STM32定时器输出带有死区时间的PWM波形

/*********************************************

    标题：定时器输出带有死区时间的PWM波形

    软件平台：MDK-ARM Standard Version4.70

    硬件平台：stm32f4-discovery    

    主频：168M

    Periph_Driver_version: V1.0.0

    

    描述：用一个定时器(TIM1)，输出带有死区时间的PWM波形，要求：死区时间为1us，CH1，CH2，CH3之间的相位差为3us，频率为50KHz

          代码参考自STM32F4-Discovery_FW_V1.1.0\Project\Peripheral_Examples\TIM_ComplementarySignals



    author：大舟

    data：2013-04-15

**********************************************/





#include "stm32f4_discovery.h"





TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

TIM_OCInitTypeDef  TIM_OCInitStructure;

TIM_BDTRInitTypeDef TIM_BDTRInitStructure;

uint16_t TimerPeriod = 0;

uint16_t Channel1Pulse = 0, Channel2Pulse = 0, Channel3Pulse = 0;



/* Private function prototypes */

void TIM_Config(void);





int main(void)

{

    /*!< At this stage the microcontroller clock setting is already configured,

    this is done through SystemInit() function which is called from startup

    file (startup_stm32f4xx.s) before to branch to application main.

    To reconfigure the default setting of SystemInit() function, refer to

    system_stm32f4xx.c file

    */



    /* TIM1 Configuration */

    TIM_Config();



    /* -----------------------------------------------------------------------

    1/ Generate 3 complementary PWM signals with 3 different duty cycles:



    In this example TIM1 input clock (TIM1CLK) is set to 2 * APB2 clock (PCLK2),

    since APB2 prescaler is different from 1 (APB2 Prescaler = 2, see system_stm32f4xx.c file).

    TIM1CLK = 2 * PCLK2

    PCLK2 = HCLK / 2

    => TIM1CLK = 2*(HCLK / 2) = HCLK = SystemCoreClock



    To get TIM1 counter clock at 168 MHz, the prescaler is computed as follows:

    Prescaler = (TIM1CLK / TIM1 counter clock) - 1

    Prescaler = (SystemCoreClock / 168 MHz) - 1 = 0



    The objective is to generate PWM signal at 17.57 KHz:

    - TIM1_Period = (SystemCoreClock / 17570) - 1



    To get TIM1 output clock at 17.57 KHz, the period (ARR) is computed as follows:

    ARR = (TIM1 counter clock / TIM1 output clock) - 1 = 9561

    



    The Three Duty cycles are computed as the following description:



    TIM1 Channel1 duty cycle = (TIM1_CCR1/ TIM1_ARR)* 100 = 50%

    TIM1 Channel2 duty cycle = (TIM1_CCR2/ TIM1_ARR)* 100 = 25%

    TIM1 Channel3 duty cycle = (TIM1_CCR3/ TIM1_ARR)* 100 = 12.5%



    The Timer pulse is calculated as follows:

    - TIM1_CCRx = (DutyCycle * TIM1_ARR)/ 100



    2/ Insert a dead time equal to (11/SystemCoreClock) ns    //这句不对，示波器里观测也不对，不是这样算的。

    

    正确的deadtime的计算方法（经理论与示波器测试成功）

    TIM_BDTRInitStructure.TIM_DeadTime=255 //这句设定的就是寄存器TIMx_BDTR的后8位，即DTG[7:0],所以最大值为255

    从下面的代码中的“第五步”中，实际上就相当于TIM1->BDTR=0x71FF;

    

    查看"STM32中文参考手册2009.pdf"的TIMx_BDTR(第248页)，列寄存器TIMx_BDTR的后8位如下：

    位7:0    UTG[7:0]: 死区发生器设置 (Dead-time generator setup) 

