Peripheral firmware examples description

AN4157

16/24

Doc ID 023629 Rev 1

The associated firmware performs the following operations:

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It configures the Tamper pin to be falling edge, and enables the Tamper interrupt.

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It writes the data to all RTC Backup data registers, then check whether the data were

correctly written. If yes, LED3 turns on, otherwise LED4 turns on.

●

It applies a low level on the TAMPER2 pin (PA00) by pressing TAMPER push button,

the RTC backup data registers are reset and the Tamper interrupt is generated.

The corresponding ISR then checks if the RTC Backup data registers are cleared. If so,

LED5 is switched ON, otherwise LED6 is switched ON.

3.18

SysTick timer example

3.18.1

Purpose

This example shows how to configure the SysTick timer and use it to generate a 1 ms time

base.

3.18.2

Description

In this example:

●

The SysTick timer is initialized.

●

The SysTick timer interrupt is enabled in the NVIC.

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The SysTick timer/counter starts in free running mode to generate periodical interrupts.

●

The SysTick timer interrupt is triggered every 1 ms.

●

A Delay function is implemented, based on the SysTick timer end-of-count event.

The eight LEDs are toggled with a timing defined by the Delay function.

3.19

TIM asymmetric example

3.19.1

Purpose

This example describes how to configure the timer 1 and 8 peripheral to generate an

asymmetric signal.

3.19.2

Description

TIM8 is configured to generate an asymmetric signal with a programmable phase-shifted

signal on TIM8_CH2:

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TIM8 Channel 1 is configured in PWM2 mode

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TIM8 Channel 2 is configured in Asymmetric PWM2 mode

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The counter mode is center aligned mode

●

The pulse length and the phase shift are programmed consecutively in TIM8_CCR2

and TIM8_CCR1.