Implement Capacitive Touch Sensor (C-T Method) with Digispark

README.md

Capactive Touch Sensor with Digispark

$ pio init -b digispark-tiny

main.ino

#include <Arduino.h>

#define PIN_CP_HS 0
#define PIN_CP_LS 1

void blink(uint16_t ms) {
    analogWrite(4, 10);
    delay(ms);
    analogWrite(4, 0);
    delay(ms);
}

void setup() {
    pinMode(PIN_CP_HS, OUTPUT);
    pinMode(PIN_CP_LS, OUTPUT);
    pinMode(4, OUTPUT);

    blink(200);
}

void loop() {
    // reset
    pinMode(PIN_CP_LS, OUTPUT);
    pinMode(PIN_CP_HS, OUTPUT);
    digitalWrite(PIN_CP_LS, LOW);
    digitalWrite(PIN_CP_HS, LOW);
    delay(1);

    uint16_t counter = 0;
    while(true) {
        // charge
        pinMode(PIN_CP_LS, INPUT);
        digitalWrite(PIN_CP_LS, LOW);
        digitalWrite(PIN_CP_HS, HIGH);
        pinMode(PIN_CP_HS, OUTPUT);

        // transfer
        pinMode(PIN_CP_HS, INPUT);
        digitalWrite(PIN_CP_HS, LOW);
        pinMode(PIN_CP_LS, OUTPUT);
        digitalWrite(PIN_CP_LS, LOW);

        counter++;

        if(digitalRead(PIN_CP_HS)) {
            if(counter < 30) { // Adjust as you need
                blink(counter * 10);
            }
            break;
        }
    }
}

main2.ino

#include <Arduino.h>

#define PIN_CP_HS 0
#define PIN_CP_LS 2
#define PIN_ALERT 4
#define PIN_LED 1

void setup() {
    pinMode(PIN_CP_HS, OUTPUT);
    pinMode(PIN_CP_LS, OUTPUT);
    pinMode(PIN_ALERT, OUTPUT);
    pinMode(PIN_LED, OUTPUT);
    digitalWrite(PIN_LED, HIGH);
    delay(200);
    digitalWrite(PIN_LED, LOW);
}

int8_t detected = 0;
void loop() {
    // reset
    pinMode(PIN_CP_LS, OUTPUT);
    pinMode(PIN_CP_HS, OUTPUT);
    digitalWrite(PIN_CP_LS, LOW);
    digitalWrite(PIN_CP_HS, LOW);
    delayMicroseconds(10);

    uint16_t counter = 0;
    while(true) {
        // charge
        pinMode(PIN_CP_LS, INPUT);
        digitalWrite(PIN_CP_LS, LOW);
        digitalWrite(PIN_CP_HS, HIGH);
        pinMode(PIN_CP_HS, OUTPUT);

        // transfer
        pinMode(PIN_CP_HS, INPUT);
        digitalWrite(PIN_CP_HS, LOW);
        pinMode(PIN_CP_LS, OUTPUT);
        digitalWrite(PIN_CP_LS, LOW);

        counter++;

        if(digitalRead(PIN_CP_HS)) {
            if(counter < 500) {
                detected++;
            } else {
                detected--;
            }
            if(detected >= 5) {
                detected = 0;
                digitalWrite(PIN_ALERT, HIGH);
                digitalWrite(PIN_LED, HIGH);
            } else if(detected <= -5) {
                detected = 0;
                digitalWrite(PIN_ALERT, LOW);
                digitalWrite(PIN_LED, LOW);
            }
            break;
        }
    }
}