红绿灯模拟和xbee通信

Question

所以我有这个项目。当紧急车辆接近红绿灯时，系统将优先处理紧急车辆，当他们接近时，我想将红绿灯的状态从红色变为绿色，但顺序正确。

我已经成功完成了，但它不适用于真车，因为 xbees（车辆上的协调器和自制红绿灯上的终端设备）需要一些时间进行通信，这对于车辆的速度来说是不够的以平均 60 公里/小时的速度接近红绿灯。

系统是这样工作的。车辆上有一个 arduino，上面有一个 GPS 防护罩和一个设置为 COORDINATOR 的 xbee。在 arduino 上的程序中，它检查 gps 是否读取保存在 arduino 内的坐标，以便检查实时坐标，如果它们匹配，xbee 将向设置为终端设备的相应 xbee 发送消息在再次设置为 arduino + xbee 的红绿灯上。

问题 1 是我需要在 xbees (COORDINATOR - END DEVICE) 之间建立更快的连接

这是 ARDUINO-GPS-COORDINATOR 的 arduino 草图。注意：GPS Shield 来自 adafruit，我使用他们的代码加上我的一些代码。

// Test code for Adafruit GPS modules using MTK3329/MTK3339 driver
//
// This code shows how to listen to the GPS module in an interrupt
// which allows the program to have more 'freedom' - just parse
// when a new NMEA sentence is available! Then access data when
// desired.
//
// Tested and works great with the Adafruit Ultimate GPS module
// using MTK33x9 chipset
//    ------> http://www.adafruit.com/products/746
// Pick one up today at the Adafruit electronics shop 
// and help support open source hardware & software! -ada

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11);
SoftwareSerial xbee(13,12);

// If using hardware serial (e.g. Arduino Mega), comment out the
// above SoftwareSerial line, and enable this line instead
// (you can change the Serial number to match your wiring):

//HardwareSerial mySerial = Serial1;


Adafruit_GPS GPS(&mySerial);


// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences. 
#define GPSECHO  true

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;
void useInterrupt(boolean); // Func prototype keeps Arduino 0023 happy

void setup()  
{

  Serial.begin(115200);
  Serial.println("Adafruit GPS library basic test!");
  xbee.begin(9600);
  xbee.println("SoftwareSerial on coordinator working!");
  GPS.begin(9600);

  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  // uncomment this line to turn on only the "minimum recommended" data
  //GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time

  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  // Request updates on antenna status, comment out to keep quiet
  GPS.sendCommand(PGCMD_ANTENNA);

  // the nice thing about this code is you can have a timer0 interrupt go off
  // every 1 millisecond, and read data from the GPS for you. that makes the
  // loop code a heck of a lot easier!
  useInterrupt(true);

  delay(1000);
  // Ask for firmware version
  mySerial.println(PMTK_Q_RELEASE);
}


// Interrupt is called once a millisecond, looks for any new GPS data, and stores it
SIGNAL(TIMER0_COMPA_vect) {
  char c = GPS.read();
  // if you want to debug, this is a good time to do it!
#ifdef UDR0
  if (GPSECHO)
    if (c) UDR0 = c;  
    // writing direct to UDR0 is much much faster than Serial.print 
    // but only one character can be written at a time. 
#endif
}

void useInterrupt(boolean v) {
  if (v) {
    // Timer0 is already used for millis() - we'll just interrupt somewhere
    // in the middle and call the "Compare A" function above
    OCR0A = 0xAF;
    TIMSK0 |= _BV(OCIE0A);
    usingInterrupt = true;
  } else {
    // do not call the interrupt function COMPA anymore
    TIMSK0 &= ~_BV(OCIE0A);
    usingInterrupt = false;
  }
}

// difference_ratio
float diff_ratio = 0.010;

// COORDINATES INDEX
float coord_lat = 23;
float coord_lon = 23;

uint32_t timer = millis();
void loop()                     // run over and over again
{
  // in case you are not using the interrupt above, you'll
  // need to 'hand query' the GPS, not suggested :(
  if (! usingInterrupt) {
    // read data from the GPS in the 'main loop'
    char c = GPS.read();
    // if you want to debug, this is a good time to do it!
    if (GPSECHO)
      if (c) Serial.print(c);
  }

  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences! 
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false

    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another
  }

  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // approximately every 2 seconds or so, print out the current stats
  if (millis() - timer > 2000) { 
    timer = millis(); // reset the timer

    Serial.print("\nTime: ");
    Serial.print(GPS.hour, DEC); Serial.print(':');
    Serial.print(GPS.minute, DEC); Serial.print(':');
    Serial.print(GPS.seconds, DEC); Serial.print('.');
    Serial.println(GPS.milliseconds);
    Serial.print("Date: ");
    Serial.print(GPS.day, DEC); Serial.print('/');
    Serial.print(GPS.month, DEC); Serial.print("/20");
    Serial.println(GPS.year, DEC);
    Serial.print("Fix: "); Serial.print((int)GPS.fix);
    Serial.print(" quality: "); Serial.println((int)GPS.fixquality); 


    if (GPS.fix) {
      //Serial.print("Location: ");
      //Serial.print(GPS.latitude, 4); Serial.print(GPS.lat);
      //Serial.print(", "); 
      //Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
      Serial.print("Location (in degrees, works with Google Maps): ");
      Serial.print(GPS.latitudeDegrees, 4);
      Serial.print(", "); 
      Serial.println(GPS.longitudeDegrees, 4);

