Arduino for STM32

Code: Select all

void Request()      /* Microcontroller send request */
{

  uint16_t PulseLOW = 20000; // should > 18ms
  uint16_t PulseHIGH = 18000; // not important
  
  pinMode(DHT11, PWM);

  Timer2.pause(); // stop the timers before configuring them
  timer_oc_set_mode(TIMER2, 1, TIMER_OC_MODE_PWM_2, TIMER_OC_PE);//set PWM Mode2,and enable
  Timer2.setPrescaleFactor(72); // 1 microsecond resolution
  Timer2.setOverflow(PulseLOW + PulseHIGH-1);
  Timer2.setCompare(TIMER_CH1, PulseLOW);
 // Triggered after PulseLOW
  Timer2.attachInterrupt(TIMER_CH1,Response);
  
  // counter setup in one pulse mode
  TIMER2_BASE->CR1 = ( TIMER_CR1_OPM ); // one pulse mode
  
  // as slave triggered by External input for Timer 2,
  //I don't quite understand this sentence and commented it
  //TIMER2_BASE->SMCR = ( TIMER_SMCR_TS_ETRF | TIMER_SMCR_SMS_TRIGGER );
  
  TIMER2_BASE->CCER =  TIMER_CCER_CC1E ; // enable channels 1 
  
  Timer2.refresh(); // start timer 2
  Timer2.resume(); // let timer 2 run

/*
                    Using PWM Mode 2,but not work

  _______20MS__________-------------------18MS-------------------___________
  ^                    ^                                         ^
  |<----PulseLOW------>|<-- PulseHIGH, but don't need attention->|      
                       ^
                       |
                       
              Compare1Interrupt
              execution Response(),
           Change the mode of the Timer2

 */

}
 

void Response()
{
/*Change the mode of the Timer2*/
}

Code: Select all

/*
  The code for getting the timer and channel number for a pin is from the All-in-one setPWM example
  https://github.com/stm32duino/STM32Examples/blob/main/examples/Peripherals/HardwareTimer/All-in-one_setPWM/All-in-one_setPWM.ino .
*/

/*
  pwmpin must have HardwareTimer capability
*/

#define pwmpin  D3    // aka DHT11  external pullup on this pin


HardwareTimer *MyTim;
uint32_t channel;

void Response()
{
  MyTim->pauseChannel(channel);
 /* ... */
}

void setup()
{
  Serial.begin(115200);
  Serial.println("setup()");
  
  pinMode(pwmpin,INPUT);        // without this, pwmpin was observed to be low before timer was resumed.
 
  // Automatically retrieve TIM instance and channel associated to pwmpin
  // This is used to be compatible with all STM32 series automatically.
  TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pwmpin), PinMap_PWM);
  channel = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pwmpin), PinMap_PWM));
 
  // Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup() function is finished.
  MyTim = new HardwareTimer(Instance);

  Serial.print(digitalRead(pwmpin));   // check that pwmpin is high or pulled up before timer enabled
  
  MyTim->setMode(channel, TIMER_OUTPUT_COMPARE_PWM2, pwmpin);
  MyTim->setOverflow(40*1000, MICROSEC_FORMAT);
  MyTim->setCaptureCompare(channel, 20*1000, MICROSEC_COMPARE_FORMAT);
  MyTim->refresh();
  MyTim->attachInterrupt(channel, Response);
  MyTim->resume();
  //TIM_HandleTypeDef *MyTimHandle = MyTim->getHandle();
  //MyTimHandle->Instance->CR1 |= TIM_CR1_OPM;   // not actually necessary to use one pulse mode 
  
  for ( int i=0; i<90; i++) { delay(1); Serial.print(digitalRead(pwmpin));}
  Serial.println(" "); 

  // Produces output like this. Trigger or starting point is just before the timer is started.
  // PWM2 mode without setting OPM, and without Response() routine attached:
  // 1000000000000000000001111111111111111111100000000000000000000111111111111111111110000...
  // PWM2 mode, setting OPM, but still without Response() routine attached:
  // 1000000000000000000001111111111111111111100000000000000000000000000000000000000000000...
  // PWM2 mode, with or without setting OPM, but with channel callback Response() routine doing MyTim->pauseChannel(channel):
  // 1000000000000000000001111111111111111111111111111111111111111111111111111111111111111...
  // ( with no sensor attached, so of course, no response )
  
}


void loop()
{
  // nothing to see here folks
}

Code: Select all

int32_t channel_1_start, channel_1_stop, channel_1,a=0,b=0,c=0;
//This will also work
int32_t channel_1_start, channel_1_stop, channel_1;
int32_t  a=0,b=0,c=0;
//This will still work as well
int32_t channel_1_start, channel_1_stop, channel_1;
int32_t d=0,e=0,f=0;


void loop(){
};

//*********Even put it here，it still work as well
int32_t d=0,e=0,f=0;

void Request(){
};
void Response(){
};
void handler_channel_1(){
};

Code: Select all

//This will not work
int32_t channel_1_start, channel_1_stop, channel_1; //delete abc variable
//This will still not 
int32_t a=0,b=0,c=0;//delete channel variable
//It seems that it will only work if the number of variables is greater than a value

void loop(){
};
void Request(){
};

void Response(){
};
void handler_channel_1(){
};