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# y! n1 {8 S F7 y" t 本例程出自STM32MED1开发板附带光盘，其工程目录路径为：\Code Package\Peripheral Devices\06 TIM\0603_PWM_Output。* Q% e- R- C' `; z7 A0 y7 f + p( N8 |7 U7 S# V 高级定时器TIM1的通道1位于GPIOA.8引脚，此管脚正好与开发板上LED1相连，这样就可以通过观察LED1亮度变化来判断TIM1的PWM输出波形变化情况。 通过调用函数TIM1_PWMOutputConfig()可对TIM1的PWM输出进行配置。其代码定义如下： void TIM1_PWMOutputConfig(u16 Period)6 L* k$ M; d/ V3 q+ d, r2 Q {1 n9 M9 ?7 ]$ D1 i TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;0 l) f q4 D& A9 j+ e5 B1 Z; o# K GPIO_InitTypeDef GPIO_InitStructure; TIM_OCInitTypeDef TIM_OCInitStructure; NVIC_InitTypeDef NVIC_InitStructure;) K" O7 z4 g- U D1 e 1 S7 e: F+ k% Z! S% [. J RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_TIM1, ENABLE); // 1)5 `7 T. Q' h5 Y5 {0 |3 J! ^+ W' B // (20 c6 x0 f3 @5 Z' S9 T. V0 y# G GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;1 H) G+ v$ ]) g" X GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;# ?8 u- x5 h. M: t' h GPIO_Init(GPIOA, &GPIO_InitStructure); // 2)- R+ X' F: m* j* P* z 6 N' p! y) r) Y7 T. U // (3 TIM_TimeBaseStructure.TIM_Period = Period;! b9 P( L/ ?+ \) {& H* r TIM_TimeBaseStructure.TIM_Prescaler = (u16)(SystemCoreClock / 100000) - 1;+ s2 ?% A B# X6 L TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;* x$ p6 w0 p# h5 H TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); // 3) 4 h. }7 Q0 l N2 ?& P // (4 TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;5 t$ m% {. d7 V4 k7 ? TIM_OCInitStructure.TIM_Pulse = 0;& ]2 n! k3 I+ C' a# ~) e% g TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;, c8 r% A" N# Y+ a8 m. W9 l$ s/ l7 J TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;( L1 o4 |3 N) S& R" J TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; 7 _, s$ d/ E2 w7 y, {9 M9 r TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset; TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset; TIM_OC1Init(TIM1, &TIM_OCInitStructure);' g4 f' ~0 d" L // 4) v2 F" N$ Y6 y8 U7 ]2 b* } TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Disable); // 5)% L l2 _6 d7 N' w2 ]' X1 g& V, |& q6 J $ b+ F7 A5 T2 v: f TIM_ClearFlag(TIM1, TIM_FLAG_Update); // 6)( q9 Q/ X( O. R2 B& S* j TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE); // 7) TIM_UpdateRequestConfig(TIM1, TIM_UpdateSource_Global); // 8) // (99 S4 S4 y' ^. }4 n9 K6 q NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;( f$ r9 v% D5 c/ P# E: N( F/ i$ r NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); // 9)" k. z! W$ J% @- V# [ j8 k: d1 U& Y' E7 s3 r TIM_CtrlPWMOutputs(TIM1, ENABLE); // 10)/ l x" v P( R1 ^2 W- g ! [3 u6 G$ h: ~# Y+ M7 U$ \ TIM_Cmd(TIM1, ENABLE); // 11). A/ x# s; b" s) ?& D }$ L3 l4 F. l2 Q- n 代码行1）开启GPIOA及TIM1外设的时钟。代码段2）将PA.8管脚配置为复用推挽输出，因此TIM1产生的PWM信号能输出到PA.8管脚。代码段3）是对TIM1的时间基配置。代码段4）配置TIM1的输出比较通道1，将其配置为PWM模式2；起始寄存器TIM1_CCR1的值设为0；开启OC1的输出状态，关闭OC1的互补输出状态。代码行5）关闭OC1通道的预装载功能，使得每次向捕获/比较寄存器中写入的数据立即生效。代码行6）是清除TIM1的更新标志位。代码行7）是开启TIM1的更新中断，代码行8）将更新事件源限制为计时器的上溢或下溢。代码行9）是对TIM1的中断通道进行初始化。代码行10）是开启TIM1的PWM输出。代码行11）是使能TIM1外设。( n' S( L' Y% H1 w2 K5 b' B 当TIM1计数器的值达到最大时就会产生更新中断，其中断处理函数定义如下： * _- ]4 q. i0 w9 C P void TIM1_UP_IRQHandler(void)% N( Z; q3 ^9 j3 Y, i/ B+ J# n& t {5 a$ Y* j& O6 L% W# } if (TIM_GetITStatus(TIM1, TIM_IT_Update) != RESET)( {. V& F4 u7 i6 e8 K( I$ A' b. o6 w {, O2 _, N2 h& \2 @/ a$ p <span style="color: rgb(0, 0, 255);"> if ((CompareValue > PRELOAD_VALUE - INCREMENTS) || (CompareValue |
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RE:STM32MED1开发板例程解析（二）：定时器的PWM输出