The difference between the PWM configuration of TIM1 and TIM2 of STM8S series microcontrollers

Why can't STM8's PWM be output using TIM1, but TIM2 can? The following program code is written for TIM1's PWM output.

STM8S series microcontroller

PC1 pin is used to control the PWM output, namely TIM1_CH1 channel

PC2 pin is used to control the PWM output, namely TIM1_CH2 channel

PC3 pin is used to control the PWM output, namely TIM1_CH3 channel

//PWM initialization

void Driver_PWMON(u8 ch,u8 Num)

{ 

    //Open TIM1 clock

    CLK->PCKENR1 |= CLK_PCKENR1_TIM1;

    //Set PWM frequency, Fpwm=Fmaster/TIM2_ARR 

    //Here Fpwm = 2000000/100 = 20K

    TIM1->ARRH = 0;

    TIM1->ARRL = 100;

    //Start counting and start PWM output

    TIM1->BKR |= TIM1_BKR_MOE;

    switch(ch)

    {

        case 1:

            TIM1->CCMR1 |= 0x70; //Set TIM1_CH1 to PWM mode 2, effective level is high

            pwm_ch_on(1); //Turn on TIM1_CH1 channel output

            TIM1->CCR1H = 0; // Initialize PWM channel duty cycle 1:1   

            TIM1->CCR1L = Num;

            break;

        case 2:

            TIM1->CCMR2 |= 0x70; //Set TIM1_CH2 to PWM mode 2, effective level is high

            pwm_ch_on(2); //Turn on TIM1_CH1 channel output

            TIM1->CCR2H = 0; // Initialize PWM channel duty cycle 1:1   

            TIM1->CCR2L = Num;

            break;

        case 3:

            TIM1->CCMR3 |= 0x70; //Set TIM1_CH3 to PWM mode 2, effective level is high

            pwm_ch_on(3); //Turn on TIM1_CH1 channel output

            TIM1->CCR3H = 0; // Initialize PWM channel duty cycle 1:1   

            TIM1->CCR3L = Num;

            break;

        case 4:

            TIM1->CCMR4 |= 0x70; //Set TIM1_CH4 to PWM mode 2, effective level is high

            pwm_ch_on(4); //Turn on TIM1_CH1 channel output

            TIM1->CCR4H = 0; // Initialize PWM channel duty cycle 1:1   

            TIM1->CCR4L = Num;

            break;

    }

    TIM1->CR1 |= TIM1_CR1_CEN;

}

//PWM duty cycle adjustment 0-100

void Driver_PWMSet(u8 ch,u8 Num)

{

    if(Num > 100)

          return;

    switch(ch)

    {

        case 1:

             TIM1->CCR1L = Num;

            break;

        case 2:

            TIM1->CCR2L = Num;

            break;

        case 3:

            TIM1->CCR3L = Num;

            break;

        case 4:

            TIM1->CCR4L = Num;

            break;

    }

}

//Open the PWM channel

void pwm_ch_on(u8 ch)

{

    switch(ch)

    {

        case 1:

            TIM1->CCER1 |= 0x01;

            break;

        case 2:

            TIM1->CCER1 |= 0x10;

            break;

        case 3:

            TIM1->CCER2 |= 0x01;

            break;

        case 4:

            TIM1->CCER2 |= 0x10;

            break;

    }

}

//Close the PWM channel

void pwm_ch_close(u8 ch)

{

    switch(ch)

    {

        case 1:

            TIM1->CCER1 &= ~0x01;

            break;

        case 2:

            TIM1->CCER1 &= ~0x10;

            break;

        case 3:

            TIM1->CCER2 &= ~0x01;

            break;

        case 4:

            TIM1->CCER2 &= ~0x10;

            break;

    }

}

//Run the main function

int main(void)

{ 

  Driver_PWMON(1,0);

  Driver_PWMON(2,0);

  Driver_PWMON(3,0);

  while(1)

  { 

     u8 a= 0,b=0;

    for(b=1; b<4; b++)

    {

      for(a=1;a<99;a++)

      {

        Driver_PWMSet(b,a);

        delay_ms(5);

      }

      for(a=99;a>0;a--)

      {

        Driver_PWMSet(b,a);

        delay_ms(5);

      }

    }

  }

}

The difference between TIM2 and TIM1 is: TIM1->BKR |= TIM1_BKR_MOE;

TIM2 does not need to configure this register.

The output enable of OCi is controlled by the combination of CCiE, MOE, OISi, OSSR and OSSI bits (in TIM1_CCERi and TIM1_BKR registers).