Advanced Timer (TIM)

Tutorial demonstrating advanced timer (TIM8) PWM driving motor.

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The tutorial only introduces the standard library project code

Hardware connection

Since we have configured a special connection line, we only need to install it to the corresponding interface:

Control principle

Use the PWM output function of TIM8 of the advanced timer on the STM32F103RCT6 development board to change the duty cycle of the PWM signal to control the speed of the motor rotation.

• PWM (Pulse Width Modulation)

PWM is the abbreviation of pulse width modulation, which is a technology that controls the level by adjusting the pulse width of the signal.

Period: The duration of a complete PWM waveform;

Duty cycle: The ratio of the duration of the high level to the period time;

Frequency: The reciprocal of the period is called the frequency, that is, the number of PWM periods generated per second;

• Advanced timer

Pin definition

Software code

Since the default function of the pin is the normal IO pin function, we need to use the multiplexing function.

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Product supporting materials source code path: Attachment → Source code summary → 1.Base_Course → 9.Advanced_Timer

Control function

The tutorial only briefly introduces the code, you can open the project source code to read the details.

Balance_Motor_Init

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void Balance_Motor_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE); //Enable PC port clock
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9; //Port configuration
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //Push-pull output
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M
    GPIO_Init(GPIOC, &GPIO_InitStructure); //Initialize GPIOC according to the set parameters
}

Balance_PWM_Init

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void Balance_PWM_Init(u16 arr,u16 psc)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);
    TIM_DeInit(TIM8);
    TIM_TimeBaseStructure.TIM_Period = arr - 1; //Set the value of the auto-reload register period to load the activity at the next update event
    TIM_TimeBaseStructure.TIM_Prescaler = psc; //Set the prescaler value used as the divisor of the TIMx clock frequency. No division
    TIM_TimeBaseStructure.TIM_ClockDivision = 0; //Set the clock division: TDTS = Tck_tim
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM up counting mode
    TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure); //Initialize the time base unit of TIMx according to the parameters specified in TIM_TimeBaseInitStruct

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //Select timer mode: TIM pulse width modulation mode 1
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //Comparison output enable
    TIM_OCInitStructure.TIM_Pulse = 0; //Set the pulse value to be loaded into the capture comparison register
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //Output polarity: TIM output comparison polarity high

    TIM_OC1Init(TIM8, &TIM_OCInitStructure); //Initialize peripheral TIMx according to the parameters specified in TIM_OCInitStruct
    TIM_OC2Init(TIM8, &TIM_OCInitStructure); //Initialize peripheral TIMx according to the parameters specified in TIM_OCInitStruct
    TIM_OC3Init(TIM8, &TIM_OCInitStructure); //Initialize peripheral TIMx according to the parameters specified in TIM_OCInitStruct
    TIM_OC4Init(TIM8, &TIM_OCInitStructure); //Initialize peripheral TIMx according to the parameters specified in TIM_OCInitStruct

    TIM_CtrlPWMOutputs(TIM8,ENABLE); //MOE main output enable

    TIM_OC1PreloadConfig(TIM8, TIM_OCPreload_Enable); //CH1 preload enable
    TIM_OC2PreloadConfig(TIM8, TIM_OCPreload_Enable); //CH2 preload enable
    TIM_OC3PreloadConfig(TIM8, TIM_OCPreload_Enable); //CH3 preload enable
    TIM_OC4PreloadConfig(TIM8, TIM_OCPreload_Enable); //CH4 preload enable

    TIM_ARRPreloadConfig(TIM8, ENABLE); //Enable TIMx preload register on ARR

    /* TIM8 enable counter */
    TIM_Cmd(TIM8, ENABLE); //Enable timer 8
}

Set_Pwm

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void Set_Pwm(int motor_left,int motor_right)
{
    if(motor_left == 0)// stop
    {
        L_PWMA = 0;
        L_PWMB = 0;
    }
    if(motor_right == 0)
    {
        R_PWMA = 0;
        R_PWMB = 0;
    }
    //left wheel
  if(motor_left>0)   // forward  
    {
        L_PWMB = myabs(motor_left);
        L_PWMA = 0;
    }       
    else // backward
    {
        L_PWMB = 0;
        L_PWMA = myabs(motor_left);
    }
    //right wheel
    if(motor_right>0) // forward 
    {
        R_PWMA = myabs(motor_right);
        R_PWMB = 0;
    }
    else // backward
    {
        R_PWMA = 0;
        R_PWMB = myabs(motor_right);    
    }
}

myabs

int myabs(int a)
{          
    int temp;
    if(a<0)  temp=-a;  
    else temp=a; 
    return temp;
}

Experimental phenomenon

The Advanced_Timer.hex file generated by the project compilation is located in the OBJ folder of the Advanced_Timer project. Find the Advanced_Timer.hex file corresponding to the project and use the FlyMcu software to download the program to the development board.

After the program is successfully downloaded: the two motors will continue to run according to the rule of moving forward for 2s, stopping for 1s, moving backward for 2s, and stopping for 1s.

When using the serial port debugging assistant, you need to pay attention to the serial port settings. If the settings are wrong, the phenomenon may be inconsistent