Touch Sensor - How to Use Touch Sensor

Tutorial Video

Hardware

• PHPoC Blue or PHPoC Black
• Micro USB to USB Cable (to upload source code to PHPoC Device)
• Touch Sensor
• Jumper wires

About Touch Sensor

Touch sensor is used to detect the touch of finger. The touch sensor used in this example includes three pins:

• VCC pin.
• GND pin.
• Signal pin (outputs digital signal).

How the touch sensor works:

• If sensor is touched by finger, value of the sensor's signal pin is HIGH (VCC).
• Otherwise, value of sensor's signal pin is LOW (0 V).

How to use touch sensor:

• By reading value of sensor's signal pin, we can infer state of touch sensor. To read value of sensor's signal pin, we just need to connect the sensor's signal pin to PHPoC device's input pin and use PHPoC code to read the value.

We can use another kind of touch sensor instead, even if it has different pinout, for example:

• Grove touch sensor (for more convenience, use it in combination with PHPoC Grove Expansion Board).

We can use the source code of this example if its working principle is the same as the touch sensor used in this example.




Wiring Diagram



Quick Steps

Source code of this example is a part of PHPoC Support Packet (PSP). You need to:

• Download PHPoC Support Package.
• Upload example\p4s\01.php_task\01.uio_touch_sensor to PHPoC Blue/Black.
• Click "Run" button on PHPoC Debugger.

If you use PHPoC for the first time, see How To Use PSP.


Source Code

Source files includes:

• init.php: this file is run when PHPoC system is powered or reset. It is used to specify which file is run is system loop.
• task0.php: this file is run in system loop of PHPoC devices.

init.php

This file is run when PHPoC system is powered or reset. It is used to specify that task0.php is run is system loop.

<?php

system("php task0.php");

?>

task0.php

[Full Code]

<?php

if(_SERVER("REQUEST_METHOD"))
 exit; // avoid php execution via http request

include_once "/lib/sd_340.php";

define("IN_PIN", 0);

echo "PHPoC example : P4S-34X / UIO / Catalex Touch Sensor\r\n";

uio_setup(0, IN_PIN, "in");

$last_touch = 0;

while(1)
{
 $touch = uio_in(0, IN_PIN);

 if($touch != $last_touch)
 {
  if($touch)
   echo "touch ON\r\n";
  else
   echo "touch OFF\r\n";

  $last_touch = $touch;
 }
}

?>

[Explanation]

Source code of this file does:

• Setup IO pin to input mode.

In infinite loop:

• Read value from IO pin to know state of touch sensor.
• Print touch state to PHPoC Debugger's console.

See Also

• Touch Sensor - Monitoring Touch Sensor from Webpage using Hypertext.
• Touch Sensor - Monitoring Touch Sensor from Webpage with Image.
• Touch Sensor - Monitoring Touch Sensor via WebSocket.

Other Resources

• PHPoC System Files
• How PHPoC System Works
• How To Use PHPoC Support Package