SH7721 datasheet(630/1524 Pages) RENESAS

630 / 1524 page

Section 17 Realtime Clock (RTC)

Rev. 3.00 Jan. 18, 2008 Page 568 of 1458

REJ09B0033-0300

17.3.6

Date Counter (RDAYCNT)

RDAYCNT is used for setting/counting in the BCD-coded date section. The count operation is

performed by a carry for each day of the hour counter.

Though the range of date which can be set is 01 to 31 (decimal). Errant operation will result if any

other value is set. Carry out write processing after stopping the count operation with the START

bit in RCR2.

RDAYCNT is not initialized by a power-on reset or manual reset, or in standby mode.

The range of date changes with each month and in leap years. Please confirm the correct setting.

Leap years are recognized by dividing the year counter values by 400, 100, and 4 and obtaining a

fractional result of 0. The year counter value of 0000 is included in the leap year.

Bit

Bit Name

Initial Value

R/W

Description

7, 6



All 0

Reserved

These bits are always read as 0. The write value

should always be 0.

5, 4



Undefined

R/W

Counting Ten’s Position of Dates

3 to 0



Undefined

R/W

Counting One’s Position of Dates

Counts on 0 to 9 once per date. When a carry is

generated, 1 is added to the ten’s position.

SH7721 Datasheet(PDF) 630 Page - Renesas Technology Corp