libraries/Adafruit_Circuit_Playground/utility/CPlay_CapacitiveSensor.cpp

/*
 CapacitiveSense.h v.04 - Capacitive Sensing Library for 'duino / Wiring
 https://github.com/PaulStoffregen/CapacitiveSensor
 http://www.pjrc.com/teensy/td_libs_CapacitiveSensor.html
 http://playground.arduino.cc/Main/CapacitiveSensor
 Copyright (c) 2009 Paul Bagder  All right reserved.
 Version 05 by Paul Stoffregen - Support non-AVR board: Teensy 3.x, Arduino Due
 Version 04 by Paul Stoffregen - Arduino 1.0 compatibility, issue 146 fix
 vim: set ts=4:
 */

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#include "pins_arduino.h"
#include "WConstants.h"
#endif

#include "CPlay_CapacitiveSensor.h"

/**************************************************************************/
/*! 
    @brief  Function that handles the creation and setup of instances
    @param sendPin send pin for the sensor
    @param receivePin the receiving pin for the sensor
*/
/**************************************************************************/
CPlay_CapacitiveSensor::CPlay_CapacitiveSensor(uint8_t sendPin, uint8_t receivePin)
{
	// initialize this instance's variables
	error = 1;
	loopTimingFactor = 300;		// determined empirically -  a hack

	CS_Timeout_Millis = (2000 * (float)loopTimingFactor * (float)F_CPU) / 16000000;
	CS_AutocaL_Millis = 20000;
	
	_sendPin = sendPin;
	_receivePin = receivePin;

	// Serial.print("timeOut =  ");
	// Serial.println(CS_Timeout_Millis);
	// get pin mapping and port for send Pin - from PinMode function in core

#ifdef NUM_DIGITAL_PINS
	if ((sendPin != 255) && (sendPin >= NUM_DIGITAL_PINS)) error = -3;
	if (receivePin >= NUM_DIGITAL_PINS) error = -2;
#endif
       	if (sendPin != -1) {      // sendpin to OUTPUT if we have one
#ifdef ARDUINO_TEEONARDU_FLORA	  // terrible hack!
	  DDRD |= _BV(5);
#else
	  pinMode(sendPin, OUTPUT);
#endif
	}

	pinMode(receivePin, INPUT);  // receivePin to INPUT

#ifdef ARDUINO_TEEONARDU_FLORA
	// terrible hack!
	PORTD &= ~_BV(5);
#else
	digitalWrite(sendPin, LOW);
#endif

       	if (sendPin != -1) {
	  send_outport =  portOutputRegister(digitalPinToPort(sendPin));
	  send_mask = digitalPinToBitMask(sendPin);
	} else {
	  send_outport = NULL;
	  send_mask = 0;
	}

	recv_outport =  portOutputRegister(digitalPinToPort(receivePin));
	recv_inport =  portInputRegister(digitalPinToPort(receivePin));
	recv_mask = digitalPinToBitMask(receivePin);
	recv_direction = portModeRegister(digitalPinToPort(receivePin));

	// get pin mapping and port for receive Pin - from digital pin functions in Wiring.c
	leastTotal = 0x0FFFFFFFL;   // input large value for autocalibrate begin
	lastCal = millis();         // set millis for start
}

// Public Methods //////////////////////////////////////////////////////////////
// Functions available in Wiring sketches, this library, and other libraries


/**************************************************************************/
/*! 
    @brief  get a capacitive sensor reading
    @param samples number of samples to take
    @return the sensor reading
*/
/**************************************************************************/
long CPlay_CapacitiveSensor::capacitiveSensor(uint8_t samples)
{
  total = 0;
  if (samples == 0) return 0;
  if (error < 0) {
    return -1;            // bad pin
  }

  pinMode(_receivePin, INPUT);

  for (uint8_t i = 0; i < samples; i++) {    // loop for samples parameter - simple lowpass filter
    if (SenseOneCycle() < 0)  return -2;   // variable over timeout
  }
	
  // only calibrate if time is greater than CS_AutocaL_Millis and total is less than 10% of baseline
  // this is an attempt to keep from calibrating when the sensor is seeing a "touched" signal
  
  if ( (millis() - lastCal > CS_AutocaL_Millis) && 
       abs(total  - leastTotal) < (int)(.10 * (float)leastTotal) ) {
    
    // Serial.println();               // debugging
    // Serial.println("auto-calibrate");
    // Serial.println();
    // delay(2000); */
    
    leastTotal = 0x0FFFFFFFL;          // reset for "autocalibrate"
    lastCal = millis();
  }
  /*else{                                // debugging
    Serial.print("  total =  ");
    Serial.print(total);
    
