pca2125 NXP Semiconductors, pca2125 Datasheet - Page 16

• Manufacturer Part Number: pca2125
• Description: Spi Real Time Clock / Calendar Semiconductors
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA2125_00
Preliminary data sheet
6.6.1 Second and minute interrupt; SI, MI
The minute and second interrupt are pre-defined timers for generating periodic interrupts.
The timers can be enabled independently from one another, however a minute interrupt
enabled on top of a second interrupt will not be distinguishable since it will occur at the
same time; see
Table 28.
The minute/second flag, MSF, is set to ‘1’ when either the seconds or the minutes counter
increments according to the currently enabled interrupt. The flag can be read and cleared
by the interface. The status of the MSF does not affect INT pulse generation. If the MSF
flag is not cleared prior to the next coming interrupt period, an INT pulse will still be
generated.
The purpose of the flag is to allow the controlling system to interrogate the PCA2125 and
identify the source of the interrupt i.e. minute/second or countdown timer.
Table 29:
Minute interrupt, MI
disabled
enabled
disabled
enabled
Minute interrupt, MI
disabled
enabled
disabled
enabled
Fig 10. INT example for SI and MI
MSF when only MI enabled
INT when only MI enabled
MSF when SI enabled
In this example, TI/TP is set to 1 resulting in
not cleared after an interrupt.
INT when SI enabled
Effect of MI and SI on INT generation
Effect of MI and SI on MSF
seconds counter
minutes counter
Figure
Rev. 00.11 — 30 January 2007
10.
Second interrupt, SI
disabled
disabled
enabled
enabled
Second interrupt, SI
disabled
disabled
enabled
enabled
58
59
1
/
64
59
11
Hz wide interrupt pulse and the MSF flag is
Result
No interrupt generated
An interrupt once per minute
An interrupt once per second
An interrupt once per second
Result
MSF never set.
MSF set when minutes counter increments
MSF set when seconds counter increments
MSF set when seconds counter increments
00
12
SPI Real time clock / calendar
00
PCA2125
© NXP B.V. 2007. All rights reserved.
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