            这些位定义了插入互补输出之间的死区持续时间。假设DT表示其持续时间： 

            DTG[7:5]=0xx => DT=DTG[7:0] × Tdtg，        Tdtg = Tdts； 

            DTG[7:5]=10x => DT=(64+DTG[5:0]) × Tdtg，    Tdtg = 2 × Tdts；

            DTG[7:5]=110 => DT=(32+DTG[4:0]) × Tdtg，    Tdtg = 8 × Tdts；

            DTG[7:5]=111 => DT=(32+DTG[4:0]) × Tdtg，    Tdtg = 16× Tdts；

            

            例：若Tdts = 1/168us(频率为168M)，可能的死区时间DT为：

            0到756ns，        若步长时间Tdtg为1/168us；

            762ns到1512ns，    若步长时间Tdtg为2/168us；

            1524ns到3us，    若步长时间Tdtg为8/168us；

            3048ns到6us，    若步长时间Tdtg为16/168us；

    

    计算

    这里要求设置deadtime为1us，落在区间"762ns到1512ns"，所以选择公式“DTG[7:5]=10x => DT=(64+DTG[5:0])×Tdtg，Tdtg=2×Tdts；”

    列方程：(64+x)×2/168us = 1us；得x=20。所以DTG[5:0]=010100；推出DTG[7:0]=10010100=0x94。所以TIM_DeadTime=0x94。

    

    

    3/ Configure the break feature, active at High level, and using the automatic

    output enable feature



    4/ Use the Locking parameters level1.



    5/     这里要求3个通道的波形不是对齐的，所以必须设定为TIM_OCMode_Toggle模式，这样，ARR得走两趟才是一个周期，

        CCR1(TIM_Pulse)、CCR2、CCR3不同，则触发的点也不同，即错开了相位。

        注意，不管TIM_Pulse为什么值，占空比都是50%。因为ARR走一趟才取反一次。

    

    6/    要求pwm输出频率为50KHz。所以ARR=(SystemCoreClock/100000)-1 = 1679。即对时钟进行1680分频。

    

    7/    PWM1和PWM2的相位差为3us。计算如下

        因为ARR自加1的时间为(1/168M)s，即可列方程：(1/168M)x=3us，得x=504。

        即，CCR1、CCR2、CCR3之间相隔504时，PWM的相位差就为3us

        

    Note:

    SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f4xx.c file.

    Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()

    function to update SystemCoreClock variable value. Otherwise, any configuration

    based on this variable will be incorrect.

    ----------------------------------------------------------------------- */



    /* Compute the value to be set in ARR register to generate signal frequency at 17.57 Khz */

    TimerPeriod = (SystemCoreClock / 100000) - 1;    //1679;17570 ARR=9561



    /* Compute CCR1 value to generate a duty cycle at 50% for channel 1 */

    Channel1Pulse = 100;//= (uint16_t) (((uint32_t) 5 * (TimerPeriod - 1)) / 10);//CCR1_Val=4780，比较值



    /* Compute CCR2 value to generate a duty cycle at 25%  for channel 2 */

    Channel2Pulse = 604;// = (uint16_t) (((uint32_t) 25 * (TimerPeriod - 1)) / 100);//CCR2_Val=2390，比较值



    /* Compute CCR3 value to generate a duty cycle at 12.5%  for channel 3 */

    Channel3Pulse = 1108;// = (uint16_t) (((uint32_t) 125 * (TimerPeriod - 1)) / 1000);//CCR3_Val=1195，比较值



    /**@step第一步配置时钟*/

    /**@step第二步配置goio口*/

    /**@step第三步定时器基本配置*/

    /* Time Base configuration */

    TIM_TimeBaseStructure.TIM_Prescaler = 0;//时钟预分频数，对168M进行1(0+1)分频

    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//向上计数 

    TIM_TimeBaseStructure.TIM_Period = TimerPeriod;//自动重装载寄存器的值，ARR=9561

    TIM_TimeBaseStructure.TIM_ClockDivision = 0;    //采样分频 

    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;//重复寄存器，用于自动更新pwm占空比



    TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);



    /**@step第四步 PWM输出配置*/

    /* Channel 1, 2 and 3 Configuration in PWM mode */

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;                //PWM1为正常占空比模式，PWM2为反极性模式

