Initial Commit

CapacitiveButton.cpp

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+#include "CapacitiveButton.h"
+
+// This is a fast capacitive touch library that aims to have low response time for activation
+
+CapacitiveButton::CapacitiveButton(uint8_t sendPin, uint8_t receivePin, uint16_t nthreshold) : sensor(sendPin, receivePin) {
+  threshold = nthreshold;
+}
+
+bool CapacitiveButton::getState() {
+  return state;
+}
+
+uint16_t CapacitiveButton::getRaw() {
+  return average;
+}
+
+bool CapacitiveButton::update() {
+  uint16_t reading = sensor.capacitiveSensor(1);
+  uint16_t last_cycletime = millis() - last_time;
+  last_cycletime += last_cycletime ? 0 : 1; // prevent divide by zero
+  last_time = millis();
+  // average = (reading + average * SMOOTHING_CYCLES) / (SMOOTHING_CYCLES + 1);
+  float cycletime_factor = SMOOTHING_TIME / (float) last_cycletime;
+  average = (reading + average * cycletime_factor) / (cycletime_factor + 1);
+  if (state != (average > threshold)) { // if state of button has changed
+    if (!state) { // if new state is active
+      average += TIMEOUT_FACTOR * threshold;
+      state = true;
+    }
+    else {
+      state = false;
+    }
+    return true;
+  }
+  return false;
+}
+

CapacitiveButton.h

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+#include <CapacitiveSensor.h>
+
+//#define SMOOTHING_CYCLES 10 // increase to reduce activation errors
+#define SMOOTHING_TIME 16 // smoothing time in milliseconds
+#define TIMEOUT_FACTOR 100 // increase to 600 for reduced repeated touches
+
+class CapacitiveButton {
+  public:
+  	CapacitiveButton(uint8_t sendPin, uint8_t receivePin, uint16_t threshold = 40);
+    bool getState();
+    uint16_t getRaw();
+    bool update(); // returns true when state has changed
+  private:
+    CapacitiveSensor sensor;
+    uint16_t threshold = 40;
+    bool state = false;
+    uint16_t average = 0;
+    uint16_t last_time = 0;
+};
+

examples/CapacitiveButtonExample/CapacitiveButtonExample.ino

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+#include "CapacitiveButton.h"
+
+CapacitiveButton btn1 = CapacitiveButton(2, 5);
+CapacitiveButton btn2 = CapacitiveButton(2, 6);
+
+void setup() {
+  Serial.begin(9600);
+}
+
+void loop() {
+  if (btn1.update() || btn2.update()) {
+    Serial.print(btn1.getState());
+    Serial.print("\t");
+    Serial.println(btn2.getState());
+  }
+  delay(1); // if the looptime is less than one ms, fluctuations will be more sensetive
+}

library.properties

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+name=CapacitiveButton
+version=0.0.1
+author=Ambrose Chua
+maintainer=Ambrose Chua
+sentence=CapacitiveSensor wrapper for capacitive buttons.
+paragraph=CapacitiveButton is a small wrapper around CapacitiveSensor that filters the raw capacitive sensor data for use as a button. Requires CapacitiveSensor to be installed. 
+category=Sensors
+url=http://playground.arduino.cc/Main/CapacitiveSensor
+architectures=*