Datasheet
PIC18F47J13 FAMILY
DS39974A-page 308 Preliminary 2010 Microchip Technology Inc.
EXAMPLE 20-2: 512-BYTE SPI MASTER MODE Init AND TRANSFER
;For this example, let's use RP5(RB2) for SCK2,
;RP4(RB1) for SDO2, and RP3(RB0) for SDI2
;Let’s use SPI master mode, CKE = 0, CKP = 0,
;without using slave select signalling.
InitSPIPins:
movlb 0x0F ;Select bank 15, for access to ODCON3 register
bcf ODCON3, SPI2OD ;Let’s not use open drain outputs in this example
bcf LATB, RB2 ;Initialize our (to be) SCK2 pin low (idle).
bcf LATB, RB1 ;Initialize our (to be) SDO2 pin to an idle state
bcf TRISB, RB1 ;Make SDO2 output, and drive low
bcf TRISB, RB2 ;Make SCK2 output, and drive low (idle state)
bsf TRISB, RB0 ;SDI2 is an input, make sure it is tri-stated
;Now we should unlock the PPS registers, so we can
;assign the MSSP2 functions to our desired I/O pins.
movlb 0x0E ;Select bank 14 for access to PPS registers
bcf INTCON, GIE ;I/O Pin unlock sequence will not work if CPU
;services an interrupt during the sequence
movlw 0x55 ;Unlock sequence consists of writing 0x55
movwf EECON2 ;and 0xAA to the EECON2 register.
movlw 0xAA
movwf EECON2
bcf PPSCON, IOLOCK ;We may now write to RPINRx and RPORx registers
bsf INTCON, GIE ;May now turn back on interrupts if desired
movlw 0x03 ;RP3 will be SDI2
movwf RPINR21 ;Assign the SDI2 function to pin RP3
movlw 0x0A ;Let’s assign SCK2 output to pin RP4
movwf RPOR4 ;RPOR4 maps output signals to RP4 pin
movlw 0x04 ;SCK2 also needs to be configured as an input on the
same pin
movwf RPINR22 ;SCK2 input function taken from RP4 pin
movlw 0x09 ;0x09 is SDO2 output
movwf RPOR5 ;Assign SDO2 output signal to the RP5 (RB2) pin
movlb 0x0F ;Done with PPS registers, bank 15 has other SFRs
InitMSSP2:
clrf SSP2STAT ;CKE = 0, SMP = 0 (sampled at middle of bit)
movlw b'00000000' ;CKP = 0, SPI Master mode, Fosc/4
movwf SSP2CON1 ;MSSP2 initialized
bsf SSP2CON1, SSPEN ;Enable the MSSP2 module
InitSPIDMA:
movlw b'00111010' ;Full duplex, RX/TXINC enabled, no SSCON
movwf DMACON1 ;DLYINTEN is set, so DLYCYC3:DLYCYC0 = 1111
movlw b'11110000' ;Minimum delay between bytes, interrupt
movwf DMACON2 ;only once when the transaction is complete