STM32定时器输出多路可调频率方波实现细节记录

最近有个项目要用到多达16路的可调频率的方波，于是想到用stm32的定时器输出比较翻转模式（TIM_OCMode_Toggle），一个定时器可以产生4路的信号输出。仔细阅读手册，并且参考了官方的例程，大体过程实现过程是：打开一个TIMx计数器，再打开TIMx的一路或几路输出比较器（共4路），都配置好以后，计数器开始计数，当计数器里的值和比较寄存器里的值相等时，产生输出比较中断，在中断中将计数器中的值读出，与翻转周期相加再写道比较寄存器中。

先以timer3为例，上代码：

TIM3配置部分：

  1 /******************** (C) COPYRIGHT 2015**************************
  2  * ÎÄ¼þÃû  £ºhal_TIM.c
  3  * ÃèÊö    £º
  4  * ÊµÑéÆ½Ì¨£ºTHE ONE 103
  5  * Ó²¼þÁ¬½Ó£º---------------------
  6  *          |  PA.06: (TIM3_CH1)  |
  7  *          |  PA.07: (TIM3_CH2)  |
  8  *          |  PB.00: (TIM3_CH3)  |
  9  *            |  PB.01: (TIM3_CH4)  |
 10  *           ---------------------
 11  * ¿â°æ±¾  £ºST3.5.0
 12  * ×÷Õß    £º´ú¾°¾©
 13 **********************************************************************************/
 14 #include "hal_TIM.h"
 15
 16 /* ÆµÂÊ±ä»¯È«¾Ö±äÁ¿ */
 17 uint16_t CCR1_Val = 0x8000;
 18 uint16_t CCR2_Val = 0x4000;
 19 uint16_t CCR3_Val = 0x2000;
 20 uint16_t CCR4_Val = 0x1000;
 21
 22
 23 /*
 24  * º¯ÊýÃû£ºTIM3_GPIO_Config
 25  * ÃèÊö  £ºÅäÖÃTIM3¸´ÓÃÊä³öPWMÊ±ÓÃµ½µÄI/O
 26  * ÊäÈë  £ºÎÞ
 27  * Êä³ö  £ºÎÞ
 28  * µ÷ÓÃ  £ºÄÚ²¿µ÷ÓÃ
 29  */
 30 static void TIM3_GPIO_Config(void)
 31 {
 32   GPIO_InitTypeDef GPIO_InitStructure;
 33
 34     /* TIM3 clock enable */
 35     //PCLK1¾¹ý2±¶Æµºó×÷ÎªTIM3µÄÊ±ÖÓÔ´µÈÓÚ72MHz
 36   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
 37
 38   /* GPIOA and GPIOB clock enable */
 39   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB, ENABLE);
 40
 41   /*GPIOA Configuration: TIM3 channel 1 and 2 as alternate function push-pull */
 42   GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | GPIO_Pin_7;
 43   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;            // ¸´ÓÃÍÆÍìÊä³ö
 44   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
 45
 46   GPIO_Init(GPIOA, &GPIO_InitStructure);
 47
 48   /*GPIOB Configuration: TIM3 channel 3 and 4 as alternate function push-pull */
 49   GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0 | GPIO_Pin_1;
 50
 51   GPIO_Init(GPIOB, &GPIO_InitStructure);
 52 }
 53
 54 /*
 55  * º¯ÊýÃû£ºTIM3_Mode_Config
 56  * ÃèÊö  £ºÅäÖÃTIM3Êä³öµÄÐÅºÅµÄÄ£Ê½
 57  * ÊäÈë  £ºÎÞ
 58  * Êä³ö  £ºÎÞ
 59  * µ÷ÓÃ  £ºÄÚ²¿µ÷ÓÃ
 60  */
 61 static void TIM3_Mode_Config(void)
 62 {
 63     TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
 64     TIM_OCInitTypeDef  TIM_OCInitStructure;
 65
 66   /* Time base configuration */
 67   TIM_TimeBaseStructure.TIM_Period = 65535;
 68   TIM_TimeBaseStructure.TIM_Prescaler = 2;        //ÉèÖÃÔ¤·ÖÆµ£º²»Ô¤·ÖÆµ£¬¼´Îª72MHz
 69   TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;    //ÉèÖÃÊ±ÖÓ·ÖÆµÏµÊý£º²»·ÖÆµ
 70   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //ÏòÉÏ¼ÆÊýÄ£Ê½
 71   TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
 72
 73   /* PWM1 Mode configuration: Channel1 */
 74   TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;        //ÅäÖÃÎª±È½ÏÊä³öÄ£Ê½·×ªÄ£Ê½
