7路PWM产生程序阅读

拼搏现实的明天。 2022-07-13 08:41 207阅读 0赞

如下是7路PWM产生的程序解读，粘贴程序如下，并会在一些内容上做简单注释说明，以方便理解阅读，对于具体的产生原理需要阅读《STM32不完全手册》或是其它STM32的相关资料文档。使用库函数的方式完成功能实现，需要对库函数有一定的熟悉了解，相对于寄存器方式的方式更加快捷，但是对于初学者还是寄存器的方式更容易理解，加深学习效果。

程序的设计步骤为：

1、初始化系统时钟，使能相应的module的时钟；

2、GPIO的相应设置，使用GPIO的复用功能；

3、设置定时器的时基，采用的是内部时钟，主要设置频率、计数模式、分频倍频；

4、设置相应通道，包括比较寄存器的值、使能输出驱动、输出模式、输出极性、idle状态值

\#include "stm32f10x.h"

TIM\_TimeBaseInitTypeDef TIM\_TimeBaseStructure;

TIM\_OCInitTypeDef TIM\_OCInitStructure;

uint16\_t TimerPeriod = 0;

uint16\_t Channel1Pulse = 0, Channel2Pulse = 0, Channel3Pulse = 0, Channel4Pulse = 0;

/\* Private function prototypes -----------------------------------------------\*/

void RCC\_Configuration(void); // 关于设备的时钟初始化在rcc.c的库文件中，startup文件启动时自动跳转至时钟设置处，在如下文档中只是做相应的module的时钟使能

void GPIO\_Configuration(void); // 设置 channel的GPIO，需要复用功能开启

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\_stm32f10x\_xx.s) before to branch to application main.

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

system\_stm32f10x.c file

\*/

/\* System Clocks Configuration \*/

RCC\_Configuration();

/\* GPIO Configuration \*/

GPIO\_Configuration();

/\* TIM1 Configuration ---------------------------------------------------

Generate 7 PWM signals with 4 different duty cycles:

TIM1CLK = SystemCoreClock, Prescaler = 0, TIM1 counter clock = SystemCoreClock

SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density

and Connectivity line devices and to 24 MHz for Low-Density Value line and

Medium-Density Value line devices

The objective is to generate 7 PWM signal at 17.57 KHz:（72MHz/4097=17570Hz 所以反向计算定时器周期为如下公式）

\- TIM1\_Period = (SystemCoreClock / 17570) - 1

The channel 1 and channel 1N duty cycle is set to 50%

The channel 2 and channel 2N duty cycle is set to 37.5%

The channel 3 and channel 3N duty cycle is set to 25%

The channel 4 duty cycle is set to 12.5%

The Timer pulse is calculated as follows:

\- ChannelxPulse = DutyCycle \* (TIM1\_Period - 1) / 100

\----------------------------------------------------------------------- \*/

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

TimerPeriod = (SystemCoreClock / 17570 ) - 1;

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

Channel1Pulse = (uint16\_t) (((uint32\_t) 5 \* (TimerPeriod - 1)) / 10);

/\* Compute CCR2 value to generate a duty cycle at 37.5% for channel 2 and 2N \*/

Channel2Pulse = (uint16\_t) (((uint32\_t) 375 \* (TimerPeriod - 1)) / 1000);

/\* Compute CCR3 value to generate a duty cycle at 25% for channel 3 and 3N \*/

Channel3Pulse = (uint16\_t) (((uint32\_t) 25 \* (TimerPeriod - 1)) / 100);

/\* Compute CCR4 value to generate a duty cycle at 12.5% for channel 4 \*/

Channel4Pulse = (uint16\_t) (((uint32\_t) 125 \* (TimerPeriod- 1)) / 1000);

/\* Time Base configuration **时基的设置**\*/

TIM\_TimeBaseStructure.TIM\_Prescaler = 0;

TIM\_TimeBaseStructure.TIM\_CounterMode = TIM\_CounterMode\_Up;

TIM\_TimeBaseStructure.TIM\_Period = TimerPeriod;

TIM\_TimeBaseStructure.TIM\_ClockDivision = 0;

TIM\_TimeBaseStructure.TIM\_RepetitionCounter = 0;

TIM\_TimeBaseInit(TIM1, &TIM\_TimeBaseStructure);

/\* **Channel 1, 2,3 and 4 Configuration in PWM mode** \*/

TIM\_OCInitStructure.TIM\_OCMode = TIM\_OCMode\_PWM2;

TIM\_OCInitStructure.TIM\_OutputState = TIM\_OutputState\_Enable;

TIM\_OCInitStructure.TIM\_OutputNState = TIM\_OutputNState\_Enable;

TIM\_OCInitStructure.TIM\_Pulse = Channel1Pulse;

TIM\_OCInitStructure.TIM\_OCPolarity = TIM\_OCPolarity\_Low;

TIM\_OCInitStructure.TIM\_OCNPolarity = TIM\_OCNPolarity\_High;

TIM\_OCInitStructure.TIM\_OCIdleState = TIM\_OCIdleState\_Set;

TIM\_OCInitStructure.TIM\_OCNIdleState = TIM\_OCIdleState\_Reset;

TIM\_OC1Init(TIM1, &TIM\_OCInitStructure);

TIM\_OCInitStructure.TIM\_Pulse = Channel2Pulse;

TIM\_OC2Init(TIM1, &TIM\_OCInitStructure);

TIM\_OCInitStructure.TIM\_Pulse = Channel3Pulse;

TIM\_OC3Init(TIM1, &TIM\_OCInitStructure);

TIM\_OCInitStructure.TIM\_Pulse = Channel4Pulse;

TIM\_OC4Init(TIM1, &TIM\_OCInitStructure);

/\* TIM1 counter enable \*/

TIM\_Cmd(TIM1, ENABLE);

/\* TIM1 Main Output Enable \*/

TIM\_CtrlPWMOutputs(TIM1, ENABLE);

while (1)

\{\}

**// 使能相应模块的时钟**

void RCC\_Configuration(void)

/\* TIM1, GPIOA, GPIOB, GPIOE and AFIO clocks enable \*/

RCC\_APB2PeriphClockCmd(RCC\_APB2Periph\_TIM1 | RCC\_APB2Periph\_GPIOA | RCC\_APB2Periph\_GPIOE|

RCC\_APB2Periph\_GPIOB |RCC\_APB2Periph\_AFIO, ENABLE);

/**/子函数为相应的GPIO的设置**

void GPIO\_Configuration(void)

GPIO\_InitTypeDef GPIO\_InitStructure;

/\* GPIOA Configuration: Channel 1, 2 and 3 as alternate function push-pull \*/

GPIO\_InitStructure.GPIO\_Pin = GPIO\_Pin\_8 | GPIO\_Pin\_9 | GPIO\_Pin\_10 | GPIO\_Pin\_11;

GPIO\_InitStructure.GPIO\_Mode = GPIO\_Mode\_AF\_PP;

GPIO\_InitStructure.GPIO\_Speed = GPIO\_Speed\_50MHz;

GPIO\_Init(GPIOA, &GPIO\_InitStructure);

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

GPIO\_InitStructure.GPIO\_Pin = GPIO\_Pin\_13 | GPIO\_Pin\_14 | GPIO\_Pin\_15;

GPIO\_Init(GPIOB, &GPIO\_InitStructure);

如下是示波器量测的波形，channel 2 GPIOA 的Pin 9

从图中可以看出信号是正确的，频率17.57KHz，占空比为37.5%

7路PWM产生程序阅读

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