CS5535 datasheet(428/555 Pages) NSC

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Revision 0.8

RTC Register Descriptions (Continued)

5.15.2.12 RTC Control Register B (RTC_CRB)

I/O Address

0Bh

Type

R/W

Reset Value

00h

RTC_CRB Register Map

76543

210

SET_MODE

PI_EN

AI_EN

UEI_EN

RSVD

DATA_MODE

HR_MODE

DAY_SAVE

RTC_CRB Bit Descriptions

Bit

Name

Description

SET_MODE

Set Mode. This bit is reset at VPP power-up reset only.

0: Timing updates occur normally

1: User copy of time is “frozen”, allowing the time registers to be accessed whether or

not an update occurs.

6PI_EN

Periodic Interrupts Enable. Bits [3:0] of RTC_CRA (PIR_SEL) determine the rate at

which this interrupt is generated. It is cleared to 0 on an RTC reset (i.e., hardware

reset) or when the RTC is disable.

0: Disable.

1: Enable.

5AI_EN

Alarm Interrupt Enable. This interrupt is generated immediately after a time update in

which the seconds, minutes, hours, date and month time equal their respective alarm

counterparts. It is cleared to 0 as long as bit 7 of RTC_CRD (VRT bit) reads 0.

0: Disable.

1: Enable.

4UEI_EN

Update Ended Interrupts Enable. This interrupt is generated when an update occurs.

It is cleared to 0 on an RTC reset (i.e., hardware reset) or when the RTC is disabled.

0: Disable.

1: Enable.

RSVD

Reserved. This bit is defined as “Square Wave Enable” by the MC146818 and is not

supported by the RTC. This bit is always read as 0.

2DATA_MODE

Data Mode. Selects data mode. This bit is reset at VPP power-up reset only.

0: BCD format.

1: Binary format.

HR_MODE

Hour Mode. Selects hour mode. This bit is reset at VPP power-up reset only.

0: 12-hour format.

1: 24-hour format.

0DAY_SAVE

Daylight Saving. Enables/disables daylight savings mode. This bit is reset at VPP

power-up reset only.

0: Disable.

1: Enable.

In the spring, time advances from 1:59:59 AM to 3:00:00 AM on the first Sunday in

April.

In the fall, time returns from 1:59:59 AM to 1:00:00 AM on the last Sunday in October.

CS5535 Datasheet(PDF) 428 Page - National Semiconductor (TI)

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