STM8AF528A datasheet(21/110 Pages) STMICROELECTRONICS

21 / 110 page

STM8AF52/62xx, STM8AF51/61xx

Product overview

Doc ID 14395 Rev 9

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5.7

Timers

5.7.1

Watchdog timers

The watchdog system is based on two independent timers providing maximum security to

the applications. The watchdog timer activity is controlled by the application program or

option bytes. Once the watchdog is activated, it cannot be disabled by the user program

without going through reset.

Window watchdog timer

The window watchdog is used to detect the occurrence of a software fault, usually

generated by external interferences or by unexpected logical conditions, which cause the

application program to abandon its normal sequence.

The window function can be used to trim the watchdog behavior to match the application

timing perfectly. The application software must refresh the counter before time-out and

during a limited time window. If the counter is refreshed outside this time window, a reset is

issued.

Independent watchdog timer

The independent watchdog peripheral can be used to resolve malfunctions due to hardware

or software failures.

It is clocked by the 128 kHz LSI internal RC clock source, and thus stays active even in case

of a CPU clock failure. If the hardware watchdog feature is enabled through the device

option bits, the watchdog is automatically enabled at power-on, and generates a reset

unless the key register is written by software before the counter reaches the end of count.

5.7.2

Auto-wakeup counter

This counter is used to cyclically wakeup the device in Active-halt mode. It can be clocked by

the internal 128 kHz internal low-frequency RC oscillator or external clock.

LSI clock can be internally connected to TIM3 input capture channel 1 for calibration.

5.7.3

Beeper

This function generates a rectangular signal in the range of 1, 2 or 4 kHz which can be

output on a pin. This is useful when audible sounds without interference need to be

generated for use in the application.

5.7.4

Advanced control and general purpose timers

STM8A devices described in this datasheet, contain up to three 16-bit advanced control and

general purpose timers providing nine CAPCOM channels in total. A CAPCOM channel can

be used either as input compare, output compare or PWM channel. These timers are

named TIM1, TIM2 and TIM3.

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