各位网友好。最近修改原子哥的PWM代码来控制舵机,但是驱动不了。不知道为什么。
1、舵机驱动的PWM脉冲如下图
2、舵机的信号线加了1K的上拉电阻,也不行。不加上拉电阻直接接PA7口,也不行。
代码如下,请各位前辈指点。
void TIM3_PWM_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能定时器3时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE); //使能GPIO外设和AFIO复用功能模块时钟
// RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
//设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形 GPIOB.5
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; //TIM_CH2
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIO
//初始化TIM3
TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值
TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
//初始化TIM3 Channel2 PWM模式
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //选择定时器模式:TIM脉冲宽度调制模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
TIM_OC2Init(TIM3, &TIM_OCInitStructure); //根据T指定的参数初始化外设TIM3 OC2
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); //使能TIM3在CCR2上的预装载寄存器
TIM_Cmd(TIM3, ENABLE); //使能TIM3
}
int main(void)
{
delay_init(); //延时函数初始化
NVIC_Configuration(); //设置NVIC中断分组2:2位抢占优先级,2位响应优先级
uart_init(9600); //串口初始化为9600
LED_Init(); //LED端口初始化
TIM3_PWM_Init(199,7199); //PWM频率=50hz
while(1)
{
TIM_SetCompare2(TIM3,5);
delay_ms(1000);
TIM_SetCompare2(TIM3,10);
delay_ms(1000);
TIM_SetCompare2(TIM3,15);
delay_ms(1000);
TIM_SetCompare2(TIM3,20);
delay_ms(1000);
TIM_SetCompare2(TIM3,25);
delay_ms(1000);
TIM_SetCompare2(TIM3,20);
delay_ms(1000);
TIM_SetCompare2(TIM3,15);
delay_ms(1000);
TIM_SetCompare2(TIM3,10);
delay_ms(1000);
}
}
void RCC_Configuration(void); //?????±????????
void GPIO_Configuration(void); //??????????
void TIM3_Configuration(void); //?????¨?±?÷
int main(void)
{
int a=5,fx=1;
RCC_Configuration(); //?????±????????
GPIO_Configuration();//??????????
TIM3_Configuration();//?¨?±?÷??pwm????
delay_ms(10);
while(1)
{
if(fx==1) a++;
if(fx==0) a--;
if(a==25) {fx=0;delay_ms(100);}
if(a==5) {fx=1;delay_ms(100);}
delay_ms(30);
TIM_SetCompare2(TIM3,a);
}
}
void RCC_Configuration(void) //?????±??????
{
SystemInit(); //?¨?????????±????AHB,APB1(36HMz),APB2??????(72MHz)
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);// ????APB2???è?±??
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);//????APB1???è?±??
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);//?????????????±??
}
void GPIO_Configuration(void) //GPIO????????
{
GPIO_InitTypeDef GPIO_InitStructure; //?¨???á????
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_5; //????????????GPIO????
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //?è????????????????
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP; //I/O???¤×÷×????????????ì????
GPIO_Init(GPIOB,&GPIO_InitStructure); //?ù?????¨??????????GPIOx?????÷
}
void TIM3_Configuration(void) //???????¨?±?÷3
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStruct; //?¨???á????±???
TIM_OCInitTypeDef TIM_OCInitStructure; //?¨???á????±???
GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3,ENABLE); //TIM3??????????·?????
//?¨?±?÷??????
TIM_TimeBaseStruct.TIM_Period=200; //×°??????·??§??0x0000~0xFFFF
TIM_TimeBaseStruct.TIM_Prescaler=7199; //?è???¤·???????????TIMx?±??????
//72MHz / 7200 = 10000Hz ,????×???10000
TIM_TimeBaseStruct.TIM_ClockDivision=0; //?è???±??·???±????¨+1??
TIM_TimeBaseStruct.TIM_CounterMode=TIM_CounterMode_Up;//?????÷???????ò??????
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStruct); //?ù????????????TIMx?±???ù??????
//PWM??????
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; //TIM?????í???÷??????1
TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable;//????
TIM_OCInitStructure.TIM_OCPolarity=TIM_OCPolarity_High;//TIM????±???????
TIM_OC2Init(TIM3,&TIM_OCInitStructure); //??????TIM3
TIM_OC2PreloadConfig(TIM3,TIM_OCPreload_Enable); //?¤×°??
TIM_Cmd(TIM3,ENABLE); //????TIM3???è
}
我刚写出来的,舵机180度来回转,信号线插在PB5,因为我用了映射,通道2
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PWM频率50Hz,周期就是20ms,舵机不是 -90度=0.5ms吗?为什么 而不是TIM_SetCompare2(TIM3,0.5);
psc设为7199,可得定时器单次计数时间为100us,arr设为199,即得PWM脉冲宽度为(199+1)*100us=20ms,“TIM_SetCompare2(TIM3,5);”
中的5,写入TIM_CRR2寄存器,的5*100us=0.5ms
---------------------------------
TIM_TimeBaseStruct.TIM_Period=200; //×°??????·??§??0x0000~0xFFFF
这一行的200应该改为199吧,不是有加1的吗
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