A300 Motherboard
Bit 4 00h 00h
Bit 5 00h 00h
Bit 6 00h 00h
Bit 7 00h 00h
B.2 Assembly Language Samples B.2.1 GPIO Initialization Procedure
The following instruction set initializes one pin on the GPIO connector.
MOV DX, 320h
Moves 320h into the DX data register for one of the GPIO
pins
MOV AL, XXh
Moves the user defined output value XXh into the low bit
accumulator register AL
OUT DX, AL
The content of the low bit accumulator register AL is
transmitted to the address stored in the DX data register
The following instruction set initializes the input/output setting register for one pin on the
GPIO connector to specify whether that pin inputs or outputs data.
MOV DX, 321h
Moves 320h into the DX data register for one of the GPIO
pins
MOV AL, YYh
Moves the user defined output value YYh into the low bit
accumulator register AL. If YY is specified as 0, the pin is
an output pin. If YY is specified as 1, the pin is an input
pin.
OUT DX, AL
The content of the low bit accumulator register AL is
transmitted to the address stored in the DX data register
B.2.2 General Purpose Output Procedure
The following instruction set is for a GPO procedure for one pin on the GPIO connector.