Getting Started with STM32G0 and STM32CubeIDE: Generate PWM with it’s complementary signal

In this continuous guide of PWM with DMA on STM32G0, we shall add the complementary signal with the generated PWM.

In this guide, we shall cover the following:

• What is complementary signal of PWM.
• STM32CubeMX Configuration.
• Driver development.
• Results.

1. What is Complementary Signal of PWM:

A Complementary Signal of PWM refers to two pulse-width modulation (PWM) signals that are inverses of each other. These signals are often used in power electronics, such as in the control of H-bridges, full-bridge converters, or other switching circuits where pairs of transistors are used.

Key Characteristics:

• Duty Cycle Inversion: When one signal is high, the complementary signal is low, and vice versa. For example, if the primary PWM signal has a duty cycle of 40%, the complementary signal will have a duty cycle of 60%.
• Dead Time: A small, controlled delay (dead time) is typically introduced between the transitions of the two signals to prevent both switches (e.g., transistors or MOSFETs) from being on simultaneously, which could cause a short circuit.

Applications:

• Motor Control: In H-bridge configurations for driving motors, complementary PWM signals are used to control the direction and speed of the motor.
• DC-DC Converters: Complementary PWM signals are used in synchronous buck converters and other types of converters to control the switching of transistors.
• Inverters: In inverters, complementary PWM signals are used to create AC waveforms from DC sources.

Complementary PWM signals are crucial for efficient and safe operation in many power electronic circuits.

2. STM32CubeMX Configuration:

Continue from the previous guide here.

Open PWM_DMA.ioc file as following:

From timers, select TIM1 and configure it as following:

Channel 1 as PWM Generation CH1 CH1N. In similar manner, for channel 2.

You can noticed that PA7 has been selected as TIM1_CH1N and PB0 as TIM1_CH2N.

Save the project and this will generate the new code.

3. Driver Development:

In main.c.

In user code begin 2 section:

  HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_1, lookUp1, 200);
  HAL_TIMEx_PWMN_Start(&htim1, TIM_CHANNEL_1);

First function is explained in the previous guide.

The function HAL_TIMEx_PWM_Start, it will start the PWM generate on the complementary pin of the PWM.

The function takes two arguments:

• Pointer to the timer which is timer1 as htim1.
• Timer channel which is timer channel 1.

For the second channel:

  HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_2, lookUp2, 200);
  HAL_TIMEx_PWMN_Start(&htim1, TIM_CHANNEL_2);

Thats it for the code.

Save the project, build it and run it on your STM32G070.

4. Results:

By using logic analyzer, probe PA7 and PA8 which they are TIM1_CH1N and TIM1_CH1 respectively.

You should get the following for both channel:

Note that when one channel is high, the other is low and vice versa.

Happy coding 😉