M48T86

Clock operations

21/36

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.

Register B MSB

Figure 10.

Update-ended/periodic interrupt relationship

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)

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

BIT0

SET

PIE

AIE

UIE

SQWE

DM

24/12

DSE

AI01652B

UIP

UPDATE PERIOD (1sec)

PF

UF

tPI

tPI

tPI

tBUC

tUC