Last Updated or created 2022-11-02

Coline sometimes plays games with her sisters online using my streaming server. (Due to Covid)

Some games are difficult because you have to point to a location on the table. So i came up with a laser pointer solution.

The idea is: Send a url to the players with a streaming camera, you see the game on your screen but you can click on a location on the screen to move a laser pointer to that location.

Below is a proof of concept using the Lasercut worldmap on the wall and a website with a worldmap.

Code to place on the ESP:

This will connect to the MQTT broker and listens for messages on the servo/pan and tilt topic.

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <Servo.h> 
Servo pan; 
Servo tilt;

const char* ssid = "MYSSI";                
const char* password = "MYWIFIPASS";
const char* mqtt_server = "IPMQTTBROKER";
const char* topic_pan = "servo/pan";
const char* topic_tilt = "servo/tilt";
 
WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

void setup() {
  pan.attach(D5);
  tilt.attach(D6);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void setup_wifi() {
  delay(5);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
}

void callback(char* topic, byte* payload, unsigned int length) {
 String string;
 for (int i = 0; i < length; i++) {
 string+=((char)payload[i]); 
 }
 int pos = string.toInt(); 
 if ( strcmp(topic, topic_pan) == 0 ) {
 pan.write(pos); 
 }
 if ( strcmp(topic, topic_tilt) == 0 ) {
 tilt.write(pos); 
 }
 delay(15); 
}

void reconnect() {
  while (!client.connected()) {
    if (client.connect("ESP8266Client")) {
      client.subscribe(topic_pan); 
      client.subscribe(topic_tilt); 
    } else {
      delay(5000);
    }
  }
}
void loop() {   
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  delay(100);
}

Website PHP code:

This has some calibration code to get coordinates lined-up

<?Php
$foo_x=$_POST['foo_x'];
$foo_y=$_POST['foo_y'];
echo "X=$foo_x, Y=$foo_y ";
$x=160 - round($foo_x/30);
$y=38 - round($foo_y/100);

system('/usr/bin/mosquitto_pub -h 10.1.0.17 -t servo/pan -m "' . $x . '"');
system('/usr/bin/mosquitto_pub -h 10.1.0.17 -t servo/tilt -m "' . $y . '"');
?>
<form action='' method=post>
<input type="image" alt=' Finding coordinates of an image' src="worldmap.jpg"
name="foo" style=cursor:crosshair;/>
</form>

POC