Peripheral firmware examples description

AN4157

18/24

Doc ID 023629 Rev 1

The TIM1 waveform can be displayed using an oscilloscope. Connect the following pins to

an oscilloscope to monitor the different waveforms:

●

PA08 (TIM1_CH1)

●

PA09 (TIM2_CH2)

●

PA10 (TIM2_CH3)

3.21

TIM complementary signals example

3.21.1

Purpose

This example shows how to perform the following operations using TIM1 timer:

●

Configure TIM1 to generate three complementary signals

●

Insert a defined dead time value

●

Use the break feature

●

Lock the desired parameters

3.21.2

Description

TIM1CLK is SystemCoreClock, and TIM1 Prescaler is set to 0.As a result, the TIM1 counter

clock is SystemCoreClock (72 MHz).

The objective is to generate a PWM signal at 17.57 kHz:

TIM1_Period = (SystemCoreClock / 17570) - 1

The three Duty cycles are computed as follows:

●

The channel 1 duty cycle is set to 50% so channel 1N is set to 50%.

●

The channel 2 duty cycle is set to 25% so channel 2N is set to 75%.

●

The channel 3 duty cycle is set to 12.5% so channel 3N is set to 87.5%.

The Timer pulse is calculated as follows:

ChannelxPulse = DutyCycle * (TIM1_Period - 1) / 100

A dead time equal to 11/SystemCoreClock is inserted between the different complementary

signals, and the Lock level 1 is selected.The break Polarity is set to high level.

The TIM1 waveform can be displayed using an oscilloscope.

●

Connect the TIM1 pins to an oscilloscope to monitor the different waveforms:

–

TIM1_CH1 pin (PA08)

–

TIM1_CH1N pin (PA07)

–

TIM1_CH2 pin (PA9)

–

TIM1_CH2N pin (PB00)

–

TIM1_CH3 pin (PA10)

–

TIM1_CH3N pin (PB01)

Note:

Connect the TIM1 break pin TIM1_BKIN pin (PB12) to the GND. To generate a break event,

switch this pin level from 0V to 3.3V.