main.cpp

/*
 * main.cpp
 *
 *
 * 500K resistor and 5pF cap between D1 and ground
 * measured time 10-15uS without touch, >150uS with touch
 *
 */



#include "Arduino.h"

#define D1 5
#define CHARGE_TIME 500000 // 500ms
#define ERR_TIMEOUT -2
#define ERR_NOTREADY -1

long waitFor(int value) {
	unsigned long start = micros();
	unsigned long end = start + CHARGE_TIME; // 100ms is far too long
	unsigned long now = start;
	while(true) {
		if(now>end) { return ERR_TIMEOUT; }
		if(digitalRead(D1)==value) { break; }
		yield();
		now = micros();
	}
	return now - start;
}

long waitHigh() {
	return waitFor(HIGH);
}

long waitLow() {
	return waitFor(LOW);
}

void charge() {
	pinMode(D1, OUTPUT);
	digitalWrite(D1, HIGH);
//	Serial.print("charging...");
	delayMicroseconds(CHARGE_TIME); // wait for cap to charge
//	Serial.println("done");
}

void setup() {
	Serial.begin(9600);
	Serial.println("running test_captouch");
//	WiFi.forceSleepBegin();
	charge();
	Serial.println("setup complete");
}

long measure() {
	pinMode(D1, INPUT);
	long out = waitLow();
	charge();
	return out;
}

void loop() {
	long time = measure();
        // print sort of a bar graph -- #chars width = time/10
        // watch width change as you touch and release
	int i;
	for(i=0;i<time/10;i++) {
		Serial.print("-");
	}
	Serial.println("X");
}