Hardware Connections

The TTP229 Capacitive Touch Sensor has to be connected to Uno as follows:

• Vcc to 5V
• Gnd to Gnd
• SCL to A5
• SDO to A4

Program for TTP229 Capacitive Touch Sensor

Before uploading the program,short the key as mentioned above and then upload the code given below.Now press the keys and corresponding number will be displayed in the serial monitor.

#define SCL_PIN A5
#define SDO_PIN A4
/* Used to store the key state */
byte Key;
void setup()
{
 /* Initialize the serial interface */
 Serial.begin(9600);
 /* Configure the clock and data pins */
 pinMode(SCL_PIN, OUTPUT);  
 pinMode(SDO_PIN, INPUT); 
}
/* Main program */
void loop()
{
 /* Read the current state of the keypad */
 Key = Read_Keypad();
 /* If a key has been pressed output it to the serial port */
 if (Key)
 Serial.println(Key); 
 /* Wait a little before reading again 
  so not to flood the serial port*/
 delay(100);
}
/* Read the state of the keypad */
byte Read_Keypad(void)
{
 byte Count;
 byte Key_State = 0;
 /* Pulse the clock pin 16 times (one for each key of the keypad) 
    and read the state of the data pin on each pulse */
 for(Count = 1; Count <= 16; Count++)
 {
   digitalWrite(SCL_PIN, LOW); 
  /* If the data pin is low (active low mode) then store the 
      current key number */
   if (!digitalRead(SDO_PIN))
     Key_State = Count; 
     digitalWrite(SCL_PIN, HIGH);
 }  
 return Key_State; 
}