    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;        //High为占空比高极性，此时占空比为20%；Low则为反极性，占空比为80%

    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;    //使能该通道输出

    TIM_OCInitStructure.TIM_Pulse = Channel1Pulse;    //设置占空比时间，CCR1_Val=4780，占空比为4780/(9561+1)=0.5

    

    //-------下面几个参数是高级定时器才会用到通用定时器不用配置

    TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;    //使能互补端输出

    TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;        //设置互补端输出极性

    TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;    //刹车之后输出状态Specifies the TIM Output Compare pin state during Idle state

    TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;    //刹车之后互补端输出状态

    //-------

    TIM_OC1Init(TIM1, &TIM_OCInitStructure);//对channel1进行配置

    

    TIM_OCInitStructure.TIM_Pulse = Channel2Pulse;//CCR2_Val=2390，比较值

    TIM_OC2Init(TIM1, &TIM_OCInitStructure);//对channel2进行配置

    TIM_OCInitStructure.TIM_Pulse = Channel3Pulse;//CCR3_Val=1195，比较值

    TIM_OC3Init(TIM1, &TIM_OCInitStructure);//对channel3进行配置



    /**@step第五步死区和刹车功能配置,高级定时器才有的,通用定时器不用配置*/

    /* Automatic Output enable, Break, dead time and lock configuration*/

    TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;                //运行模式下输出

    TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;                //空闲模式下输出选择 

    TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_1;                    //锁定设置，锁定级别1

    TIM_BDTRInitStructure.TIM_DeadTime = 0x94;//死区时间1us

    TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable;                    //刹车功能使能

    TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_Low;        //刹车输入极性，即刹车控制引脚接GND时，PWM停止

    TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;    //自动输出使能

    TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);

    /*    刹车控制引脚为TIM1_BKIN pin(PB.12)，将PB12接GND，channel和其互补通道，都变为刹车后的电平，具体为0还是1，要看如下两个设置：

        .TIM_OCIdleState = TIM_OCIdleState_Reset;    //刹车之后，PWM通道变为0

        .TIM_OCNIdleState = TIM_OCNIdleState_Reset;    //刹车之后，PWM互补通道变为0

        

        注意：如果没必要，还是不要开启刹车功能，因为会对PWM产生影响，特别是当PB12悬空时，波形将会有很大的波动。

              这里不打开刹车功能，即.TIM_Break = TIM_Break_Disable;

    */

    

    /**@step第六步使能端的打开*/

    /* TIM1 counter enable */

    TIM_Cmd(TIM1, ENABLE);//打开TIM1



    /* Main Output Enable */

    TIM_CtrlPWMOutputs(TIM1, ENABLE);//PWM输出使能,一定要记得打



    while (1);

}



/**

* [url=home.php?mod=space&uid=247401]@brief[/url]  Configure the TIM1 Pins.

* @param  None

* @retval None

*/

void TIM_Config(void)

{

    GPIO_InitTypeDef GPIO_InitStructure;



    /* GPIOA and GPIOB clocks enable */

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOE, ENABLE);



    /* TIM1 clock enable */

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);



    /* GPIOA Configuration: Channel 1 and 3 as alternate function push-pull */

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_10;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;

    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

    GPIO_Init(GPIOA, &GPIO_InitStructure);



    /* GPIOA Configuration: Channel 2 as alternate function push-pull */

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;

    GPIO_Init(GPIOE, &GPIO_InitStructure);



    /* GPIOB Configuration: BKIN, Channel 1N, 2N and 3N as alternate function push-pull */

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;

    GPIO_Init(GPIOB, &GPIO_InitStructure);



    /* Connect TIM pins to AF1 */

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_TIM1);    //引脚功能，查看readme.txt

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_TIM1);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource12, GPIO_AF_TIM1);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_TIM1);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_TIM1);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_TIM1);

    GPIO_PinAFConfig(GPIOE, GPIO_PinSource11, GPIO_AF_TIM1);

}

/**@end*/