asp87
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Hi,
I'm trying to interface 18f4550 with 25LC160A (serial ROM) using the PIC's hardware SPI module by polling method. It doesn't work. But it works when I implement SPI in software.
So here I am, trying to figure out how this thing works. Hence wrote codes for 18f4550 master---SPI--- 18f4550 slave communication. That doesn't work either. Below are the codes. Please point out the errors.
The Master will send 0x06 (b'0000 0110') to the slave forever.
The slave will check SSPSTAT, BF bit for '1'. If true, tests SSPBUF against the expected value 0x06. If true, turns ON an LED. Loops forever.
Master
Slave:
I'm trying to interface 18f4550 with 25LC160A (serial ROM) using the PIC's hardware SPI module by polling method. It doesn't work. But it works when I implement SPI in software.
So here I am, trying to figure out how this thing works. Hence wrote codes for 18f4550 master---SPI--- 18f4550 slave communication. That doesn't work either. Below are the codes. Please point out the errors.
The Master will send 0x06 (b'0000 0110') to the slave forever.
The slave will check SSPSTAT, BF bit for '1'. If true, tests SSPBUF against the expected value 0x06. If true, turns ON an LED. Loops forever.
Master
Code:
[SIZE=1] LIST P=18F4550
include "p18f4550.inc"
errorlevel -302, -203, -205, -206
CONFIG FOSC= HS
cblock 0x000
d1
d2
d3
endc
select_ROM macro
bcf PORTD,2
endm
deselect_ROM macro
bsf PORTD, 2
endm
org 0x000
call DelayHalfsec
call DelayHalfsec
call DelayHalfsec
clrf LATA
clrf LATB
clrf LATC
clrf LATD
clrf LATE
movlw 0xFF
movwf ADCON1
movlw 0x00
movwf TRISA
movwf TRISB
movwf TRISC ; RC7 is SDO
movwf TRISE
movlw b'00000000' ;left pic master, RD2 chip select
movwf TRISD
movlw b'00000001' ; RB0 is SDI, RB1 is SCK
movwf TRISB
movlw b'10000000';cke bit 6
movwf SSPSTAT
movlw b'00100010';ckp bit 4
movwf SSPCON1
Send_DT
movlw b'00000110' ;data from Master to Slave
call SPI_Write
call DelayHalfsec
bra Send_DT ; keep sending 0x06 to slave
;--------------------------
SPI_Write
select_ROM ; chip select is not used in this application
movwf SSPBUF ;
Char1 btfss SSPSTAT,BF
bra Char1
movf SSPBUF,W
deselect_ROM
return
;------------------------------------
DelayHalfsec ; 20MHz
movlw 0x15
movwf d1
movlw 0x74
movwf d2
movlw 0x06
movwf d3
DelayHalfsec_0
decfsz d1, f
bra $+4
decfsz d2, f
bra $+4
decfsz d3, f
bra DelayHalfsec_0
bra $+2
bra $+2
return
;----------------
END[/SIZE]Slave:
Code:
LIST P=18F4550
include "p18f4550.inc"
errorlevel -302, -203, -205, -206
CONFIG FOSC= HS
cblock 0x000
temp1
d1
d2
d3
endc
org 0x000
bra slave
slave
call DelayHalfsec
clrf LATA
clrf LATB
clrf LATC
clrf LATD
clrf LATE
movlw 0xFF
movwf ADCON1
movlw 0x00
movwf TRISA
movwf TRISB
movwf TRISC ; RC7 is SDO
movwf TRISE
movlw b'00000100' ;right pic slave, RD2 chip select
movwf TRISD
movlw b'00000001' ; RB0 is SDI, RB1 is SCK
movwf TRISB
movlw b'00000000';cke bit 6
movwf SSPSTAT
movlw b'00100010';ckp bit 4
movwf SSPCON1
Receive_DT
btfss SSPSTAT, BF ; test BUFFER FULL bit
bra Receive_DT ; if not full, wait
movff SSPBUF, temp1
movlw b'00000110' ; this is the value expected from master
xorwf temp1, w
btfsc STATUS, Z
bsf PORTD, 1 ; if expected data matches with actual data, turn ON LED
bra Receive_DT ; else, loop forever
;---------------------------
DelayHalfsec ; 20MHz
movlw 0x15
movwf d1
movlw 0x74
movwf d2
movlw 0x06
movwf d3
DelayHalfsec_0
decfsz d1, f
bra $+4
decfsz d2, f
bra $+4
decfsz d3, f
bra DelayHalfsec_0
bra $+2
bra $+2
return
;----
END