How to Use Capacitive Touch Breakout: Examples, Pinouts, and Specs

The Capacitive Touch Breakout is an innovative electronic component that leverages the Atmel AT42QT1010 sensor to provide capacitive touch sensing capabilities. This breakout board is designed to detect touch or proximity by sensing changes in capacitance on a conductive pad. It is commonly used to create touch buttons or to replace traditional mechanical switches in a variety of applications, including consumer electronics, home automation, and interactive installations.

• Operating Voltage: 2.0V to 5.5V
• Current Consumption: 1.8µA (typical) when idle, 17µA (max) in active mode
• Interface: Digital output (active low)
• Response Time: 60ms (max) to touch or release
• Sensitivity: Adjustable with external capacitor (Cs)
• Dimensions: Typically in a small form factor (exact dimensions vary by manufacturer)

1. Power Supply: Connect VDD to a 2.0V to 5.5V power source and GND to the ground.
2. Sensor Pad: Attach a conductive pad to the SNS pin. The size of the pad can affect sensitivity.
3. Sensitivity Adjustment: Connect an external capacitor (Cs) between SNSK and SNS to set the sensitivity.
4. Output Signal: Connect the OUT pin to a digital input on your microcontroller to read the touch state.

• Use a stable power supply to minimize false triggering.
• Keep the sensor pad and traces away from noisy power lines or high-frequency signals.
• Calibrate the sensitivity using the external capacitor (Cs) to suit your application.
• Implement software debouncing to filter out spurious signals.

// Define the touch sensor output pin
const int touchPin = 2; // Connect the OUT pin of the breakout to digital pin 2

void setup() {
  pinMode(touchPin, INPUT_PULLUP); // Set the touch pin as an input with an internal pull-up resistor
  Serial.begin(9600); // Start serial communication at 9600 baud
}

void loop() {
  // Read the state of the touch sensor
  bool isTouched = digitalRead(touchPin) == LOW; // Active low means touched

  // Print the state to the serial monitor
  Serial.println(isTouched ? "Touched" : "Not touched");

  delay(100); // Small delay to debounce and prevent flooding the serial output
}

• No response to touch: Ensure the sensor pad is properly connected and the sensitivity is correctly set.
• False triggering: Check for noise in the power supply or nearby high-frequency signals. Adjust the external capacitor for better filtering.
• Intermittent operation: Verify that all connections are secure and there are no cold solder joints.

• Calibrating Sensitivity: Start with a 10pF capacitor and adjust as needed for your specific application.
• Debouncing: Implement a software debounce by requiring a consistent read over multiple cycles before changing state.
• Power Supply Noise: Use capacitors to filter the power supply if noise is suspected.

Remember, the Capacitive Touch Breakout is a versatile component that can enhance the user interface of your project. With proper setup and calibration, it can provide a reliable touch interface.