计时器超时后如何在LCD显示屏上显示“事故警报”

时间：2019-04-05 01:26:19

标签： c++ arduino lcd

我正在制作一个简单的程序，该程序可以循环运行交通信号灯，并具有超声波传感器和16x2 LCD。概念是，如果超声波读取的距离值等于或小于预设值，则表示正在检测交叉路口中的障碍物，并启动计时器。当计时器到期时，LCD显示屏发出警报。但是，如果在计时器启用时距离值超过预设值，它将停止。对于交通信号灯循环，我正在使用标准的Arduino``延迟''功能，例如delay（3000）;。我遇到的问题是，一旦计时器结束，LCD不会显示任何内容。对于程序中的警报计时器，我正在使用一个名为millisDelay的库。该库允许计时器运行而无需停止程序。

我尝试使用millisDelay库来运行交通信号灯，而不是标准延迟功能。但这不起作用，因为它会使交通信号灯处于恒定的循环中。

使用的库：

millisDelay.h和liquidCrystal.h 

#include <millisDelay.h>
#include <LiquidCrystal.h>

int red = 22;
int yellow = 23;
int green = 24;
int red2 = 25;
int yellow2 = 26;
int green2 = 27;
const int pingPin = 7; // Trigger Pin of Ultrasonic Sensor
const int echoPin = 6; // Echo Pin of Ultrasonic Sensor
long duration, inches, cm;
millisDelay alertdelay;
millisDelay ledDelay;

const int rs = 36, en = 38, d4 = 40, d5 = 42, d6 = 44, d7 = 46;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  // put your setup code here, to run once:
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(red2, OUTPUT);
  pinMode(yellow2, OUTPUT);
  pinMode(green2, OUTPUT);
  pinMode(pingPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600); // Starting Serial Terminal
}

void loop() {
  lcd.clear();
  lcd.begin(16,2);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  cm = microsecondsToCentimeters(duration);
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  delay(100);

  if (cm>=11){
    lcd.setCursor(0,0);
    lcd.print("Intersection");
    lcd.setCursor(0, 1);
    lcd.print("Clear");
  }

  else if (cm<7){
    lcd.setCursor(0,0);
    lcd.print("Intersection");
    lcd.setCursor(0, 1);
    lcd.print("Clear");
    alertdelay.start(7000);
    Serial.println("delay started");
  }

  if (alertdelay.isFinished()) {
    Serial.println("There is a crash up ahead");
    lcd.setCursor(0,0);
    lcd.print("Crash Up Ahead");
    lcd.setCursor(0,1);
    lcd.print("Use Caution");
  }

  delay(1000);
  //'2'refers to intersection number 2
  //green off,red2 on, yellow on for 3 seconds
  digitalWrite(red2, HIGH);
  digitalWrite(green, LOW);
  digitalWrite(yellow, HIGH);
  delay(3000);
  // turn off yellow1, then turn red on for 3 seconds
  digitalWrite(yellow, LOW);
  digitalWrite(red, HIGH);
  delay(3000);

  //after 3 seconds keep red 1 on and turn red2 off and green2 on,
  //green2 stays on for 15 seconds to let traffic through
  digitalWrite(red2, LOW);
  digitalWrite(green2, HIGH);
  delay(15000);
  //after 15 seconds green2 turns off, yellow 2 turns on
  //yellow2 turns on for 3 seconds,
  digitalWrite(green2, LOW);
  digitalWrite(yellow2, HIGH);
  delay(3000);
  //after 3 seconds, yellow2 turns off, and red 2 turns on
  digitalWrite(yellow2, LOW);
  digitalWrite(red2, HIGH);
  delay(3000);
  //3 seconds after red2 turns on, red 1 turns off and
  //green 1 turns on for 3 seconds
  //red2 stays on
  digitalWrite(red, LOW);
  digitalWrite(green, HIGH);
  delay(14000);
}

long microsecondsToCentimeters(long microseconds) {
  return microseconds / 29 / 2;
}

1 个答案:

答案 0 :(得分：0)

