8-Bit Serial I/O Pins - Fujitsu F2MC-8L Series Hardware Manual

8.3

8-bit Serial I/O Pins

This section describes the pins and pin block diagram of 8-bit serial I/O.
8-bit Serial I/O Pins
8-bit serial I/O uses the P32/SI, P31/SO, and P30/SCK pins.
P32/SI pin
The P32/SI pin can function either as a general-purpose I/O port (P32) or as the serial data
input pin (hysteresis input) for 8-bit serial I/O (SI).
SI: Set the P32/SI pin as an input port in the port data direction register (DDR3: bit 2 =
"2") when using as the SI pin.
P31/SO pin
The P31/SO pin can function either as a general-purpose I/O port (P31) or as the serial data
output pin (CMOS output) for 8-bit serial I/O (SO).
Enabling serial data output (SMR: SOE = "1") automatically sets the P31/SO pin as an output
pin, regardless of the port data direction register (DDR3: bit 1) value, and sets the pin to function
as the SO pin.
P30/SCK pin
The P30/SCK pin can function either as a general-purpose I/O port (P30) or as the shift clock
I/O pin (hysteresis input, CMOS output) for 8-bit serial I/O (SCK).
• When using as the shift clock input pin
When using SCK as an input pin, set the pin as an input port in the port data direction
register (DDR3: bit 0 = "0") and disable shift clock output (SMR: SCKE = "0"). In this
case, always select external shift clock operation (SMR: CKS1, CKS0 = "11
• When using as the shift clock output pin
Enabling shift clock output (SMR: SCKE = "1") automatically sets the P30/SCK pin as
an output pin, regardless of the port data direction register (DDR3: bit 0) value, and
sets the pin to function as the SCK output pin. In this case, always select internal shift
clock operation (SMR: CKS1, CKS0 = other than "11
8.3 8-bit Serial I/O Pins
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