嵌入式PWM控制电路.doc

嵌入式作业院系： 班级： 姓名： 学号： PWM控制电路一、要求：PWM 控制电路，要求能够输出8路任意频率，任意占空比的 PWM波。二、流程图： 开始 系统初始化 引脚初始化 定时器参数计算 定时器设置 PWM生成三、具体步骤 int main(void) unsigned char i = 0;for(i = 0; i 4; i+)Cnt3i= 0;T3i = 0;R3i = 0;Rh3i = 0;Rl3i = 0;F3i = 0; Cnt4i= 0;T4i = 0;R4i = 0;Rh4i = 0;Rl4i = 0;F4i = 0;/t的范围为（065536）T30 = 450; /F=40KT31 = 600; /F=30KT32 = 900; /F=20KT33 = 1800; /F=10K/F(占空比)的范围为（0100）F30 = 40;F31 = 30;F32 = 20;F33 = 10; /t的范围为（065536）T40 = 750; /F=40KT41 = 600; /F=30KT42 = 900; /F=20KT43 = 1400; /F=10K/F(占空比)的范围为（0100）F40 = 40;F41 = 30;F42 = 20;F43 = 50; SystemInit(); GPIO_Config(); TIM5_Init();/* TIM3 PWM波输出初始化，并使能TIM3 PWM输出 */TIM5_PWM_Init();TIM4_Init();TIM4_PWM_Init(); while (1) 经查阅资料得知，用STM32定时器的PWM模式只能在4个通道上产生频率相同但占空比不同的PWM 波，要想输出PWM频率可调，占空比可调，必须得使用比较输出模式。使用定时器的输出比较触发模式，通过改变各通道比较寄存器（如CCR1）中的值，改变PWM的占空比，在每次各通道匹配中断中改变CCR1的值。1、I/O配置配置TIM3和TIM4的共8个通道所占用的I/O口。void GPIO_Config(void) GPIO_InitTypeDef GPIO_InitStructure; RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3 |RCC_APB1Periph_TIM4 , ENABLE); RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_GPIOD, ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7; 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); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 |GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9; GPIO_Init(GPIOB, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin =GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15 ; GPIO_Init(GPIOD, &GPIO_InitStructure);2、占空比设置int main(void) unsigned char i = 0;for(i = 0; i 4; i+)Cnt3i= 0;T3i = 0;R3i = 0;Rh3i = 0;Rl3i = 0;F3i = 0; Cnt4i= 0;T4i = 0;R4i = 0;Rh4i = 0;Rl4i = 0;F4i = 0;/t的范围为（065536）T30 = 450; /F=40KT31 = 600; /F=30KT32 = 900; /F=20KT33 = 1800; /F=10K/F(占空比)的范围为（0100）F30 = 40;F31 = 30;F32 = 20;F33 = 10; /t的范围为（065536）T40 = 750; /F=40KT41 = 600; /F=30KT42 = 900; /F=20KT43 = 1400; /F=10K/F(占空比)的范围为（0100）F40 = 40;F41 = 30;F42 = 20;F43 = 50;3、设置定时器中断 void TIM3_NVIC_Configuration(void) NVIC_InitTypeDef NVIC_InitStructure; NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); void TIM4_NVIC_Configuration(void) NVIC_InitTypeDef NVIC_InitStructure; NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 4; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); 4、计算出输出高、低电平时间Rh3i和Rh4i=通道i的高电平时间；Rl3i和Rl4i =通道i的低电平时间，把Rl3i 、Rl4i写入对应的输出比较寄存器，并启动计数器开始计数。void TIM3_Init(void)unsigned char i = 0;for(i = 0; i 4; i+)Rh3i = (T3i * F3i) / 100;Rl3i = T3i - Rh3i;R30 = Rl30;R31 = Rl31;R32 = Rl32;R33 = Rl33;CCR3_1 = R30;CCR3_2 = R31;CCR3_3 = R32;CCR3_4 = R33;void TIM4_Init(void) unsigned char i = 0; for(i = 0; i 65535)R30=R30-65535;CCR3_1=R30;TIM_SetCompare1(TIM3,CCR3_1); void TIM4_IRQHandler(void)if(TIM_GetITStatus(TIM4,TIM_IT_CC1)!=RESET)TIM_ClearITPendingBit(TIM4,TIM_IT_CC1);C