NodeMCU Interfaced Capacitive Touch (TTP224)

In this tutorial to interface the Capacitive Touch buttons module with ESP8266 12E Node MCU and an example we Connect a LCD display. The TTP224 module it has 4 pins for the different outputs, they are digital, and for the power it can be powered by 3.3V or 5V from the Arduino. The module has 4 built-in LEDs, they light up whenever the respective button is touched

The TTP224 touch controller is the exact non-contact alternative to traditional button switches.

Components Required

TTP224 Capacitive Touch Module

ESP8266 12E

LCD 16X2 with I2c Module

TTP224

TTP224 is a four-channel touch detector IC that could be used as a 4-touch key driver. It is a useful interface when replaced with a traditional button key. It has a low power consumption with a wide range of operating voltage.

TTP224 has an auto-calibration feature for life and it has a re-calibration period of about 4.0 seconds. The sensitivity can be adjusted using an external capacitor of 0 to 50 pF, 4 input features fewer component counts during the integration in the system.

Features and Specification of TTP224

• Four-channel touch key sensing

• 2.5V - 5.5V Operating Voltage

• Operating current 2.5uA typically in low power mode. Maximum operating current 9.0uA at Fast mode.

• Response time - 100ms at fast mode and 200ms at low power mode.

• Adjustable sensitivity using an external capacitor (0-50 pF)

• Stable touch detection of the human body

• All output modes can be configurable for high or active low by pad options.

• Direct mode and Toggle mode selection pin available

• Auro calibration feature for life. The re-calibration period is about 4.0sec when the key has not been touch.

• Provides one output pin TPQ0D that has no diode protection circuit inbuilt and it is active low

• Provides fast mode and low power mode selection by pad optional (LPMB pin).

• Provides direct mode or toggle mode, CMOS output, or open-drain output. active high or active low by option (TOG/AHLF/OD pin).

Circuit Connection

TTP224 out1 to out4 Pins are interfaced with D5 through D8 of NodeMCU

TTP224 VCC Pin are interfaced with Vin of NodeMCU.

TTP224 GND Pin are interfaced with GND of NodeMCU

LCD VCC Pin are interfaced with Vin of NodeMCU.

LCD GND Pin are interfaced with GND of NodeMCU

LCD SCL Pin are interfaced with D1 of NodeMCU.

LCD SDA Pin are interfaced with D2 of NodeMCU.

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arduino code

//WWW.DOFBOT.COM

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,16,2);

void setup() {

Serial.begin(9600);

// input pins

pinMode(14, INPUT); // TTP224 out1

pinMode(12, INPUT); // TTP224 out2

pinMode(13, INPUT); // TTP224 out3

pinMode(15, INPUT); // TTP224 out4

lcd.init(); // initialize the lcd

// Print a message to the LCD.

lcd.backlight();

lcd.setCursor(0,0);

lcd.print(" TTP224 Module ");

}

void loop() {

if(digitalRead(14)){

Serial.println("LED D1 ON"); // Turn the LED ON

lcd.setCursor(0,1);

lcd.print(" KEY1 Touched ");

}else{

Serial.println("LED D1 OFF");

}

// button 2 action

if(digitalRead(12)){

Serial.println("LED D2 ON"); // Turn the LED ON

lcd.setCursor(0,1);

lcd.print(" KEY2 Touched ");

}else{

Serial.println("LED D2 OFF");

}

if(digitalRead(13)){

Serial.println("LED D3 ON"); // Turn the LED ON

lcd.setCursor(0,1);

lcd.print(" KEY3 Touched ");

}else{

Serial.println("LED D3 OFF");

}

if(digitalRead(15)){

Serial.println("LED D4 ON"); // Turn the LED ON

lcd.setCursor(0,1);

lcd.print(" KEY4 Touched ");

}else{

Serial.println("LED D4 OFF");

}

}