Chapter 9 Touch Sensor
=========================
ESP32-S3 offers up to 14 capacitive touch GPIO, and as you can see from the previous 
section, mechanical switches are prone to jitter that must be eliminated when used, 
which is not the case with ESP32-S3's builtin touch sensor. In addition, on the 
service life, the touch switch also has advantages that mechanical switch is completely 
incomparable.

Project 9.1 Read Touch Sensor
------------------------------------
This project reads the value of the touch sensor and prints it out.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- Jumper Wire x1
  
Connect
^^^^^^^^^^^

.. image:: img/connect/9.1.png

Sketch
^^^^^^^
**Sketch_09.1_TouchRead**

.. image:: img/software/9.1.png

Download the code to ESP32-S3 WROOM, open the serial monitor, and set the baud 
rate to 115200. Touch jumper with hand. As shown in the following figure

.. image:: img/phenomenon/9.1-1.png

.. image:: img/phenomenon/9.1.png

Project 9.2 Touch Lamp
---------------------------
In this project, we will use ESP32-S3's touch sensor to create a touch switch lamp.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- LED x1
- Resistor 220Ω x1
- Jumper Wire x3
  
Connect
^^^^^^^
.. image:: img/connect/9.2.png

Sketch
^^^^^^^
**Sketch_09.2_TouchLamp**

.. image:: img/phenomenon/9.2.png
    
Download the code to ESP32-S3 WROOM, open the serial monitor, and set the baud 
rate to 115200. Touch jumper with hand. As shown in the following figure,

.. image:: img/phenomenon/9.2-1.png


.. image:: img/software/9.2.png

With a touch pad, the state of the LED changes with each touch, and the detection 
state of the touch sensor is printed in the serial monitor.

Code
^^^^^^
The following is the program code:

.. code-block:: C

    #define PIN_LED     21         // Define the LED pin
    #define TOUCH_PIN   14          // Use a valid touch pin on ESP32-S3
    #define PRESS_VAL   50000      // This threshold may need adjustment
    #define RELEASE_VAL 65000      // This threshold may need adjustment

    bool isProcessed = false;      // Flag to track if touch event has been processed

    void setup() {
    Serial.begin(115200);        // Initialize serial communication
    pinMode(PIN_LED, OUTPUT);    // Set LED pin as output
    }

    void loop() {
    int touchValue = touchRead(TOUCH_PIN);  // Read touch sensor value
    //Serial.println(touchValue);  // Print touch value for debugging

    if (touchValue < PRESS_VAL) {  // Note: Lower value indicates touch
        if (!isProcessed) {          // If touch hasn't been processed yet
        isProcessed = true;        // Mark as processed
        Serial.println("Released!");
        reverseGPIO(PIN_LED);      // Toggle LED state
        }
    }
    if (touchValue > RELEASE_VAL) {  // Touch released
        if (isProcessed) {             // If a touch was previously processed
        isProcessed = false;         // Reset processed flag
        Serial.println("Touch detected!");
        }
    }
    
    delay(50);  // Short delay to prevent too frequent readings
    }

    void reverseGPIO(int pin) {
    digitalWrite(pin, !digitalRead(pin));  // Toggle the state of the given pin
    }