSPBUF;
CC1100ENB_PIN = 1;
return SSPBUF;
}
But with this routine I always get 0x00 (and as well as after I send the
address). If I switch off the HW SPI ( SSPCON1 = 0x00) and use software SPI
like following code, everything works OK and I get real register values.
unsigned char CC1100_read_correct( unsigned char aAdr)
{
unsigned char tmp, tmp1, tmp2, i;
tmp2 = aAdr; // address
tmp = 0; // data
CC1100ENB_PIN = 0;
while ( 1 == PORTCbits.RC4) ; // wait for SO goes low again */
PORTCbits.RC3 = 0;
// send address
for( i = 0; i < 8;i++) {
if ( (tmp2&0x80) == 0) {
PORTCbits.RC5 = 0;
} else {
PORTCbits.RC5 = 1;
}
PORTCbits.RC3 = 1;
tmp <<= 1;
if (PORTCbits.RC4 == 1) {
tmp |= 0x01;
}
PORTCbits.RC3 = 0;
}
// send dummy data
for( i = 0; i < 8;i++) {
PORTCbits.RC5 = 0;
PORTCbits.RC3 = 1;
tmp <<= 1;
if (PORTCbits.RC4 == 1) {
tmp |= 0x01;
}
PORTCbits.RC3 = 0;
}
CC1100ENB_PIN = 1;
return SSPBUF;
}
I inspected the generated code from the "HW SPI" routine but it seems to me ok.
But maybe more experienced people find the problem in the code.
_CC1100_read:
; .line 472; main.c unsigned char CC1100_read( unsigned char aAdr)
MOVFF FSR2L, POSTDEC1
MOVFF FSR1L, FSR2L
MOVFF r0x00, POSTDEC1
MOVFF r0x01, POSTDEC1
MOVLW 0x02
MOVFF PLUSW2, r0x00
; .line 479; main.c CC1100ENB_PIN = 0;
BCF _PORTBbits, 5
_00357_DS_:
; .line 480; main.c while ( 1 == PORTCbits.RC4) ; // wait for SO
goes low again */
CLRF r0x01
BTFSC _PORTCbits, 4
INCF r0x01, F
MOVF r0x01, W
XORLW 0x01
BZ _00357_DS_
; .line 518; main.c SSPCON1 = 0x32;
MOVLW 0x32
MOVWF _SSPCON1
; .line 519; main.c SSPBUF = aAdr; // send address
MOVFF r0x00, _SSPBUF
_00360_DS_:
; .line 520; main.c while ( 0 == SSPSTATbits.BF) ; // wait until
end of address transfer
CLRF r0x00
BTFSC _SSPSTATbits, 0
INCF r0x00, F
MOVF r0x00, W
BZ _00360_DS_
_00376_DS_:
_00377_DS_:
; VOLATILE READ - BEGIN
MOVF _SSPBUF, W
; VOLATILE READ - END
; .line 526; main.c SSPBUF = 0x11; // send dummy data
MOVLW 0x11
MOVWF _SSPBUF
_00363_DS_:
; .line 527; main.c while ( 0 == SSPSTATbits.BF) ; // wait until
end of data transfer
CLRF r0x00
BTFSC _SSPSTATbits, 0
INCF r0x00, F
MOVF r0x00, W
BZ _00363_DS_
_00378_DS_:
_00379_DS_:
; VOLATILE READ - BEGIN
MOVF _SSPBUF, W
; VOLATILE READ - END
; .line 534; main.c CC1100ENB_PIN = 1;
BSF _PORTBbits, 5
; .line 536; main.c return SSPBUF;
MOVF _SSPBUF, W
MOVFF PREINC1, r0x01
MOVFF PREINC1, r0x00
MOVFF PREINC1, FSR2L
RETURN
Thank you in advance,
Vaclav
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