M41T00CAPPC1 データシートの表示（PDF） - STMicroelectronics
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M41T00CAPPC1
STMicroelectronics
M41T00CAPPC1 Datasheet PDF : 27 Pages
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Clock operation
4
Clock operation
M41T00CAP
The 8-byte register map (see Table 2) is used to both set the clock and to read the date and
time from the clock, in a binary coded decimal format. Seconds, minutes, and hours are
contained within the first three registers. Bits D6 and D7 of clock register 02h (century/hours
register) contain the century enable bit (CEB) and the century bit (CB). Setting CEB to a '1'
will cause CB to toggle, either from '0' to '1' or from '1' to '0' at the turn of the century
(depending upon its initial state). If CEB is set to a '0,' CB will not toggle. Bits D0 through D2
of Register 03h contain the Day (day of week). Registers 04h, 05h, and 06h contain the date
(day of month), month and years. The eighth clock register is the calibration register (this is
described in the clock calibration section). Bit D7 of register 00h contains the STOP bit (ST).
Setting this bit to a '1' will cause the oscillator to stop. If the device is expected to spend a
significant amount of time on the shelf, the oscillator may be stopped to reduce current
drain. When reset to a '0' the oscillator restarts within one second. The seven clock registers
may be read one byte at a time, or in a sequential block. The calibration register (address
location 07h) may be accessed independently. Provision has been made to ensure that a
clock update does not occur while any of the seven clock addresses are being read. If a
clock address is being read, an update of the clock registers will be halted. This will prevent
a transition of data during the READ.
Table 2. TIMEKEEPER® register map
Addr
D7 D6 D5 D4 D3 D2 D1 D0
00h ST
10 seconds
Seconds
01h OF
10 minutes
Minutes
02h CEB CB 10 hours
Hours (24-hour format)
03h 0
0
0
0
0
Day of week
04h 0
0
10 date
Date: day of month
05h 0
0
0 10M
Month
06h
10 years
Year
07h OUT FT S
Calibration
Function/range BCD format
Seconds
Minutes
Century/hours
Day
Date
Month
Year
Calibration
00-59
00-59
0-1/00-23
01-7
01-31
01-12
00-99
Keys:
0 = must be set to '0'
CB = century bit
CEB = century enable bit
FT = frequency test bit
OF = oscillator fail bit
OUT = output level
S = sign bit
ST = stop bit
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Doc ID 14557 Rev 5
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