VersaLogic EBX-22 Reference Manual page 63

AND AL, 01h
JNZ BUSY
MOV DX, 1D8h
MOV AL, 27h
OUT DX, AL
MOV DX, 1D9h
MOV AL, 30h
OUT DX, AL
MOV DX, 1DBh
MOV AL, 44h
OUT DX, AL
MOV DX, 1DCh
MOV AL, 0Ah
OUT DX, AL
MOV DX, 1DDh
MOV AL, 40h
OUT DX, AL
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
;Configure MCP23S17 register IODIRA for outputs
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
OUT
CALL
;Write 55h to MCP23S17 register GPIOA
MOV
MOV
OUT
MOV
MOV
OUT
MOV
MOV
EBX-22 Reference Manual
;Isolate the BUSY bit
;Loop back if SPI transaction is not complete
;SPICONTROL: SPI Mode 00, 24bit, auto DIO_1_SS#
;SPISTATUS: 8MHz, no IRQ, left-shift
;SPIDATA1: Mirror & Open-Drain interrupts
;SPIDATA2: MCP23S17 address 0x0A
;SPIDATA3: MCP23S17 write command
DX, 1D8h
AL, 26h ;SPICONTROL: SPI Mode 00, 24bit, DIO_0_SS#
DX, AL
DX, 1D9h
AL, 30h ;SPISTATUS: 8MHz, no IRQ, left-shift
DX, AL
DX, 1DBh
AL, 44h ;SPIDATA1: mirror and open-drain interrupts
DX, AL
DX, 1DCh
AL, 0Ah ;SPIDATA2: MCP23S17 IOCON register address 0Ah
DX, AL
DX, 1DDh
AL, 40h ;SPIDATA3: MCP23S17 write command
DX, AL
BUSY ;Poll busy flag to wait for SPI transaction
DX, 1DBh
AL, 00h ;SPIDATA1: 00h for outputs
DX, AL
DX, 1DCh
AL, 00h ;SPIDATA2: MCP23S17 register address 00h
DX, AL
DX, 1DDh
AL, 40h ;SPIDATA3: MCP23S17 write command
DX, AL
BUSY ;Poll busy flag to wait for SPI transaction
DX, 1DBh
AL, 55h ;SPIDATA1: data to write
DX, AL
DX, 1DCh
AL, 14h ;SPIDATA2: MCP23S17 register address 14h
DX, AL
DX, 1DDh
AL, 40h ;SPIDATA3: MCP23S17 write command
Interfaces and Connectors
57