SH7721 datasheet(637/1524 Pages) RENESAS

637 / 1524 page

Section 17 Realtime Clock (RTC)

Rev. 3.00 Jan. 18, 2008 Page 575 of 1458

REJ09B0033-0300

17.3.16

RTC Control Register 1 (RCR1)

RCR1 is a register that affects carry flags and alarm flags. It also selects whether to generate

interrupts for each flag.

RCR1 is initialized to H'00 by a power-on reset or a manual reset, all bits are initialized to 0

except for the CF flag, which is undefined. When using the CF flag, it must be initialized

beforehand. This register is not initialized in standby mode.

Bit

Bit Name

Initial Value

R/W

Description

Undefined

R/W

Carry Flag

Status flag that indicates that a carry has

occurred. CF is set to 1 when a count-up to 64-

Hz occurs at the second counter carry or 64-Hz

counter read. A count register value read at this

time cannot be guaranteed; another read is

required.

0: No carry of 64-Hz counter by second counter

or 64-Hz counter

[Clearing condition]

When 0 is written to CF

1: Carry of 64-Hz counter by second counter or

64 Hz counter

[Setting condition]

When the second counter or 64-Hz counter is

read during a carry occurrence by the 64-Hz

counter, or 1 is written to CF.

6, 5

—

All 0

Reserved

These bits are always read as 0. The write value

should always be 0.

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