M41T315W-65MH6TR ST Microelectronics, M41T315W-65MH6TR Datasheet - Page 13

• Manufacturer Part Number: M41T315W-65MH6TR
• Description: Serial Access Phantom RTC Supervisor
• Manufacturer: ST Microelectronics

CLOCK OPERATION
Clock Register Information
Clock information is contained in eight registers of
8 bits, each of which is sequentially accessed 1 bit
at a time after the 64-bit pattern recognition se-
quence has been completed. When updating the
clock registers, each must be handled in groups of
8 bits. Writing and reading individual bits within a
register could produce erroneous results. These
READ/WRITE registers are defined in
5., page
Data contained in the clock registers is in binary
coded decimal format (BCD). Reading and writing
the registers is always accomplished by stepping
though all eight registers, starting with Bit 0 of
Register 0 and ending with Bit 7 of Register 7.
AM-PM/12/24 Mode
Bit 7 of the hours register is defined as the 12-hour
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).
Table 5. RTC Register Map
Keys:
Figure 11. Reset Pulse Waveform
Register
A/P = AM/PM Bit
12/24 = 12 or 24-hour mode Bit
OSC = Oscillator Bit
RST = Reset Bit
0 = Must be set to '0'
0
1
2
3
4
5
6
7
13.
RST
12/24
D7
0
0
0
0
0
D6
0.1 Seconds
0
0
0
0
10 Years
10 Seconds
10 Minutes
OSC
10 /
A/P
D5
0
10 date
RST
10M
Hrs
D4
Table
D3
0
Hours (24 Hour Format)
tRST
Date: Day of the Month
Oscillator and Reset Bits
Bits 4 and 5 of the day register are used to control
the reset and oscillator functions. Bit 4 controls the
reset pin input. When the Reset Bit is set to logic
'1,' the reset input pin is ignored. When the Reset
Bit is set to logic '0,' a low input on the reset pin will
cause the device to abort data transfer without
changing data in the timekeeping registers. Reset
operates independently of all other inputs. Bit 5
controls the oscillator. When set to logic '0,' the os-
cillator turns on and the real time clock/calendar
begins to increment.
Zero Bits
Registers 1, 2, 3, 4, 5, and 6 contain one (1) or
more bits that will always read logic '0.' When writ-
ing to these locations, either a logic '1' or '0' is ac-
ceptable.
0.01 Seconds
D2
Seconds
Minutes
Day of the Week
Month
M41T315Y*, M41T315V, M41T315W
Year
D1
D0
Seconds
Seconds
Minutes
Function/Range
Month
Hours
Date
Year
Day
BCD Format
AI04260
01-12/
00-99
00-59
00-59
00-23
01-31
01-12
00-99
01-7
13/24