How to Use STM32 TIM1 PWM with DMA for LED Fading and Motor Control

Introduction

In this tutorial, we will explore how to use the STM32 timer to generate PWM signals with DMA for smooth LED fading and motor speed control. We will specifically focus on TIM1 and PWM channel 1 on the STM32F4 series microcontrollers. By the end of this guide, you will have a working example that demonstrates how to control the brightness of an LED and the speed of a motor using PWM.

Prerequisites

• Basic understanding of STM32 microcontrollers.
• STM32 development board (e.g., STM32F4 Discovery).
• STM32CubeIDE or any other STM32 development environment.
• Familiarity with C programming.

Parts/Tools

• STM32F4 series microcontroller.
• LED and resistor (220 ohm recommended).
• DC motor with driver circuit (e.g., L298N).
• Jumper wires and breadboard.

Steps

1. Set Up Your Development Environment
   • Download and install STM32CubeIDE from the STMicroelectronics website.
   • Create a new STM32 project for your specific microcontroller.
2. Configure TIM1 for PWM Generation
   • Open the .ioc file in STM32CubeIDE.
   • Navigate to the “Timers” section.
   • Select TIM1 and configure the following settings:
     • Mode: PWM Generation CH1
     • Prescaler: Set to a suitable value (e.g., 84 for 1 MHz PWM).
     • Counter Period: Set to 1000 for 1 kHz frequency.
     • Output Compare Mode: PWM Mode 1.
   • Enable DMA for TIM1: Go to the DMA Settings and select “Update” for TIM1.
3. Configure GPIO Pins
   • Set the GPIO pin connected to the LED as “Alternate Function” with speed set to “High”.
   • Enable the GPIO pin connected to the motor driver (e.g., PWM pin).
4. Write the Code
   • Initialize TIM1 and start PWM output in your main code:

   
   void HAL_TIM_PWM_MspInit(TIM_HandleTypeDef *htim)
   {
       if(htim->Instance==TIM1)
       {
           __HAL_RCC_TIM1_CLK_ENABLE();
           // Additional DMA configuration can be added here
       }
   }
   
   void Start_PWM(void)
   {
       HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);
   }
               

   • Set Up DMA for Smooth LED Fading
     • Create a buffer for PWM values:

     
     uint32_t pwmValues[1000]; // Adjust size as needed
                     

     • Fill the buffer with values for fading:

     
     void Fill_PWM_Buffer(void)
     {
         for(uint32_t i = 0; i < 1000; i++)
         {
             pwmValues[i] = i; // Fading effect
         }
     }
                     

     • Start the DMA transfer:

     
     HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_1, pwmValues, 1000);
                     

   • Control Motor Speed
     • Adjust PWM values based on desired speed:

     
     void Set_Motor_Speed(uint32_t speed)
     {
         __HAL_TIM_SET_COMPARE(&htim1, TIM_CHANNEL_1, speed);
     }
                     

     • Call this function with a value from 0 to 1000 to control the motor speed.

Troubleshooting

• Issue: LED not fading smoothly.

  Check if the PWM frequency is set correctly in the timer settings and ensure DMA is configured properly.

• Issue: Motor not responding to speed changes.

  Verify the connections to the motor driver and ensure the PWM signal is reaching the driver input.

• Issue: Code not compiling.

  Ensure all required HAL libraries are included and the project is configured correctly in STM32CubeIDE.

Conclusion

In this tutorial, we successfully set up an STM32F4 microcontroller to control LED fading and motor speed using PWM with DMA. By following the outlined steps, you should have a functional project that demonstrates smooth transitions in LED brightness and adjustable motor speed. Experiment with different PWM frequencies and duty cycles to further enhance your understanding and application of PWM on STM32.