M48T86PC1(2007) View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M48T86PC1
(Rev.:2007)

5.0 V PC real-time clock

STMicroelectronics 

M48T86

Clock operations

24/12

The 24/12 Control Bit establishes the format of the hours byte. A '1' indicates the 24-hour

mode and a '0' indicates the 12-hour mode. This bit is READ/WRITE and is not affected by

internal functions or RST.

DSE: daylight savings enable

The Daylight Savings Enable (DSE) Bit is a READ/WRITE bit which enables two special

updates when set to a '1.' On the first Sunday in April, the time increments from 1:59:59AM

to 3:00:00 AM. On the last Sunday in October, when the time reaches 1:59:59 AM, it

changes to 1:00:00 AM. These special updates do not occur when the DSE Bit is a '0.' This

bit is not affected by internal functions or RST.

Table 6.

BIT7

SET

Register B MSB

BIT6

BIT5

PIE

AIE

BIT4

UIE

BIT3

SQWE

BIT2

DM

BIT1

24/12

BIT0

DSE

Figure 10. Update-ended/periodic interrupt relationship

UPDATE PERIOD (1sec)

UIP

tPI

tPI

tPI

PF

tBUC

tUC

UF

AI01652B

Register C

IRQF: interrupt request flag

The Interrupt Request Flag (IRQF) Bit is set to a '1' when one or more of the following are

true:

PF = PIE = 1

AF = AIE = 1

UF = UIE = 1

(e.g., IRQF = PF*PIE+AF*AIE+UF*UIE)

21/36

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