Intel M600 - Manual (Page 74)

PCM-9586 User’s Manual 64
Appendix A Prog. GPIO & W’dog Timer
A.1 Supported GPIO Register
Bellow are detailed description of the GPIO addresses and programming
sample.
A.1.1 GPIO Registers
CRF0 (GP10-GP17 I/O selection register. Default 0xFF)
When set to a '1', respective GPIO port is programmed as an input port.
When set to a '0', respective GPIO port is programmed as an output port.
CRF1 (GP10-GP17 data register. Default 0x00)
If a port is programmed to be an output port, then its respective bit can be
read/written.
If a port is programmed to be an input port, then its respective bit can
only be read.
CRF2 (GP10-GP17 inversion register. Default 0x00)
When set to a '1', the incoming/outgoing port value is inverted.
When set to a '0', the incoming/outgoing port value is the same as in data
register.
Extended Function Index Registers (EFIRs)
The EFIRs are write-only registers with port address 2Eh or 4Eh on PC/
AT systems.
Extended Function Data Registers (EFDRs)
the EFDRs are read/write registers with port address 2Fh or 4Fh on PC/
AT systems.