How to use PWM on the STM32F407 microcontroller?

 Here's a complete guide to using PWM on the STM32F407 microcontroller using TIM4 and GPIO pin PD12 (which maps to TIM4_CH1) — commonly used on STM32F4 Discovery boards.

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 Goal

Generate PWM signal on PD12 (TIM4 Channel 1) using STM32F407 and HAL drivers via STM32CubeMX + STM32CubeIDE.

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 Required Tools

• STM32F407 MCU or Discovery board

• STM32CubeMX

• STM32CubeIDE

• USB cable, LED, or oscilloscope (to observe PWM)

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 Step-by-Step Instructions

1. STM32CubeMX Configuration

a. Select Device

• Open CubeMX and choose STM32F407VGTx (or your variant).

b. Configure Pin

• Click on pin PD12, set as TIM4_CH1 → PWM Generation CH1.

c. Configure Timer 4

• Go to Timers → TIM4 → Mode → PWM Generation Channel 1.

• Set:

  • Prescaler: 83 → 84 MHz / (83+1) = 1 MHz timer frequency

  • Counter Period (ARR): 999 → PWM frequency = 1 MHz / 1000 = 1 kHz

  • Pulse: 500 → 50% duty cycle

d. Clock Configuration

• Ensure the system clock is at 84 MHz (from HSE or HSI with PLL).

e. Project Settings

• Name the project (e.g., PWM_TIM4), set the toolchain to STM32CubeIDE.

• Click Generate Code.

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2. STM32CubeIDE Code (main.c)

Add this to your main.c inside int main(void) after HAL initialization:

c

HAL_TIM_PWM_Start(&htim4, TIM_CHANNEL_1); // Start PWM on TIM4_CH1

// Set duty cycle to 50%
__HAL_TIM_SET_COMPARE(&htim4, TIM_CHANNEL_1, 500);

To change duty cycle dynamically:

c

uint16_t duty = 750; // 75% of 1000
__HAL_TIM_SET_COMPARE(&htim4, TIM_CHANNEL_1, duty);

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 Example PWM Frequency & Duty Cycle Calculation

Prescaler	Period (ARR)	Timer Freq	PWM Freq
83	999	1 MHz	1 kHz
83	99	1 MHz	10 kHz

Duty cycle (%) = (CCR1 / ARR) * 100

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Debugging & Testing

• Connect an LED with resistor to PD12 or measure with an oscilloscope.

• You should see PWM square wave output.

• Try varying CCR1 in a loop to change brightness:

c

for (int i = 0; i < 1000; i++) {
    __HAL_TIM_SET_COMPARE(&htim4, TIM_CHANNEL_1, i);
    HAL_Delay(1);
}

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 Optional: Use Other Channels or Pins

Timer	Channel	Pin
TIM4	CH2	PD13
TIM4	CH3	PD14
TIM4	CH4	PD15
TIM3	CH1	PA6
TIM2	CH1	PA0