Rainbow-electronics DS1375 Manual de usuario descargar pdf (Pagina 6)

to location 00h, the current time is transferred to a sec-

ond set of registers. The time information is read from

these secondary registers, while the clock may contin-

ue to run. This eliminates the need to reread the regis-

ters in case the main registers update during a read.

Note: Unless otherwise specified, the state of the regis-

ters is not defined when power is first applied.

Clock and Calendar

The time and calendar information is obtained by read-

ing the appropriate register bytes. Table 1 shows the

RTC registers. The time and calendar data are set or

initialized by writing the appropriate register bytes. The

contents of the time and calendar registers are in the

binary-coded decimal (BCD) format. The DS1375 can

be run in either 12-hour or 24-hour mode. Bit 6 of the

hours register is defined as the 12- or 24-hour mode

select bit. When high, the 12-hour mode is selected. In

the 12-hour mode, bit 5 is the AM/PM bit with logic high

being PM. In the 24-hour mode, bit 5 is the second 10-

hour bit (20–23 hours). The century bit (bit 7 of the

month register) is toggled when the years register over-

flows from 99 to 00.

The day-of-week register increments at midnight.

Values that correspond to the day of week are user-

defined but must be sequential (i.e., if 1 equals

Sunday, then 2 equals Monday, and so on). Illogical

time and date entries result in undefined operation.

When reading or writing the time and date registers,

secondary (user) buffers are used to prevent errors

when the internal registers update. When reading the

time and date registers, the user buffers are synchro-

nized to the internal registers on any START or STOP

and when the register pointer rolls over to zero. The

time information is read from these secondary registers,

while the clock continues to run. This eliminates the

need to reread the registers in case the main registers

update during a read.

DS1375

2-Wire Digital Input RTC with Alarm

6 _____________________________________________________________________

Table 1. Timekeeping Registers and SRAM

ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 FUNCTION RANGE

00h 0 10 Seconds Seconds Seconds 00–59

01h 0 10 Minutes Minutes Minutes 00–59

AM/PM

02h 0 12/24

10 Hours

10 Hours Hours Hours

1–12 + AM/PM

00–23

03h 0 0 0 0 0 Day Day 1–7

04h 0 0 10 Date Date Date 00–31

05h Century 0 0

Month

Months

Month/

Century

01–12 +

Century

06h 10 Year Year Year 00–99

07h A1M1 10 Seconds Seconds Alarm 1 Seconds 00–59

08h A1M2 10 Minutes Minutes Alarm 1 Minutes 00–59

AM/PM

09h A1M3 12/24

10 Hours

10 Hours Hours Alarm 1 Hours

1–12 + AM/PM

00–23

Day Alarm 1 Day 1–7

0Ah A1M4 DY/DT

10 Date Date Alarm 1 Date 1–31

0Bh A2M2 10 Minutes Minutes Alarm 2 Minutes 00–59

AM/PM

0Ch A2M3 12/24

10 Hours

10 Hours Hours Alarm 2 Hours

1–12 + AM/PM

00–23

— Day Alarm 2 Day 1–7

0Dh A2M4 DY/DT

10 Date Date Alarm 2 Date 1–31

0Eh ECLK CLKSEL1 CLKSEL0 RS2 RS1 INTCN A2IE A1IE Control —

0Fh 0 0 0 0 0 0 A2F A1F

Control/

Status

—

10h–1Fh B7 B6 B5 B4 B3 B2 B1 B0 SRAM 00–FFH

1 2 3 4 5 6 7 8 9 10 11

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