所以我有这个项目。当紧急车辆接近红绿灯时，系统将优先考虑紧急车辆，当他们靠近时，我想将红绿灯的状态从红色变为绿色，但顺序正确。
我已经设法将其关闭，但它不适用于真正的汽车，因为xbees（车辆上的协调器和自制交通信号灯上的终端设备）需要一段时间来进行通信，这对于车辆的速度来说是不够的接近红绿灯，让我们说平均速度为60公里/小时。
系统的工作原理如下。车上有一个arduino，上面有一个GPS盾牌和一个xbee设置为COORDINATOR。在arduino上的程序中，它会检查gps是否读取保存在arduino中的坐标，以便检查实时坐标，如果它们匹配，则xbee会将消息发送到设置为终端设备的相应xbees再次设置的交通信号灯是arduino + xbee。
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，我使用他们的代码和我的一些代码。
// 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if（GPS.fix（））及以后的地方。
以下是交通灯模拟的草图，如果它收到消息＆＃34; K＆＃34;它将保持绿灯，直到它不再接收它。
#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：当它收到来自附近arduino的消息时，如何在交通信号灯完成该循环之前将红绿灯改为绿色时，如何立即中断红绿灯模拟？因为在一个真实的例子中，绿灯和红灯会说超过20秒。
问题：xbees上更快的波特率能否实现更快的xbee通信？
提前谢谢
答案 0 :(得分：1)
您需要更改红绿灯模拟中的loop()。有一个变量用于存储＆＃34;状态＆＃34;光线，以及计时器，以跟踪下一次状态变化发生的时间。这样，你的循环也可以每次检查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.
}
这仅仅涵盖了基础知识，但它显示了loop()函数设计的一个重要方面 - 它应该永远不会运行超过几毫秒。不要在主循环内部发生延迟，跟踪设备的状态，然后使用逻辑来确定状态是否需要在循环的传递中更改。
此外，尽可能使用更高的波特率，以避免串行传输的延迟，摆脱循环中的700ms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?
}
}