HD404369F datasheet(82/117 Pages) RENESAS

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HD404369 Series

Serial Mode Register (SMR: $005): This register has the following functions (figure 62).

• R0

0/SCK pin function selection

• Transmit clock selection

• Prescaler division ratio selection

• Serial interface initialization

Serial mode register (SMR: $005) is a 4-bit write-only register. It is reset to $0 by MCU reset.

A write signal input to serial mode register (SMR: $005) discontinues the input of the transmit clock to the

serial data register and octal counter, and the octal counter is reset to 000. Therefore, if a write is performed

during data transfer, the serial interrupt request flag (IFS: $003, bit 2) is set.

Written data is valid from the second instruction execution cycle after the write operation, so the STS

instruction must be executed at least two cycles after that.

Bit

Initial value

Read/Write

Bit name

SMR3

SMR2

SMR0

SMR1

Serial mode register (SMR: $005)

SMR2

SMR0

SMR1

SMR3

R00/SCK

Mode Selection

R00

SCK

Output

Input

Clock Source

External clock

—

Prescaler

Division Ratio

Refer to

table 28

Prescaler

System clock

Figure 62 Serial Mode Register (SMR)

HD404369F データシート(PDF) 82 Page - Renesas Technology Corp

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