Arduino Xbee Wireless Full-Range Joystick FPS Servo Turret

Here we look at a full-range servo turret controlled wirelessly by Arduino via Xbee modules. The title says "fps" because if you were to have the point of view of the pencil tip, the joystick would control like an fps video game.

It works by moving the turret whenever the joystick is moved outside the neutral center position, and stays at whatever position its at when the joystick is moved back to the center position. Just like an fps video game.

You may have noticed, one joystick is superfluous in this demo. That will be used when (or if) I create an "fps bot", which would have a live wireless camera, omni wheels, and other things to allow for an fps control of a physical robot that has all of the movement freedom of a typical fps video game.

This project utilized Xbee modules with the FTDI-ready adapter that can be found at www.adafruit.com, Arduino Duemilanove, HS-311 Standard servos, and these adafruit.com joysticks.

Here's an Arduino Reference, if you need it. For the Xbees, plenty of resources online can help you configure and set it up. Good luck!

Below are two codes, one for the controller and one for the reciever. If you guys need help, comment on my corresponding Youtube video and I will try to get to it, as I am on Youtube quite often.

Controller code:

//CONTROLLER CODE
//Feel free to use this code however you like, but please credit lordvon and this site!
//'ud' and 'lr' are the pot signals for the up/down and left/right pots, respectively.

//(Joysticks and their pot values are not perfect, so some things have to be empirically
//determined. The serial read function is a great tool for collecting the values.)
//range of ud: 29-1014 (middle: around 479-540; avg:~510, center:+/-35)
//range of lr: 0-960 (middle: around 419-471; avg:445, center:+/-30)
//minimum range extreme (from avg) magnitude: 445
//maximum tolerance value: 35

//Print values as 'topic:value', where 'topic' denotes either 'ud' or 'lr',
//and 'value' is the associated pot value.
//Reciever is prompted to record by ':', and ended by ','.

//"" gives characters, '' gives characters in integer form.

//Empirically determined and/or arbitrary constants.
#define ud1 0
#define lr1 1
#define highpulse 2400
#define lowpulse 600
#define lr1avg 445
#define ud1avg 510
#define tolerance1 40
#define range1 445
#define maxadd 35

int ud1val;
int lr1val;
int lr1pulse;
int ud1pulse;
int lr1previous;
int ud1previous;
boolean update;

void setup()
{
Serial.begin(9600);
//initialize servo to its center position.
lr1previous = lr1avg;
ud1previous = ud1avg;
Serial.print(':');
Serial.print((highpulse-lowpulse)/2+lowpulse);
Serial.print(',');
Serial.print((highpulse-lowpulse)/2+lowpulse);
}

void loop()
{
ud1val = analogRead(ud1);
lr1val = analogRead(lr1);
update = (abs(lr1avg-lr1val) > tolerance1) || (abs(ud1avg-ud1val) > tolerance1);
if (update)
{
lr1val = newval(lr1val,(lr1avg-range1),(lr1avg+range1),lr1avg,lr1previous);
ud1val = newval(ud1val,(ud1avg-range1),(ud1avg+range1),ud1avg,ud1previous);
lr1previous = lr1val;
ud1previous = ud1val;
lr1pulse = map(lr1val,(lr1avg-range1),(lr1avg+range1),lowpulse,highpulse);
ud1pulse = map(ud1val,(ud1avg-range1),(ud1avg+range1),lowpulse,highpulse);
//':' is packet delimiter, ',' is UD/LR delimiter.
//Each cycle of delimiters denote a packet.
//Packet: UD value first, then LR value. (:UD,LR:)
Serial.print(':');
Serial.print(ud1pulse);
Serial.print(',');
Serial.print(lr1pulse);
delay(25);
update = false;
}
}

int newval(int val, int minval, int maxval, int avgval, int previousval)
{
int increment;
increment = val-avgval;
if (increment > 0)
{
increment = increment - tolerance1;
}
else if (increment < 0) { increment = increment + tolerance1; } increment = map(increment,0,range1-tolerance1,0,maxadd); val = increment + previousval; if (!(val <= maxval) || !(val >= minval))
{
if (val > maxval)
{
val = maxval;
}
else
{
val = minval;
}
}
return val;
}

Reciever code:

//RECIEVER CODE
//Feel free to use this code however you like, but please credit lordvon and this site!
#include <Servo.h>

Servo elevation;
Servo azimuth;

#define highpulse 2400
#define lowpulse 600

char received;
char pulsechar[4];
int counter=0;
int pulse;
boolean delimiter;

void setup()
{
Serial.begin(9600);
while (!Serial.available()){}
received = Serial.read();
elevation.attach(12);
azimuth.attach(13);
}

void loop()
{
// if (Serial.available())
// {
// Serial.println(char(Serial.read()));
// }
delimiter = (received == ',') || (received == ':');
if (!delimiter)
{
counter = 0;
while (!delimiter)
{
while (!Serial.available()){}
pulsechar[counter] = received;
counter += 1;
received = Serial.read();
delimiter = (received == ',') || (received == ':');
}
pulsechar[counter] = '\0';
pulse = atoi(pulsechar);
switch (received)
{
case ',':
azimuth.writeMicroseconds(pulse);
break;
case ':':
elevation.writeMicroseconds(pulse);
break;
}
}
else
{
while (!Serial.available()){}
received = Serial.read();
}
}