added capacitivePin-feature

sketches/prototype/prototype.ino

@@ -28,6 +28,71 @@ void Version(){
   Serial.println("version");
 }
 
+uint8_t readCapacitivePin(String data) {
+  int pinToMeasure = Str2int(data);
+  // readCapacitivePin
+  //  Input: Arduino pin number
+  //  Output: A number, from 0 to 17 expressing
+  //  how much capacitance is on the pin
+  //  When you touch the pin, or whatever you have
+  //  attached to it, the number will get higher
+  //  http://playground.arduino.cc/Code/CapacitiveSensor
+  //
+  // Variables used to translate from Arduino to AVR pin naming
+  volatile uint8_t* port;
+  volatile uint8_t* ddr;
+  volatile uint8_t* pin;
+  // Here we translate the input pin number from
+  //  Arduino pin number to the AVR PORT, PIN, DDR,
+  //  and which bit of those registers we care about.
+  byte bitmask;
+  port = portOutputRegister(digitalPinToPort(pinToMeasure));
+  ddr = portModeRegister(digitalPinToPort(pinToMeasure));
+  bitmask = digitalPinToBitMask(pinToMeasure);
+  pin = portInputRegister(digitalPinToPort(pinToMeasure));
+  // Discharge the pin first by setting it low and output
+  *port &= ~(bitmask);
+  *ddr  |= bitmask;
+  delay(1);
+  // Make the pin an input with the internal pull-up on
+  *ddr &= ~(bitmask);
+  *port |= bitmask;
+
+  // Now see how long the pin to get pulled up. This manual unrolling of the loop
+  // decreases the number of hardware cycles between each read of the pin,
+  // thus increasing sensitivity.
+  uint8_t cycles = 17;
+       if (*pin & bitmask) { cycles =  0;}
+  else if (*pin & bitmask) { cycles =  1;}
+  else if (*pin & bitmask) { cycles =  2;}
+  else if (*pin & bitmask) { cycles =  3;}
+  else if (*pin & bitmask) { cycles =  4;}
+  else if (*pin & bitmask) { cycles =  5;}
+  else if (*pin & bitmask) { cycles =  6;}
+  else if (*pin & bitmask) { cycles =  7;}
+  else if (*pin & bitmask) { cycles =  8;}
+  else if (*pin & bitmask) { cycles =  9;}
+  else if (*pin & bitmask) { cycles = 10;}
+  else if (*pin & bitmask) { cycles = 11;}
+  else if (*pin & bitmask) { cycles = 12;}
+  else if (*pin & bitmask) { cycles = 13;}
+  else if (*pin & bitmask) { cycles = 14;}
+  else if (*pin & bitmask) { cycles = 15;}
+  else if (*pin & bitmask) { cycles = 16;}
+
+  // Discharge the pin again by setting it low and output
+  //  It's important to leave the pins low if you want to 
+  //  be able to touch more than 1 sensor at a time - if
+  //  the sensor is left pulled high, when you touch
+  //  two sensors, your body will transfer the charge between
+  //  sensors.
+  *port &= ~(bitmask);
+  *ddr  |= bitmask;
+
+  //return cycles;
+  Serial.println(cycles);
+}
+
 void Tone(String data){
   int idx = data.indexOf('%');
   int len = Str2int(data.substring(0,idx));
@@ -274,9 +339,11 @@ void SerialParser(void) {
   else if (cmd == "nto") {
       ToneNo(data);   
   }  
+  else if (cmd == "cap") {
+      readCapacitivePin(data);   
+  }  
 }
 
-
 void setup()  {
   Serial.begin(9600); 
     while (!Serial) {