Application Note

DS1307 Software Interface

AN1759

9

DS1307 Software Interface

Memory Map

The DS1307’s memory map is shown in Figure 7. The real-time clock

registers are located in address locations $00 to $07. The 56 bytes of

non-volatile RAM are located in address locations $08 to $3F. During

multibyte addresses, the address pointer wraps around to $00 after it

reaches $3F.

Figure 7. DS1307 Memory Map

Register Map

The real-time clock registers are shown in detail in Figure 8. The time

and calendar are set by writing to the appropriate registers. The

information is in binary coded decimal (BCD) format.

To enable the processor, write a 0 to the CLOCK HALT bit in register

$00. The DS1307 is shipped with this bit set to 1.

Either 12-hour or 24-hour clock format can be used. If bit 6 of register

$02 is a 0, the device is in 24-hour mode. Likewise, when bit 6 is a 1, the

device is in 12-hour mode. Bit 5 of address $02 is used for the second

SECONDS

MINUTES

RAM

56X8

HOURS

DAY

DATE

MONTH

YEAR

CONTROL

$00

$07

$08

$3F

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com