HD404618TF datasheet(53/91 Pages) RENESAS

53 / 91 page

HD404618 Series

Serial Interface

The MCU has a clock-synchronous serial interface which transmits and receives 8-bit data.

The serial interface consists of a serial data register (SR), serial mode register (SMR), port mode register A

(PMRA), octal counter, and multiplexers (see figure 30). The R0

0/SCK pin and the transmit clock are

controlled by writing to the SMR. The transmit clock shifts the contents of the SR, which can be read and

written to by software.

The serial interface is activated by the STS instruction. The octal counter is reset to 000 by this instruction,

starts counting at the falling edge of the transmit clock (

SCK), and it increments at the rising edge of the

clock. A serial interrupt request flag is set when the eighth transmit clock signal is input (the serial

interface is reset) or when serial transmission is discontinued (the octal counter is reset).

Port mode

(PMRA)

SCK

Selector

System

clock

fcyc/fsub

(tcyc/tsubcyc)

Prescaler S (PSS)

I/O

control

logic

Serial mode

(SMR)

Clock

Serial data

Serial interrupt

request flag

(IFS)

1/2

Octal

counter (OC)

I/O

control

logic

Transfer

control

signal

Figure 30 Serial Interface Block Diagram

Serial Mode Register (SMR: $005): Four-bit write-only register that controls the R0

0/SCK pin, prescaler

division ratio, and transmit clock source (table 25 and figure 31). Writing to this register initializes the

serial interface.

HD404618TF Datasheet(PDF) 53 Page - Renesas Technology Corp

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