 75     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  //µ±¶¨Ê±Æ÷¼ÆÊýÖµÐ¡ÓÚCCR1_ValÊ±ÎªµÍµçÆ½
 76
 77     //Ê¹ÄÜ±È½ÏÊä³ö·×ªÄ£Ê½Í¨µÀ1
 78   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
 79   TIM_OCInitStructure.TIM_Pulse = CCR1_Val;       //ÉèÖÃÌø±äÖµ£¬µ±¼ÆÊýÆ÷¼ÆÊýµ½Õâ¸öÖµÊ±£¬µçÆ½·¢ÉúÌø±ä
 80   TIM_OC1Init(TIM3, &TIM_OCInitStructure);     //Ê¹ÄÜÍ¨µÀ1
 81   TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Disable);
 82
 83     //Ê¹ÄÜ±È½ÏÊä³ö·×ªÄ£Ê½Í¨µÀ2
 84   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
 85   TIM_OCInitStructure.TIM_Pulse = CCR2_Val;      //ÉèÖÃÍ¨µÀ2µÄµçÆ½Ìø±äÖµ£¬Êä³öÁíÍâÒ»¸öÕ¼¿Õ±ÈµÄPWM
 86   TIM_OC2Init(TIM3, &TIM_OCInitStructure);      //Ê¹ÄÜÍ¨µÀ2
 87   TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Disable);
 88
 89     //Ê¹ÄÜ±È½ÏÊä³ö·×ªÄ£Ê½Í¨µÀ3
 90     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
 91   TIM_OCInitStructure.TIM_Pulse = CCR3_Val;    //ÉèÖÃÍ¨µÀ3µÄµçÆ½Ìø±äÖµ£¬Êä³öÁíÍâÒ»¸öÕ¼¿Õ±ÈµÄPWM
 92   TIM_OC3Init(TIM3, &TIM_OCInitStructure);     //Ê¹ÄÜÍ¨µÀ3
 93     TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Disable);
 94
 95     //Ê¹ÄÜ±È½ÏÊä³ö·×ªÄ£Ê½Í¨µÀ4
 96   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
 97   TIM_OCInitStructure.TIM_Pulse = CCR4_Val;    //ÉèÖÃÍ¨µÀ4µÄµçÆ½Ìø±äÖµ£¬Êä³öÁíÍâÒ»¸öÕ¼¿Õ±ÈµÄPWM
 98   TIM_OC4Init(TIM3, &TIM_OCInitStructure);    //Ê¹ÄÜÍ¨µÀ4
 99   TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Disable);
100
101   TIM_ARRPreloadConfig(TIM3, ENABLE);             // Ê¹ÄÜTIM3ÖØÔØ¼Ä´æÆ÷ARR
102
103   /* TIM3 enable counter */
104   TIM_Cmd(TIM3, ENABLE);                   //Ê¹ÄÜ¶¨Ê±Æ÷3
105     TIM_ITConfig(TIM3, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);
106 }
107
108 /*********************************************************************
109   * @brief  Initialize the NCIC
110     * @param  None
111   * @retval None
112     * @date   20141205
113 ***********************************************************************/
114 void TIM_NVIC_Configuration(void)
115 {
116     NVIC_InitTypeDef NVIC_InitStructure;
117
118     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
119
120   NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
121   NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
122   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
123   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
124   NVIC_Init(&NVIC_InitStructure);
125 }
126
127
128 /*
129  * º¯ÊýÃû£ºTIM3_PWM_Init
130  * ÃèÊö  £ºTIM3 Êä³öPWMÐÅºÅ³õÊ¼»¯£¬Ö»Òªµ÷ÓÃÕâ¸öº¯Êý
131  *         TIM3µÄËÄ¸öÍ¨µÀ¾Í»áÓÐPWMÐÅºÅÊä³ö
132  * ÊäÈë  £ºÎÞ
133  * Êä³ö  £ºÎÞ
134  * µ÷ÓÃ  £ºÍâ²¿µ÷ÓÃ
135  */
136 void TIM3_PWM_Init(void)
137 {
138     TIM3_GPIO_Config();
139     TIM3_Mode_Config();
140     TIM_NVIC_Configuration();
141 }
142
143 /******************* (C) COPYRIGHT 2015 *****END OF FILE************/

