Emerson PMPPC7448 user manual Real-Time Clock Clock Operation, Address Data Function/Range

Real-Time Clock: Clock Operation

1Seconds register

2Minutes register

3Century/Hours register

4Day register

5Date register

6Month register

7Years register

8Control register

The M41T00 clock continually monitors the supply voltage (Vcc) for an out of tolerance condition. If Vcc falls below switch-over voltage (Vso), the M41T00:

•Terminates an access in progress

•Resets the device address counter

•Does not recognize inputs (prevents erroneous data from being written)

At power-up, the M41T00 uses Vcc at Vso and recognizes inputs.

CLOCK OPERATION

Read the seven Clock registers one byte at a time or in a sequential block. Access the Con- trol register (address location 7) independently. An update to the Clock registers is delayed for 250 ms to allow the read to be completed before the update occurs. This delay does not alter the actual clock time. The eight byte clock register sets the clock and reads the date and time from the clock, as summarized in Table 9-1.

Table 9-1:RTC Register Map

Address:

Data:

Function/Range:

D7

D6

D5

D4

D3

D2

D1

D0

BCD Format

00

ST

10 Seconds

Seconds

Seconds

00—59

01

X

10 Minutes

Minutes

Minutes

00—59

02

CEB

CB

10 Hours

Hours

Century/

0-1/

Hours

00-23

03

X

X

X

X

X

Day

Day

01—07

04

X

X

10 Date

Date

Date

01—31

05

X

X

X

10 M

Month

Month

01—12

06

10 Years

Years

Years

00—99

07

OUT

FT

S

Calibration

Control

—

9-2

PmPPC7448 User’s Manual 10006757-02