PCF8563 查看數據表（PDF） - Philips Electronics
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PCF8563 Datasheet PDF : 30 Pages
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Philips Semiconductors
PCF8563
Real-time clock/calendar
8.6.6 CLKOUT frequency register
Table 23: CLKOUT frequency register bits description (address 0DH)
Bit
Symbol Description
7
FE
FE = 0; the CLKOUT output is inhibited and the CLKOUT output is
set to high-impedance. FE = 1; the CLKOUT output is activated.
6 to 2
−
not implemented
1
FD1
These bits control the frequency output (fCLKOUT) on the CLKOUT
0
FD0
pin; see Table 24.
Table 24: CLKOUT frequency selection
FD1
0
FD0
0
fCLKOUT
32.768 kHz
0
1
1 024 Hz
1
0
32 Hz
1
1
1 Hz
8.6.7 Countdown timer registers
The Timer register is an 8-bit binary countdown timer. It is enabled and disabled via
the Timer control register bit TE. The source clock for the timer is also selected by the
Timer control register. Other timer properties, e.g. interrupt generation, are controlled
via the Control/status 2 register. For accurate read back of the countdown value, the
I2C-bus clock SCL must be operating at a frequency of at least twice the selected
timer clock.
Table 25: Timer control register bits description (address 0EH)
Bit
Symbol Description
7
TE
TE = 0; timer is disabled. TE = 1; timer is enabled.
6 to 2
−
not implemented
1
TD1
Timer source clock frequency selection bits. These bits determine
0
TD0
the source clock for the countdown timer, see Table 26. When not
in use, TD1 and TD0 should be set to ‘11’ (1⁄60 Hz) for power
saving.
Table 26: Timer source clock frequency selection
TD1
TD0
Timer source clock frequency (Hz)
0
0
4 096
0
1
64
1
0
1
1
1
1⁄60
Table 27: Timer countdown value register bits description (address 0FH)
Bit
Symbol
Description
7 to 0
<timer countdown value> This register holds the loaded countdown value ‘n’.
Countdown period = S----o---u---r--c---e----c--l--o---c--n-k------f--r--e--q---u----e--n---c---y-
9397 750 04855
Product specification
16 April 1999
© Philips Electronics N.V. 1999. All rights reserved.
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