AN3371 datasheet(23/45 Pages) STMICROELECTRONICS

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AN3371

Overview of the STM32 advanced RTC

Doc ID 018624 Rev 5

23/45

Figure 15. Tamper with edge detection

Note:

With tamper events, sampling and precharge features are deactivated.

1.8.2

Level detection on tamper input

Setting the tamper filter “TAMPFLT” to a value other than zero means that the tamper input

triggers when a selected level (high or low) is observed on the corresponding TAMPLEVEL

bit.

A tamper detection event is generated when either 2, 4 or 8 (depending on TAMPFLT value)

consecutive samples are observed at the selected level.

MS30113V1

RTC_TAMP1

RTC_TAMPx

STM32

Edge detection

Tamper 1

switch

Tamper x

switch

Table 12.

Tamper features (edge detection)

What to do

How to do it

Comments

Enable Tamper

Set the TAMP1E bit of

RTC_TAFCR register to 1

Select Tamper1 active edge

detection

Select with TAMP1TRG bit

in RTC_TAFCR register

The default edge is rising edge.

Map Tamper1 pin alternate

function

Select with TAMP1INSEL

bit in RTC_TAFCR register

For F2/4 series devices, the Tamper1

pin can be either PI8 or PC13.

Detect a Tamper1event by

interrupt

Set the TAMPIE bit in the

RTC_TAFCR register

An interrupt is generated when a

tamper detection event occurs.

Detect a Tamper1 event by

polling

Poll on the time-stamp flag

(TAMP1F) in the RTC_ISR

To clear the flag, write zero on the

TAMP1F bit.

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