IDT Serial Peripheral Interface
Serial Bit I/O Pins
79RC32438 User Reference Manual
16 - 9
November 4, 2002
Notes
Serial I/O Data Register
Figure 16.9 Serial I/O Data Register (SIOD)
SDI
Description:
Serial Data Input.
When this bit is set to one and the corresponding pin is configured as a bit
I/O port in the SIOFUNC register, the pin is configured as an output. Otherwise, if this bit is reset
and the corresponding pin is configured as a bit I/O port in the SIOFUNC register, the pin is con-
figured as an input. If the pin is not configured as a bit I/O port, the bit in this register has no
effect.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value
SCK
Description:
Serial Clock.
When this bit is set to one and the corresponding pin is configured as a bit I/O port
in the SIOFUNC register, the pin is configured as an output. Otherwise, if this bit is reset and the
corresponding pin is configured as a bit I/O port in the SIOFUNC register, the pin is configured as
an input. If the pin is not configured as a bit I/O port, the bit in this register has no effect.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value
PCI
Description:
PCI Chip Select.
When this bit is set to one and the corresponding pin is configured as a bit
I/O port in the SIOFUNC register, the pin is configured as an output. Otherwise, if this bit is reset
and the corresponding pin is configured as a bit I/O port in the SIOFUNC register, the pin is con-
figured as an input. If the pin is not configured as a bit I/O port, the bit in this register has no
effect.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value
SDO
Description:
Serial Data Output.
Reading this bit returns the state of the SDO pin. Writing a value to this bit
causes the SDO pin to take on the corresponding value if it is configured to be a bit I/O output
port in the SIOFUNC and SIOCFG registers.
Initial Value:
SDO pin value
SIOD
0
31
0
28
SDO
1
SDI
1
SCK
1
PCI
1