STM32使用定时器在普通gpio上模拟pwm-红牛开发板LED1的亮度调节

stm32F103zet只有固定的几个针脚可以输出tim定时器信号，在不支持tim输出的口上就没法输出pwm，在红牛开发版上的表现就是控制lcd屏幕亮度的a1针脚，可以输出pwm，屏幕亮度可以无极调节，但是4个led灯就只能控制开关。使用arduino的analogWrite函数，只能调节开关。

可以用定时器的中断来控制普通io口的开关，达到模拟pwm调制的结果。参考这文章  STM32普通io口模拟pwm输出的三种方法_普通io口模拟输出pwm-CSDN博客

这里使用第一个办法。使用的是arduino的库  STM32TimerInterrupt，避免了对tim结构体的复杂操作。使用的是红牛开发板

/****************************************************************************************************************************
  TimerInterruptLEDDemo.ino
  For STM32 boards
  Written by Khoi Hoang
  
  Built by Khoi Hoang https://github.com/khoih-prog/STM32_TimerInterrupt
  Licensed under MIT license
  
  Now even you use all these new 16 ISR-based timers,with their maximum interval practically unlimited (limited only by
  unsigned long miliseconds), you just consume only one STM32 timer and avoid conflicting with other cores' tasks.
  The accuracy is nearly perfect compared to software timers. The most important feature is they're ISR-based timers
  Therefore, their executions are not blocked by bad-behaving functions / tasks.
  This important feature is absolutely necessary for mission-critical tasks.
*****************************************************************************************************************************/

/*
   Notes:
   Special design is necessary to share data between interrupt code and the rest of your program.
   Variables usually need to be "volatile" types. Volatile tells the compiler to avoid optimizations that assume
   variable can not spontaneously change. Because your function may change variables while your program is using them,
   the compiler needs this hint. But volatile alone is often not enough.
   When accessing shared variables, usually interrupts must be disabled. Even with volatile,
   if the interrupt changes a multi-byte variable between a sequence of instructions, it can be read incorrectly.
   If your data is multiple variables, such as an array and a count, usually interrupts need to be disabled
   or the entire sequence of your code which accesses the data.
*/

#if !( defined(STM32F0) || defined(STM32F1) || defined(STM32F2) || defined(STM32F3)  ||defined(STM32F4) || defined(STM32F7) || \
       defined(STM32L0) || defined(STM32L1) || defined(STM32L4) || defined(STM32H7)  ||defined(STM32G0) || defined(STM32G4) || \
       defined(STM32WB) || defined(STM32MP1) || defined(STM32L5) )
  #error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting.
#endif

// These define's must be placed at the beginning before #include "STM32TimerInterrupt.h"
// _TIMERINTERRUPT_LOGLEVEL_ from 0 to 4
// Don't define _TIMERINTERRUPT_LOGLEVEL_ > 0. Only for special ISR debugging only. Can hang the system.
// Don't define TIMER_INTERRUPT_DEBUG > 2. Only for special ISR debugging only. Can hang the system.
#define TIMER_INTERRUPT_DEBUG         1
#define _TIMERINTERRUPT_LOGLEVEL_     4

#include "STM32TimerInterrupt.h"

// #ifndef LED_BUILTIN
  #define LED_BUILTIN       PF6               // Pin 33/PB0 control on-board LED_GREEN on F767ZI
// #endif

#ifndef LED_BLUE
  #define LED_BLUE          PF7               // Pin 73/PB7 control on-board LED_BLUE on F767ZI
#endif

#ifndef LED_RED
  #define LED_RED           PF8             // Pin 74/PB14 control on-board LED_BLUE on F767ZI
#endif
   
#include "STM32TimerInterrupt.h"
#include "STM32_ISR_Timer.h"

#define TIMER_INTERVAL_MS         100
#define HW_TIMER_INTERVAL_MS      50

// Depending on the board, you can select STM32 Hardware Timer from TIM1-TIM22
// For example, F767ZI can select Timer from TIM1-TIM14
// If you select a Timer not correctly, you'll get a message from ci[ompiler
// 'TIMxx' was not declared in this scope; did you mean 'TIMyy'? 

// Init STM32 timer TIM1
STM32Timer ITimer(TIM1);

// Init STM32_ISR_Timer
// Each STM32_ISR_Timer can service 16 different ISR-based timers
STM32_ISR_Timer ISR_Timer;

#define TIMER_INTERVAL_0_5S           500L
#define TIMER_INTERVAL_1S             1000L
#define TIMER_INTERVAL_1_5S           1500L

void TimerHandler()
{
  ISR_Timer.run();
}

// In STM32, avoid doing something fancy in ISR, for example complex Serial.print with String() argument
// The pure simple Serial.prints here are just for demonstration and testing. Must be eliminate in working environment
// Or you can get this run-time error / crash
unsigned int count=0;
unsigned int  i = 1;//i就是占空比
void doingSomething1()
{
  count++;//计中断次数
  if(count%100<i)//i：占空比值，
        digitalWrite(LED_BUILTIN, 1);//高电平
        
        else
        digitalWrite(LED_BUILTIN, 0);//高电平;
  //digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
  
}

void doingSomething2()
{
  digitalWrite(LED_BLUE, !digitalRead(LED_BLUE));
}
void doingSomething3()
{
  digitalWrite(LED_RED, !digitalRead(LED_RED));
}

void setup()
{
  Serial.begin(115200);
  while (!Serial);

  delay(100);

  Serial.print(F("\nStarting TimerInterruptLEDDemo on ")); Serial.println(BOARD_NAME);
  Serial.println(STM32_TIMER_INTERRUPT_VERSION);
  Serial.print(F("CPU Frequency = ")); Serial.print(F_CPU / 1000000); Serial.println(F(" MHz"));

  // Instantiate HardwareTimer object. Thanks to 'new' instanciation, HardwareTimer is not destructed when setup() function is finished.
  //HardwareTimer *MyTim = new HardwareTimer(Instance);

  // configure pin in output mode
  pinMode(LED_BUILTIN,  OUTPUT);
  pinMode(LED_BLUE,     OUTPUT);
  pinMode(LED_RED,      OUTPUT);

  // Interval in microsecs
  if (ITimer.attachInterruptInterval(HW_TIMER_INTERVAL_MS*1000 , TimerHandler))//过小的HW_TIMER_INTERVAL_MS会导致loop无法运行，这里测试过不需要调节
  {
    Serial.print(F("Starting ITimer OK, millis() = ")); Serial.println(millis());
  }
  else
    Serial.println(F("Can't set ITimer. Select another freq. or timer"));

  // Just to demonstrate, don't use too many ISR Timers if not absolutely necessary
  // You can use up to 16 timer for each ISR_Timer
  //ISR_Timer.setInterval(1000,  doingSomething1);
  ITimer.setFrequency(100000,  doingSomething1);//实测200k频率可以运行，300k不行，使用这个函数可以突破1ms的间隔限制
  ISR_Timer.setInterval(TIMER_INTERVAL_1S,    doingSomething2);
  ISR_Timer.setInterval(TIMER_INTERVAL_1_5S,  doingSomething3);
  
}


void loop()
{
  /* Nothing to do all is done by hardware. Even no interrupt required. */

  i++;
  //Serial.println(count);
  Serial.println(i);
  delay(40);
  if(i == 100)
  {
    
    i = 0;
    
  }//循环调节占空比，用来演示灯亮度变化


  
  
}