VersaLogic VL-EBX-37 Reference Manual page 42

MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
BUSY: MOV
IN
AND
JNZ
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
Writing to a Digital I/O Port Using the SPI Interface
The following code example initiates a write of 55h to Digital I/O port bits DIO15-DIO8.
;Write 44h to configure MCP23S17 register IOCON
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
CALL
EBX-37 Reference Manual
DX, CA8h
AL, 26h ;SPICONTROL: SPI Mode 00, 24bit, auto SPI 6
DX, AL
DX, CA9h
AL, 30h ;SPISTATUS: 8MHz, no IRQ, left-shift
DX, AL
DX, CABh
AL, 44h ;SPIDATA1: Mirror & Open-Drain interrupts
DX, AL
DX, CACh
AL, 0Ah ;SPIDATA2: MCP23S17 address 0x0A
DX, AL
DX, CADh
AL, 40h ;SPIDATA3: MCP23S17 write command
DX, AL
DX, CA9h
AL, DX ;Get SPI status
AL, 01h ;Isolate the BUSY bit
BUSY ;Loop back if SPI transaction is not complete
DX, CA8h
AL, 27h ;SPICONTROL: SPI Mode 00, 24bit, auto SPI 6
DX, AL
DX, CA9h
AL, 30h ;SPISTATUS: 8MHz, no IRQ, left-shift
DX, AL
DX, CABh
AL, 44h ;SPIDATA1: Mirror & Open-Drain interrupts
DX, AL
DX, CACh
AL, 0Ah ;SPIDATA2: MCP23S17 address 0x0A
DX, AL
DX, CADh
AL, 40h ;SPIDATA3: MCP23S17 write command
DX, AL
DX, CA8h
AL, 26h ;SPICONTROL: SPI Mode 00, 24bit,
DX, AL
DX, CA9h
AL, 30h ;SPISTATUS: 8MHz, no IRQ, left-shift
DX, AL
DX, CABh
AL, 44h ;SPIDATA1: mirror and open-drain interrupts
DX, AL
DX, CACh
AL, 0Ah ;SPIDATA2: MCP23S17 IOCON register address 0Ah
DX, AL
DX, CADh
AL, 40h ;SPIDATA3: MCP23S17 write command
DX, AL
BUSY ;Poll busy flag to wait for SPI transaction
Interfaces and Connectors
SPI 6
36