PCF8523 NXP [NXP Semiconductors], PCF8523 Datasheet - Page 19

• Manufacturer Part Number: PCF8523
• Description: Real-Time Clock (RTC) and calendar
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF8523
Product data sheet
8.6.1.1 Oscillator stop flag
8.6.1 Register Seconds
8.6 Time and date registers
Most of these registers are coded in the Binary Coded Decimal (BCD) format. BCD is
used to simplify application use. An example is shown for the array SECONDS in
Table
Table 10.
[1]
Table 11.
The OS flag is set whenever the oscillator is stopped (see
set until cleared by using the interface. When the oscillator is not running, then the OS flag
cannot be cleared. This method can be used to monitor the oscillator.
The oscillator may be stopped, for example, by grounding one of the oscillator pins, OSCI
or OSCO. The oscillator is also considered to be stopped during the time between
power-on and stable crystal resonance. This time may be in a range of 200 ms to 2 s,
depending on crystal type, temperature, and supply voltage. At power-on, the OS flag is
always set.
Bit
7
6 to 4
3 to 0
Seconds value in
decimal
00
01
02
:
09
10
:
58
59
Start-up value.
11.
Symbol
OS
SECONDS
Seconds - seconds and clock integrity status register (address 03h) bit
description
SECONDS coded in BCD format
All information provided in this document is subject to legal disclaimers.
Upper-digit (ten’s place)
Bit
6
0
0
0
:
0
0
:
1
1
Rev. 3 — 30 March 2011
5
0
0
0
:
0
0
:
0
0
Value
0
1
0 to 5
0 to 9
[1]
4
0
0
0
:
0
1
:
1
1
Place value Description
-
-
ten’s place
unit place
Digit (unit place)
Bit
3
0
0
0
:
1
0
:
1
1
Real-Time Clock (RTC) and calendar
clock integrity is guaranteed
clock integrity is not guaranteed;
oscillator has stopped or been
interrupted
actual seconds coded in BCD
format
Figure
2
0
0
0
:
0
0
:
0
0
12). The flag will remain
1
0
0
1
:
0
0
:
0
0
PCF8523
© NXP B.V. 2011. All rights reserved.
0
1
0
1
0
0
1
0
:
:
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