Air To Ground Display: Drone Mounted Ground Visible Display

//This code receives settings from the Particle cloud 
//It relays text received onto Serial 1 
//it also controls the position and optionally the sweep of a servo.
// this code oruns on a particle Boron, Electron or Photon device

//connect a servo to pin D0 
//connect whatever is listening for the text to pin TX1 at baud 115200

// follow all the instructions on the Particle website to setup your particle device
//Note: the below will only run if the particle device is connected to the internet, this is a feature of Particle devices where System mode set to the default  automatic

// Written by : Jasper Pons in 2020 for the NXP hovergames competition.


#include "Particle.h" 


//----------------- servo sweep variables------------
Servo myservo;  // create servo object to control a servo

   int bSweep = true;
   int pos;
   bool bgoingup;
   long ilastsweep;
   int servomax = 90;
   int servomin = 30;
   	
void setup() {
	Serial.begin(115200);
	Serial1.begin(115200);
	  
	  myservo.attach(D0);  // attaches the servo on the D6 pin to the servo object

// particle functions - these allow you to adjust variables using the particle console

	Particle.function("sendText", sendText);
	Particle.function("ServoPos", ServoPos);
	Particle.function("SetSweepInterval", SetSweepInterval);
	
		Particle.function("setservomax", setservomax);
		Particle.function("setservomin", setservomin);
//show some variables in the particle console
    Particle.variable("servomax", servomax);
    Particle.variable("servomin", servomin);
   // start off with a decent servo position, almost horizontal
	ServoPos("122");
	
	
	Serial.println("Setup done"); //useful for debugging
}

void loop() {
 
// just loop and wait for text to come in from the cloud

	//see if we need to perform a sweep of the servo
    fn_Sweep();
	
}


//send any text received to the serial port
//this is called by the particle cloud function
int sendText(String sToSend) {
    if( millis() >=20000){ // dont send empty string on startup
	Serial.println("You sent:");
	Serial.println(sToSend);
	Serial1.println(sToSend);
    }
    return 1;
}

int ServoPos(String sServoPos){
    int iServoPos = sServoPos.toInt();
      myservo.write(iServoPos); 
      pos = iServoPos;
      bSweep = false;
      return iServoPos;
}


//---------------------- everything below here manages servo sweep and fixed position ---------------------
int iSweepinterval = 30;

//set the delay between sweep increments - called from the cloud
int SetSweepInterval(String sinterval){
     iSweepinterval = sinterval.toInt();
      bSweep = true;
      return iSweepinterval;
}


//do the actual sweep - check every loop but only do stuff if actually sweeping
void fn_Sweep(){
    
    if (millis() - ilastsweep < iSweepinterval) return;
    ilastsweep = millis(); 
    if (!bSweep)return;
    
    
    //check limits
    if(pos < servomin){
        pos =servomin;
        bgoingup = true;
    }
    
    if(pos > servomax){
        pos =servomax;
        bgoingup = false;
    }
    
    //sweep in degrees of 1   
    if (bgoingup){
        pos +=1;
    } else {
        pos -=1;
    }
                                     // in steps of 1 degree
     myservo.write(pos);              // tell servo to go to position in variable 'pos'
         
	
}

//set servo sweep range - called from the cloud
int  setservomin (String sval){
    servomin = sval.toInt();
      bSweep = true;
    return servomin;
}



//set servo sweep range - called from the cloud
int  setservomax (String sval){
    servomax = sval.toInt();
      bSweep = true;
    return servomax;
}