[STM32] How to configure Timer 1, Channel 3 is PWM 1kHz, duty cycle 20% to control BLDC motor

 To configure Timer1 for a 1 kHz PWM signal with a 20% duty cycle on an STM32H7S3L8 microcontroller, follow these steps:

1. Understand the Timer Parameters

• PWM Frequency: 1 kHz → Period = 1 ms.
• Duty Cycle: 20% → ON time = 0.2 ms.

The timer’s clock frequency is derived from the APB clock (e.g., TIMCLK). Let’s assume you know the APB clock frequency. The Timer prescaler and auto-reload register (ARR) define the PWM frequency.

2. Compute Timer Parameters

Formula:

$$\text{PWM Frequency} = \frac{\text{Timer Clock}}{\text{(Prescaler + 1) * (ARR + 1)}}$$

For 1 kHz PWM:

$$ARR = \frac{\text{Timer Clock}}{\text{PWM Frequency} * (\text{Prescaler + 1)}} - 1$$

• Prescaler: Adjust it to reduce the timer clock to a manageable range.
• ARR: Defines the PWM period.
• CCR1 (Compare Register): Controls the duty cycle.

Example: If TIMCLK = 200 MHz:

• Choose Prescaler = 199 (to divide TIMCLK to 1 MHz).
• ARR = 999 (to set a 1 kHz PWM frequency).
• CCR1 = $ARR * \text{Duty Cycle} = 999 * 0.2 = 199$.

3. Code Example

Using HAL in STM32CubeIDE:

IOC 

#include "main.h"

void PWM_Config(void)
{
    TIM_HandleTypeDef htim1;
    TIM_OC_InitTypeDef sConfigOC = {0};

    // Initialize Timer1
    __HAL_RCC_TIM1_CLK_ENABLE(); // Enable TIM1 clock

    htim1.Instance = TIM1;
    htim1.Init.Prescaler = 199;           // Prescaler to divide clock to 1 MHz
    htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
    htim1.Init.Period = 999;              // ARR value for 1 kHz PWM
    htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
    htim1.Init.RepetitionCounter = 0;
    HAL_TIM_PWM_Init(&htim1);

    // Configure PWM mode for Channel 1
    sConfigOC.OCMode = TIM_OCMODE_PWM1;
    sConfigOC.Pulse = 199;                // Duty cycle = 20%
    sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
    sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
    HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1);

    // Start PWM on Channel 1
    HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);
}