    Serial.print("   leastTotal  =  ");
    Serial.println(leastTotal);
    
    Serial.print("total - leastTotal =  ");
    x = total - leastTotal ;
    Serial.print(x);
    Serial.print("     .1 * leastTotal = ");
    x = (int)(.1 * (float)leastTotal);
    Serial.println(x);
    } */
  
  // routine to subtract baseline (non-sensed capacitance) from sensor return
  if (total < leastTotal) leastTotal = total;                 // set floor value to subtract from sensed value
  return(total - leastTotal);
}

/**************************************************************************/
/*! 
    @brief  get a raw sensor reading
    @param samples the number of samples to take
    @return -1 for error, -2 for timeout, other values are a raw sensor reading
*/
/**************************************************************************/
long CPlay_CapacitiveSensor::capacitiveSensorRaw(uint8_t samples)
{
  total = 0;
  if (samples == 0) return 0;
  if (error < 0) return -1;                  // bad pin - this appears not to work
  
  for (uint8_t i = 0; i < samples; i++) {    // loop for samples parameter - simple lowpass filter
    if (SenseOneCycle() < 0)  return -2;   // variable over timeout
  }
  
  return total;
}

/**************************************************************************/
/*! 
    @brief  reset the auto calibration
*/
/**************************************************************************/
void CPlay_CapacitiveSensor::reset_CS_AutoCal(void){
  leastTotal = 0x0FFFFFFFL;
}

/**************************************************************************/
/*! 
    @brief set the auto-calibration time
    @param autoCal_millis the desired calibration time in milliseconds
*/
/**************************************************************************/
void CPlay_CapacitiveSensor::set_CS_AutocaL_Millis(unsigned long autoCal_millis){
  CS_AutocaL_Millis = autoCal_millis;
}

/**************************************************************************/
/*! 
    @brief  set the sensor timeout
    @param timeout_millis the number of milliseconds to set the timeout to
*/
/**************************************************************************/
void CPlay_CapacitiveSensor::set_CS_Timeout_Millis(unsigned long timeout_millis){
  CS_Timeout_Millis = (timeout_millis * (float)loopTimingFactor * (float)F_CPU) / 16000000;  // floats to deal with large numbers
}

// Private Methods /////////////////////////////////////////////////////////////
// Functions only available to other functions in this library

/**************************************************************************/
/*! 
    @brief  sense a single sicle
    @return the reading
*/
/**************************************************************************/
int CPlay_CapacitiveSensor::SenseOneCycle(void)
{
  if (send_mask != 0) {
    noInterrupts();
    *send_outport &= ~send_mask;           // sendPin Register low
    *recv_direction &= ~recv_mask;	// receivePin to input (pullups are off)
    *recv_direction |= recv_mask;       // receivePin to OUTPUT
    *recv_outport &= ~recv_mask;    	// pin is now LOW AND OUTPUT
    delayMicroseconds(10);
    *recv_direction &= ~recv_mask;	// receivePin to input (pullups are off)
    *send_outport |= send_mask;           // sendPin Register high
    interrupts();
    
    while ( !(*recv_inport & recv_mask) && (total < CS_Timeout_Millis) ) {  // while receive pin is LOW AND total is positive value
      total++;
    }
    //Serial.print("SenseOneCycle(1): "); Serial.println(total);
    
    if (total > CS_Timeout_Millis) {
      return -2;         //  total variable over timeout
    }
  }

  // set receive pin HIGH briefly to charge up fully - because the while loop above will exit when pin is ~ 2.5V
  noInterrupts();
  *send_outport &= ~send_mask;           // sendPin Register low
  *recv_direction |= recv_mask;       // receivePin to OUTPUT
  *recv_outport |= recv_mask;    	// pin is now HIGH AND OUTPUT
  delayMicroseconds(10);
  *recv_direction &= ~recv_mask;	// receivePin to input (pullups are off)
  *recv_outport &= ~recv_mask;
  if (send_mask != 0) {
    *send_outport &= ~send_mask;           // sendPin Register high
  }
  interrupts();
  
  while ((*recv_inport & recv_mask) && (total < CS_Timeout_Millis) ) {
    total++; // while receive pin is HIGH  AND total is less than timeout
  }
  //Serial.print("SenseOneCycle(2): "); Serial.println(total);

  if (total >= CS_Timeout_Millis) {
    return -2;     // total variable over timeout
  } else {
    return 1;
  }
}