Mitsubishi DS907x SIP, DS5000TK manual DS1215 Time Registers Description ±4, Special Bits, 148

USER'S GUIDE

DS1215 TIME REGISTERS DESCRIPTION Figure 17±4

CLOCK									RANGE (BCD)
REGISTER #	7	6	5	4	3	2	1	0

0		0.1 SEC	0.01 SEC	00±99
1	0	10's OF SECONDS	SECONDS	00±59

2 0 10's OF MINUTES MINUTES 00±59

3	12/24	0	10	A/P	HR	HOUR	01±12
							00±23

4 0 0 OSC 0 0 DAY 01±07

5 0 0 10 DATE DATE 01±31

6	0	0	0	10	MONTH	01±12
				MON

7 10 YEAR YEAR 00±99

REGISTERS

The time information is contained in eight registers that are each 8 bits long. After the 64±bit recognition pattern has been received, data in these registers is accessed one bit at a time which is shown conceptually in Figure 17±4. It is recommended that data written to the RTC be handled in groups of 8 bits corresponding to the register bytes in order to prevent erroneous results.

Register data is always in BCD format except for the hours register (register 3), whose format changes de- pending upon the state of bit 7. If bit 7 is high, the 12±hour mode is selected and bit 5 of the hours register becomes an AM/PM indicator; if bit 7 is low, the 24±hour mode is selected and bit 5 becomes the second 10±hour bit (20±23 hours). Figure 17±5 contains exam-

ples that illustrate the content of these registers for dif- ferent modes and times.

SPECIAL BITS

Bit 5 of the days register (register 4) is the control bit for the clock micropower oscillator. Clearing bit 5 to a logic 0 enables the oscillator for normal operation; setting bit 5 to a logic 1 disables the oscillator and halts the time- keeping. It is recommended that bit 5 always be cleared to 0.

Register locations shown as logic 0's in Figure 17±4 will always return a 0 when being read. Write operations to these bit locations are ignored by the clock and have no effect on its operation.

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