PCF2129T datasheet(39/86 Pages) PHILIPS

39 / 86 page

PCF2129

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Product data sheet

Rev. 7 — 19 December 2014

39 of 86

NXP Semiconductors

PCF2129

Accurate RTC with integrated quartz crystal for industrial applications

The following tables show what instruction must be sent to clear the appropriate flag.

[1]

The bits labeled as - have to be rewritten with the previous values.

[1]

The bits labeled as - have to be rewritten with the previous values.

8.11 Timestamp function

The PCF2129 has an active LOW timestamp input pin TS, internally pulled with an

on-chip pull-up resistor to Voper(int). It also has a timestamp detection circuit which can

detect two different events:

1. Input on pin TS is driven to an intermediate level between power supply and ground.

2. Input on pin TS is driven to ground.

The timestamp function is enabled by default after power-on and it can be switched off by

setting the control bit TSOFF (register Timestp_ctl).

Table 54.

Example values in register Control_2

Bit

Control_2

101

10000

Table 55.

Example to clear only AF (bit 4)

Bit

Control_2

0[1]

Table 56.

Example to clear only MSF (bit 7)

Bit

Control_2

0[1]

(1) When using switches or push-buttons, it is recommended to connect a 1 nF capacitance to the TS

pin to ensure proper switching.

Fig 20. Timestamp detection with two push-buttons on the TS pin (for example, for

tamper detection)

PCF2129T Datasheet(PDF) 39 Page - NXP Semiconductors