Published November 22, 2016

Pan-Tilt Controller Using Particle Photon and Bluetooth

A pan-tilt controller locally controlled by a Photon and remotely via Bluetooth, physical potentiometers and another Photon.

IntermediateProtip2 hours1,754

Pan-Tilt Controller Using Particle Photon and Bluetooth

Things used in this project

Hardware components

Particle Photon

HC-05 Bluetooth Module

HiTech HS-5685MH Servo

Story

What is the Pan-Tilt Controller

The Pan-Tilt controller (the device on the left) is made up of 2 servos. These servos are controlled by a Particle Photon. Even though the Particle Photon is Wi-Fi enabled, I'm not using it in this demo yet. The Photon is hooked up to an HC-05 module configured as a Slave Bluetooth device.

The device on the right hand side is the remote controller. This device is made up of another Particle Photon. This Photon gets analog signals from the two potentiometers (the Pan and Tilt controls) and the Photon calculates the position the servos needs to be rotated at and transmits this data using another HC-05 Bluetooth device configured as a Bluetooth Master (this is the device that initiates the initial Bluetooth connection).

Pan-Tilt Controller Video on YouTube

Improvements I had to make

The initial project used the inclinometer on my phone and Bluetooth connection from the phone to the Pan-Tilt controller to control the Pan-Tilt. By simply tilting the phone up or down (pitch) the tilt servo would move. Or tilting the phone side to side (roll) the pan servo would move. As cool as this looked, it wasn't practical for my use since it implied you would have to hold the phone in a steady position once you've achieved the desired position.

So, I switched over to using a separate device (instead of a phone) as the remote controller, that used potentiometers instead. This works really well and feels surreal. Twisting a pair of knobs in one place and seeing something move somewhere else. And once you've achieved the desired position, it just stays there until you decide otherwise. I thought about using quadrature encoders but felt those would be better suited for controlling stepper motors instead where one could step the motor at 1/16 step for fine grained control. That project is planned!

The Pan-Tilt controller is powered by a 5V 5Amp power supply. That is, the servos, the Photon and the HC-05 are all powered by this power supply. The servos I'm using are high-torque servos (Hs-5685HM) and thus could draw a lot more current than any microcontroller can deliver.

Code

#define panReadPin A0
#define tiltReadPin A1

unsigned long panTiltReadInterval = 30;
unsigned long panTiltReadLastTime;

USARTSerial& buletoothSerial = Serial1;

void setup() {
    buletoothSerial.begin(9600);
}

void loop() {
    
    unsigned long elapsedMillis = millis();
    
     if (elapsedMillis - panTiltReadLastTime >= panTiltReadInterval)
     {
        panTiltReadLastTime = elapsedMillis;
    
        int panValueRead = analogRead(panReadPin);
        int tiltValueRead = analogRead(tiltReadPin);
  
        if (buletoothSerial.available())
        {  
              Serial.write(buletoothSerial.read());
        }

        unsigned int panValue = map(panValueRead, 0, 4095, 800, 2255);
        unsigned int tiltValue = map(tiltValueRead, 0, 4095, 755, 2240);

        buletoothSerial.print(panValue);
        buletoothSerial.write(',');
        buletoothSerial.print(tiltValue);
        buletoothSerial.write('|');
     }
}

#define bufferSize 1024
#define panServoPin D0
#define tiltServoPin D1
#define panServoMin 800
#define panServoMax 2255
#define tiltServoMin 755
#define tiltServoMax 2240


byte buffer[bufferSize];
const char delimiters[3] = ",|";
int bytesRead;

USARTSerial& buletoothSerial = Serial1;
Servo panServo;
Servo tiltServo;


void setup() {
    buletoothSerial.begin(9600);
    panServo.attach(panServoPin);
    tiltServo.attach(tiltServoPin);
    
    // Center the Servos
    panServo.writeMicroseconds(1528);
    tiltServo.writeMicroseconds(1498);
}

void loop() {
    
    while (buletoothSerial.available() > 0) {
        byte byt = buffer[bytesRead] = buletoothSerial.read();
        buffer[bytesRead] = byt;
        bytesRead++;
        
        if (byt == 124)
        {
            char* tempPayload = (char*)malloc(bytesRead + 1);
            memcpy(tempPayload, buffer, bytesRead);
            tempPayload[bytesRead] = NULL;
            bytesRead = 0;
            
            double panValue = strtod(strtok(tempPayload, delimiters), NULL);
            double tiltValue = strtod(strtok(NULL, delimiters), NULL);
            free(tempPayload);
            
            panValue = constrain(panValue, panServoMin, panServoMax);
            tiltValue = constrain(tiltValue, tiltServoMin, tiltServoMax);
            panServo.writeMicroseconds(panValue);
            tiltServo.writeMicroseconds(tiltValue);
        }
        
        Particle.process();
    }
}

Credits

Shiv Kumar

1 project • 3 followers

Studied Electronics Engineering. Developed and manufactured a bunch of Automotive electronic aftermarket kits. Now a Software Engineer

Pan-Tilt Controller Using Particle Photon and Bluetooth

Things used in this project

Hardware components

Story

What is the Pan-Tilt Controller

Improvements I had to make

Schematics

The Pan-Tilt Remote Controller

The Pan-Tilt Remote Controller - Front View

The Pan-Tilt Remote Controller - Closeup View

The Pan-Tilt Remote Controller - Showing wiring on the perma breadboard

Pan-Tilt Controller - Photon

Pan-Tilt Controller - Showing the Photon board and the Power supply board

Code

Pan-Tilt Remote controller