      //Serial.print("Speed (knots): "); Serial.println(GPS.speed);
      //Serial.print("Angle: "); Serial.println(GPS.angle);
      //Serial.print("Altitude: "); Serial.println(GPS.altitude);
      //Serial.print("Satellites: "); Serial.println((int)GPS.satellites);
      if(GPS.latitudeDegrees + diff_ratio >= coord_lat && coord_lat >= GPS.latitudeDegrees - diff_ratio) {
         if(GPS.longitudeDegrees + diff_ratio >= coord_lon && coord_lon >= GPS.longitudeDegrees - diff_ratio){
            Serial.println("location OKAY");
            xbee.println("K");
         }
      }

      //if((float)GPS.latitude > (home_lat - diff_ratio) && (float)
    }
  }
}

重要的部分是它说 if(GPS.fix()) 和稍后的地方。

这是交通灯模拟的草图，如果它收到消息“K”，它将一直保持绿灯，直到不再收到它为止。

#include <SoftwareSerial.h>

SoftwareSerial xbee(3,2);

int greenled = 8; //Led's and pins
int yellowled = 9;
int redled = 10;
int ard_led = 13;

void setup(){
  pinMode(greenled,OUTPUT);
  pinMode(yellowled, OUTPUT);
  pinMode(redled, OUTPUT);
  pinMode(ard_led,OUTPUT);

  Serial.begin(9600);
  xbee.begin(9600);
}

void loop(){

      delay(700);

      if(xbee.available() > 0 && xbee.read() == 'K' && digitalRead(ard_led) == 0){

        //Serial.println("second block");
        digitalWrite(redled,HIGH);
        delay(1000);
        digitalWrite(yellowled, HIGH); //Yellow and red on for 2 seconds
        digitalWrite(ard_led,HIGH);

      }else if(xbee.available() > 0 && xbee.read() == 'K' && digitalRead(ard_led) == 1){
         //Serial.println("third block");
         blinking_green();

      }

      else if(!xbee.available() && xbee.read() != 'K' && digitalRead(greenled) == 0){
        //Serial.println("first block");
        digitalWrite(redled, HIGH);
        delay(1000);
        digitalWrite(yellowled, HIGH); //Yellow and red on for 2 seconds
        delay(1000);
        digitalWrite(redled, LOW); //Red and Yellow off
        digitalWrite(yellowled, LOW);
        digitalWrite(greenled, HIGH); //Green on for 5 seconds
        delay(3000);
        digitalWrite(greenled, LOW); //Green off, yellow on for 2 seconds      
        digitalWrite(yellowled, HIGH);
        delay(1000);
        digitalWrite(yellowled,LOW);
        digitalWrite(redled,HIGH);


      } else if(!xbee.available() && xbee.read() != 'K' && digitalRead(greenled) == 1 && digitalRead(yellowled == 0)){
          //Serial.println("fourth block");
          digitalWrite(greenled,LOW);
          digitalWrite(yellowled, HIGH);
          delay(1000);
          digitalWrite(yellowled, LOW);
          digitalWrite(redled,HIGH);
          digitalWrite(ard_led,LOW);
        }

}

void blinking_green(){
    digitalWrite(redled, LOW); //Red and Yellow off
    digitalWrite(yellowled, LOW);
    digitalWrite(greenled,HIGH);
    delay(2500);


}

问题 2：当交通灯模拟从附近的 arduino 收到消息以在完成该循环之前将交通灯更改为绿色时，我如何立即中断交通灯模拟？因为在一个真实的例子中，绿灯和红灯会持续超过 20 秒。

问题：xbee 上更快的波特率能否实现更快的 xbee 通信？

提前谢谢你

Answer 1

您需要更改交通灯模拟上的loop()。有一个变量用于存储灯的“状态”，还有一个计时器来跟踪下一次状态更改发生的时间。这样，您的循环也可以每次都检查 XBee 串行输入。

if (xbee_event_happened()) {
    set_leds_off();
    timer = millis();
    state = STATE_FLASH_GREEN_OFF;
}
switch (state) {
    case STATE_FLASH_GREEN_OFF:
        if (millis() - timer > 1000) {
            set_leds_green();
            state = STATE_FLASH_GREEN_ON;
            timer = millis();
        }
        break;
    case STATE_FLASH_GREEN_ON:
        if (millis() - timer > 1000) {
            set_leds_off();
            state = STATE_FLASH_GREEN_OFF;
            timer = millis();
        }
        break;
    case STATE_RED:
        if (millis() - timer > 5000) {
            set_leds_green();
            state = STATE_GREEN;
            timer = millis();
        }
        break;
    case STATE_GREEN:
        if (millis() - timer > 3000) {
            set_leds_yellow();
            state = STATE_YELLOW;
            timer = millis();
        }
        break;
    // etc.
}

这仅涵盖基础知识，但它展示了loop() 函数设计的一个重要方面——它的运行时间不应超过几毫秒。在主循环中不要有延迟，跟踪设备的状态，然后使用逻辑来决定状态是否需要在循环的那次循环中改变。

此外，尽可能使用更高的波特率以避免串行传输的延迟，消除循环中 700 毫秒的延迟，并更好地组织 if/else 结构：

  if (xbee.available() > 0) {
    character = xbee.read();
    if (character == 'K') {
       if (digitalRead(ard_led)) {
         // second block
       } else {
         // third block
       }
    } else if (character == 'X') {
       // do something different?  Vehicle left area?
    }
  }