PCF2123_09 Datasheet, PDF (10/55 Pages) NXP Semiconductors – SPI Real time clock/calendar

NXP Semiconductors
PCF2123
SPI Real time clock/calendar
9.3.2 Register Control_2
Table 6. Control_2 - control and status register 2 (address 01h) bits description
Bit Symbol
Value
Description
Reference
7
MI
0^[1]
minute interrupt is disabled
Section 9.8.3
1
minute interrupt is enabled
6
SI
0^[1]
second interrupt is disabled
1
second interrupt is enabled
5
MSF
0^[1]
no minute or second interrupt generated
1
flag set when minute or second interrupt
generated;
flag must be cleared to clear interrupt
when TI_IP = 0
4
TI_TP
0^[1]
interrupt pin follows timer flags
Section 9.9.2
1
interrupt pin generates a pulse
3
AF
0^[1]
no alarm interrupt generated
Section 9.7.5
1
flag set when alarm triggered;
flag must be cleared to clear interrupt
2
TF
0^[1]
no countdown timer interrupt generated Section 9.8.4
1
flag set when countdown timer interrupt
generated;
flag must be cleared to clear interrupt
when TI_IP = 0
1
AIE
0^[1]
no interrupt generated from the alarm flag Section 9.9.3
1
interrupt generated when alarm flag set
0
TIE
0^[1]
no interrupt generated from the countdown Section 9.9.2
timer
1
interrupt generated by the countdown timer
[1] Default value.
9.4 OS flag
The PCF2123 includes a flag (OS in register Seconds, see Table 8) which is set whenever
the oscillator is stopped (see Figure 8 and Figure 9). The flag will remain set until cleared
by software. If the flag cannot be cleared, then the PCF2123 oscillator is not running. This
method can be used to monitor the oscillator and to determine if the supply voltage has
reduced to the point where oscillation fails.
PCF2123_2
Product data sheet
Rev. 02 — 4 December 2009
© NXP B.V. 2009. All rights reserved.
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