TIM3中断里面更新CCRx的值：

 1 extern uint16_t CCR1_Val;
 2 extern uint16_t CCR2_Val;
 3 extern uint16_t CCR3_Val;
 4 extern uint16_t CCR4_Val;
 5 /******************************************************************************/
 6 /*                                                                            */
 7 /*             ¶¨Ê±Æ÷3ÖÐ¶Ï·þÎñ³ÌÐò                                            */
 8 /******************************************************************************/
 9 void TIM3_IRQHandler(void)
10 {
11     u16 capture;
12
13     if (TIM_GetITStatus(TIM3, TIM_IT_CC1) != RESET)  //¼ì²éTIM3¸üÐÂÖÐ¶Ï·¢ÉúÓë·ñ
14     {
15         TIM_ClearITPendingBit(TIM3, TIM_IT_CC1 );
16         capture = TIM_GetCapture1(TIM3);
17 //        capture = TIM_GetCounter(TIM3);
18         TIM_SetCompare1(TIM3, capture + CCR1_Val );
19     }
20
21     if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)  //¼ì²éTIM3¸üÐÂÖÐ¶Ï·¢ÉúÓë·ñ
22     {
23         TIM_ClearITPendingBit(TIM3, TIM_IT_CC2 );
24         capture = TIM_GetCapture2(TIM3);
25 //        capture = TIM_GetCounter(TIM3);
26         TIM_SetCompare2(TIM3, capture+CCR2_Val );
27     }
28
29     if (TIM_GetITStatus(TIM3, TIM_IT_CC3) != RESET)  //¼ì²éTIM3¸üÐÂÖÐ¶Ï·¢ÉúÓë·ñ
30     {
31         TIM_ClearITPendingBit(TIM3, TIM_IT_CC3 );
32         capture = TIM_GetCapture3(TIM3);
33 //        capture = TIM_GetCounter(TIM3);
34         TIM_SetCompare3(TIM3, capture + CCR3_Val );
35     }
36
37     if (TIM_GetITStatus(TIM3, TIM_IT_CC4) != RESET)  //¼ì²éTIM3¸üÐÂÖÐ¶Ï·¢ÉúÓë·ñ
38     {
39         TIM_ClearITPendingBit(TIM3, TIM_IT_CC4 );
40         capture = TIM_GetCapture4(TIM3);
41 //        capture = TIM_GetCounter(TIM3);
42         TIM_SetCompare4(TIM3, capture + CCR4_Val );
43     }
44
45 }

设置每个通道在输出比较匹配时产生中断，在中断中将比较寄存器的数值读出并加上新设置的数值，如果计算出的数值超过16位则舍弃超出的部分，再把这个新的数值写回相应的比较寄存器；这样下次比较成功将刚好发生在一个半波周期之后，对应的管脚将被翻转。

为什么还要加上上次的比较寄存器的值，这样岂不是每次的比较寄存器的值都不一样啊？直接设置最新的比较寄存器的值不行吗？当然不行，因为输出比较器比较的是当前的值与CNT的值，而不是比较的是CNT计数的个数。是绝对值，而不是相对值！计数器（CNT）的值一直是累加的，上面程序中设置的自动装载的值是65535，这样的目的是让计数器循环的进行累加，从而CCRx的值永远小于等于CNT,使输出比较寄存器匹配时，CNT的值不会是中间从0开始计数的，这样保证了方波占空比是固定的50%。当输出比较匹配时，进入中断，产生信号翻转，同时给CCRx赋新值，但是CNT此时有可能不是从0开始计数，所以必须把之前的CCRx中的值读出来。加上新设置的值然后再赋给CCRx。

时间： 2024-10-25 23:42:15

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