Getting Started with STM32G0 and STM32CubeIDE: Timer in PWM Mode

In this guide, we shall cover the PWM mode in the timer and fade an LED connected to 1 on the timer channel.

In this guide, we shall cover the following:

• What is PWM.
• Developing the driver.
• Connection.
• Results.

1. What is PWM:

Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), is a technique used to represent a signal as a rectangular wave with a varying duty cycle (and sometimes a varying period). Let’s break it down:

1. Duty Cycle: The duty cycle refers to the ratio of the time the signal is “on” (high) to the total time of one complete cycle. It is expressed as a percentage. For example, if a signal is on for 60% of the time and off for 40%, the duty cycle is 60%.
2. Average Power Control: PWM is particularly useful for controlling the average power or amplitude delivered by an electrical signal. By switching the supply between 0% and 100% at a rate faster than the load can respond, we can effectively control the average power delivered to the load.
3. Applications:
   • Motor Control: PWM is commonly used to control motors (such as in fans, pumps, and robotics) because motors are not easily affected by discrete switching.
   • Solar Panels: It’s a key method for controlling the output of solar panels to match battery requirements.
   • Digital Controls: PWM works well with digital controls, allowing precise duty cycle adjustments.
   • Communication Systems: In some cases, PWM duty cycles have been used to convey information over communication channels.
4. Switching Frequency: The switching frequency (how often the signal switches on and off) varies depending on the application. It can range from several times a minute (e.g., electric stoves) to tens or hundreds of kilohertz (e.g., audio amplifiers).
5. Advantages:
   • Low power loss in switching devices (almost zero current when off).
   • Works well with digital control systems.
   • Used in various applications due to its flexibility.
6. Disadvantages:
   • Choosing the right switching frequency is crucial for smooth control.
   • Too high a frequency can stress mechanical components.
   • Too low a frequency can cause load oscillations.

In summary, PWM allows precise control of average power delivery by rapidly switching the signal on and off.

2. Developing the Driver:

Create new project with name of TIM_PWM.

open clock configuration tab as following:

Notice the value of APB Timer clocks which is 16MHz in this case.

Now, from Pinout and Configuration tab, enable timer 3:

Save the project and this should generate the project.

In user code 2 in main function:

Enable timer 3 in PWM mode as following:

HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1);

In user code 3, we shall vary the duty cycle as following:

	  for (int i=0;i<100;i++)
	  {
		  TIM3->CCR1=i;
		  HAL_Delay(10);
	  }
	  HAL_Delay(50);
	  for (int i=100;i>0;i--)
	  {
		  TIM3->CCR1=i;
		  HAL_Delay(10);
	  }
	  HAL_Delay(50);

By using the CCRx register of the timer, it allows us to change the duty cycle with ease.

The duty cycle can be calculate as following:

3. Connection:

The connection as following and you will need those extra componets:

• Breadboard.
• Hockup wires.
• LED (any color).
• 100Ohm resistor.

The connection as following:

4. Results:

Happy coding 🙂