DS1347 Maxim, DS1347 Datasheet - Page 12

• Manufacturer Part Number: DS1347
• Description: The DS1347 SPI-compatible real-time clock (RTC) contains a real-time clock/calendar and 31 x 8 bits of static random-access memory (SRAM)
• Manufacturer: Maxim

Low-Current, SPI-Compatible Real-Time Clock
Interface the device with a microcontroller using a serial,
4-wire, SPI interface. SPI is a synchronous bus for
address and data transfer, and is used with Motorola or
other microcontrollers that have an SPI port. Four con-
nections are required for the interface: DOUT (serial-
data out); DIN (serial-data in); SCLK (serial clock); and
CS (chip select). In an SPI application, the device acts
12
BIT 7
BIT 7
BIT 7
BIT 7
BIT 7
______________________________________________________________________________________
12/
BIT 7
SPI-Compatible Serial Interface
0
0
0
0
0
0
0
0
1
1
BIT 6
BIT 6
BIT 6
BIT 6
BIT 6
BIT 6
1
0
0
0
0
0
0
1
0
0
10 YEAR
10 MINUTES
BIT 5
BIT 5
BIT 5
BIT 5
BIT 5
20 HR
BIT 5
1
1
0
0
0
0
1
1
/PM
10 DATE
10 MO
BIT 4
BIT 4
BIT 4
BIT 4
BIT 4
10 HR
BIT 4
1
1
1
0
0
1
1
as a slave device and the microcontroller acts as the
master. CS is asserted low by the microcontroller to initi-
ate a transfer, and deasserted high to terminate a trans-
fer. DIN transfers input data from the microcontroller to
the device. DOUT transfers output data from the device
to the microcontroller. A shift clock, SCLK, is used to
synchronize data movement between the microcon-
troller and the device. SCLK, which is generated by the
BIT 3
BIT 3
BIT 3
BIT 3
BIT 3
BIT 3
1
1
1
0
0
1
1
BIT 2
BIT 2
BIT 2
BIT 2
BIT 2
BIT 2
Alarm Minutes Register (1Bh)
1
1
1
1
1
1
Alarm Month Register (21h)
Alarm Hours Register (1Dh)
Alarm Year Register (25h)
Alarm Date Register (1Fh)
MINUTES
MONTH
Alarm Day Register (23h)
HOURS
DATE
YEAR
BIT 1
BIT 1
BIT 1
BIT 1
BIT 1
BIT 1
DAY
1
1
1
1
1
1
BIT 0
BIT 0
BIT 0
BIT 0
BIT 0
BIT 0
1
1
1
1
1
1