PWM output configuration of STM8S105 series microcontroller

Timer resources of STM8S105xx:

(1) Two 16-bit general-purpose timers (TIM2, TIM3) with 2+3 CAPCOM channels (IC, OC or PWM);

(2) Advanced control timer (TIM1): 16 bits, 4 CAPCOM channels (capture/compare channels), 3 complementary outputs, dead zone insertion and flexible synchronization;

(3) 8-bit basic timer (TIM4) with 8-bit prescaler;

(4) Automatic wake-up timer;

(5) 2 watchdog timers: window watchdog and independent watchdog.

There are differences in the initialization configuration of the PWM output function using the advanced control timer and the ordinary general timer. The following is a simple analysis:

TIM1 - 16-bit advanced control timer

16-bit up, down and bidirectional auto-reload counter with 16-bit prescaler

TIM2, TIM3——16-bit general-purpose timer

16-bit up-counting and auto-reload counter

15-bit prescaler, the division factor can be adjusted to a power of 2 value between 1 and 32768

TIM4 - 8-bit basic timer

8-bit auto-load adjustable prescaler, ratio selectable as power of 2 between 1 and 128

Configure the PWM output function of TIM1_CH1:

void Time1_Init()

{

      CLK->CKDIVR=0x00; 

      /*

     * Here, the counting frequency of TIM2 is set to 16M/1600=10000Hz

     */

      TIM1_TimeBaseInit(1599,TIM1_COUNTERMODE_UP,2000,0); //Division by 1600, counting up, TIM1_ARR=1000, repeat counter is 0

    /*OC1 initialization: PWM1 mode

                               Output Enable

                               Complementary output disabled

                               CCR1=1000, duty cycle is 50%

                               Output valid polarity is high

                               Complementary output effective polarity is high (no effect)

                               Output high when idle

                               Complementary output high when idle (no function)

     */

      TIM1_OC1Init(TIM1_OCMODE_PWM1,

      TIM1_OUTPUTSTATE_ENABLE,

      TIM1_OUTPUTNSTATE_DISABLE,

      1000,

      TIM1_OCPOLARITY_HIGH,

      TIM1_OCNPOLARITY_HIGH,

      TIM1_OCIDLESTATE_SET,

      TIM1_OCNIDLESTATE_SET);

      TIM1_OC1PreloadConfig(ENABLE);  

      TIM1_CtrlPWMOutputs(ENABLE); //PWM output enable

      TIM1_Cmd(ENABLE); //Timer starts counting

} 

Configure the PWM output function of TIM2_CH1:

void TIMER2_PWMInit(unsigned short timebase,unsigned short t)

{

      TIM2_DeInit();  

      /*

       * TIM2 Frequency = TIM2 counter clock/(ARR + 1) 

       * Here, the counting frequency of TIM2 is set to 16M/32/(timebase+1)=1K

       */

      TIM2_TimeBaseInit(TIM2_PRESCALER_32, timebase); 

      /* 

       * PWM1 Mode configuration: Channel1

       * TIM2 Channel1 duty cycle = [TIM2_CCR1/(TIM2_ARR + 1)] * 100 = 50%

       * TIM2 Channel2 duty cycle = [TIM2_CCR2/(TIM2_ARR + 1)] * 100 = 50%

       */ 

      /* Test channel 1 */

      TIM2_OC1Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, t, TIM2_OCPOLARITY_HIGH);

      TIM2_OC1PreloadConfig(ENABLE);

      TIM2_Cmd(ENABLE);

}