STM8S---Timer generates PWM (TIM2)

1 Description

• Use STM8S internal clock (HSI);

• PWM mode 2;

• The duty cycle is 50% and the frequency is 2Hz (convenient for testing LED lights);

• PD2 port is connected to an external LED light, and PD2 port outputs PWM wave;

• System clock initialization is very important: CLK_CKDIVR |= 0x08;

2 Code

/*

TIM2_CH3 PWM

PD2 output

*/

#include

void CLK_init(void)

{

    CLK_ICKR |= 0X01; //Enable internal high-speed clock HSI

    CLK_CKDIVR |= 0x08; //16M internal RC is divided by 2 and the system clock is 8M

    while(!(CLK_ICKR&0x02)); //HSI is ready 

    CLK_SWR=0xe1; //HSI is the main clock source 

}

void Init_Tim2(void)

{

    TIM2_CCMR3 |= 0X70; //Set the output comparison mode of timer 2 three channels (PD2)

    TIM2_CCMR3 |= 0X04; //Output compare 3 preload enable

    TIM2_CCER2 |= 0x03; //Channel 3 is enabled, low level is valid, and it is configured as output

    //Initialize the clock divider to 1, that is, the clock frequency of the counter is Fmaster=8M/64=0.125MHZ

    TIM2_PSCR = 0X06;   

    // Initialize the auto-load register to determine the frequency of the PWM square wave, Fpwm=0.125M/62500=2HZ

    TIM2_ARRH = 62500/256;

    TIM2_ARRL = 62500%256;

    // Initialize the comparison register to determine the duty cycle of the PWM square wave: 5000/10000 = 50%

    TIM2_CCR3H = 31250/256;

    TIM2_CCR3L = 31250%256;

    // Start counting; update interrupt disable

    TIM2_CR1 |= 0x81;

    //TIM2_IER |= 0x00;        

}

void Init_GPIO(void)

{

    /*Set to push-pull output, PD2 is connected to LED light*/

    PD_DDR |= 0X04; //Set PD2 port to output mode

    PD_CR1 |= 0X04; //Set PD2 port to push-pull output mode

    PD_CR2 &= 0XFD;

    PA_DDR |= 0X08; //Set PA3 port to output mode

    PA_CR1 |= 0X08; //Set PA3 port to push-pull output mode

    PA_CR2 |= 0XF7;

}

void main(void)

{

    CLK_init();

    Init_GPIO();

    Init_Tim2();

    while (1);

}