PCA2125 Datasheet, PDF (15/40 Pages) NXP Semiconductors – SPI Real time clock / calendar

NXP Semiconductors
PCA2125
SPI Real time clock / calendar
6.6 Timer functions
The countdown timer has four selectable source clocks allowing for countdown periods in
the range from less than 1ms to more than 4hours. There are also two pre-defined timers
which can be used to generate an interrupt once per second or once per minute.
Address registers 01_HEX, 0E_HEX and 0F_HEX are used to control the timer function and
output.
Table 25. Control 2 (address 01_HEX) bits description
Bit
Symbol Value
Description
7
MI
0
Minute interrupt is disabled
1
Minute interrupt is enabled
6
SI
0
Second interrupt is disabled
1
Second interrupt is enabled
5
MSF
0
No minute or second interrupt generated
1
Flag set when minute or second interrupt generated. Flag
must be cleared to release INT.
4
TI/TP
0
Interrupt pin follows timer flags
1
Interrupt pin generates a pulse
2
TF
0
No countdown timer interrupt generated
1
Flag set when countdown timer interrupt generated. Flag must
be cleared to release INT.
0
TIE
0
No interrupt generated from the countdown timer flag
1
Interrupt generated when countdown timer flag set
3
AF
See Table 8.
1
AIE
See Table 8.
Table 26. Timer control (address 0E_HEX) bits description
Bit
Symbol Value
Description
6:2
0
Reserved for future use.
7
TE
0
Countdown timer is disabled
1
Countdown timer is enabled
1 to 0 CDT
00
4096 Hz countdown timer source clock
01
64 Hz countdown timer source clock
10
1 Hz countdown timer source clock
11
1⁄60 Hz countdown timer source clock
Section
Section 6.6.2
Table 27. Countdown timer (address 0A_HEX) bits description
Bit
Symbol Value
Description
Section
7 to 0 n
00 to FF
countdown value = n;
Section 6.6.2
CountdownPeriod = -------------------------------ⁿ-------------------------------
SourceClockFrequency
PCA2125_00
Preliminary data sheet
Rev. 00.11 — 30 January 2007
© NXP B.V. 2007. All rights reserved.
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