SH7708 datasheet(447/633 Pages) RENESAS

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15.2.3

Serial Port Register (SCSPTR)

The serial port register (SCSPTR) is an 8-bit register that the CPU can always read and write. It

controls I/O and data of the port multiplexed with the serial communication interface (SCI) pins.

Input data can be read from the RxD pin and output data can be transmitted to the TxD pin; this

controls breaks for serial transmission and reception. In addition, SCK pin data reading and output

data writing can be performed by means of bits 3 and 2.

All SCSPTR bits except bits 2 and 0 are initialized to 0 by a power-on reset; the value of bits 2

and 0 is undefined. SCSPTR is not initialized by a manual reset or in standby mode, and it retains

its contents.

Bit:

Bit name:

—

SPB1IO SPB1DT SPB0IO SPB0DT

Initial value:

—

R/W:

R/W

Bits 7 to 4—Reserved: These bits always read 0. The write value should always be 0.

Bit 3—Serial Port Clock Port I/O (SPB1IO): Specifies serial port SCK pin input/output. When the

SCK pin is actually set as a port output pin and outputs the value set by the SPB1DT bit, the C/

bit in SCSMR and the CKE1 and CKE0 bits in SCSCR should be cleared to 0.

Bit 3: SPB1IO

Description

The SPB1DT value is not output to the SCK pin.

(Initial value)

The SPB1DT bit value is output to the SCK pin.

Bit 2—Serial Port Clock Port Data (SPB1DT): Specifies the serial port SCK pin input/output data.

Input or output is specified by the SPB1IO bit (see the description of SPB1IO for details). When

output is specified, the value of the SPB1DT bit is output to the SCK pin. The SCK pin value is

read from the SPB1DT bit regardless of the value of the SPB1IO bit. The initial value of this bit

after a power-on reset is undefined.

Bit 2: SPB1DT

Description

I/O data level is low.

(Initial value)

I/O data level is high.

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