这些是您所做的事情。

1）您编写的代码需要42秒才能遍历循环。因此，您检查一下AlertDelay是否每42秒完成一次。 2）代码第二次到达循环的开头，您首先要在检查它是否正在运行或完成之前再次设置alertDelay，从而将其重置，因此，您的代码将永远不会到达该位置它显示崩溃。

这就是我要做的事情

#include <LiquidCrystal.h>

int red = 22;
int yellow = 23;
int green = 24;
int red2 = 25;
int yellow2 = 26;
int green2 = 27;
const int pingPin = 7; // Trigger Pin of Ultrasonic Sensor
const int echoPin = 6; // Echo Pin of Ultrasonic Sensor
long duration, inches, cm;

long alertDisplayTime = millis(), nextLedSwitchTime = millis();
bool displayAlert = false;

int switch_number=-1;

const int rs = 36, en = 38, d4 = 40, d5 = 42, d6 = 44, d7 = 46;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  // put your setup code here, to run once:
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(red2, OUTPUT);
  pinMode(yellow2, OUTPUT);
  pinMode(green2, OUTPUT);
  pinMode(pingPin, OUTPUT);
  pinMode(echoPin, INPUT);
  lcd.begin(16,2);
  Serial.begin(9600); // Starting Serial Terminal
  nextLedSwitchTime=1000+millis();
}

void loop() {
  lcd.clear();

  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(pingPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  cm = microsecondsToCentimeters(duration);
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  delay(100);

  if (cm>=11){
    lcd.setCursor(0,0);
    lcd.print("Intersection");
     lcd.setCursor(0, 1);
     lcd.print("Clear");
    displayAlert=false;
  }

  else if ((cm<7)&&(!displayAlert)){
    lcd.setCursor(0,0);
    lcd.print("Intersection");
    lcd.setCursor(0, 1);
    lcd.print("Clear");
    alertDisplayTime = millis()+7000;
    displayAlert=true;
    Serial.println("delay started");
  }

  if ((displayAlert==true)&&(alertDisplayTime<millis())) {
    Serial.println("There is a crash up ahead");
    lcd.setCursor(0,0);
    lcd.print("Crash Up Ahead");
    lcd.setCursor(0,1);
    lcd.print("Use Caution");
    displayAlert=false;
  }
  if(nextLedSwitchTime>=millis()){
    return;
  }
  long delay_time=0;
  switch_number++;
  switch(switch_number){
    case 0:
  //'2'refers to intersection number 2
  //green off,red2 on, yellow on for 3 seconds
  digitalWrite(red2, HIGH);
  digitalWrite(green, LOW);
  digitalWrite(yellow, HIGH);
  delay_time=3000;
  break;
    case 1:
  // turn off yellow1, then turn red on for 3 seconds
  digitalWrite(yellow, LOW);
  digitalWrite(red, HIGH);
  delay_time=3000;
  //after 3 seconds keep red 1 on and turn red2 off and green2 on,
  break;
    case 2:
  //green2 stays on for 15 seconds to let traffic through
  digitalWrite(red2, LOW);
  digitalWrite(green2, HIGH);
  //after 15 seconds green2 turns off, yellow 2 turns on
  delay_time=15000;
  break;
    case 3:
  //yellow2 turns on for 3 seconds,
  digitalWrite(green2, LOW);
  digitalWrite(yellow2, HIGH);
  //after 3 seconds, yellow2 turns off, and red 2 turns on
  delay_time=3000;
  break;
    case 4:
  digitalWrite(yellow2, LOW);
  digitalWrite(red2, HIGH);
  //3 seconds after red2 turns on, red 1 turns off and
  delay_time=3000;
  break;
    case 5:
  //green 1 turns on for 3 seconds
  //red2 stays on
  digitalWrite(red, LOW);
  digitalWrite(green, HIGH);
  delay_time = 14000;
    switch_number=-1;
  }
  nextLedSwitchTime = millis()+delay_time;
}

long microsecondsToCentimeters(long microseconds) {
  return microseconds / 29 / 2;
}

此代码的作用是它永远不会阻塞循环功能，因此几乎每秒钟执行一次函数检查以及崩溃检查。 另外，我设置了一个位，告诉代码警报延迟已经开始，这可以确保您的代码不会将其重置。

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