openHASP/lib/TouchScreen/TouchScreen.cpp

// Touch screen library with X Y and Z (pressure) readings as well
// as oversampling to avoid 'bouncing'
// (c) ladyada / adafruit
// Code under MIT License
// Code under MIT License

#include "Arduino.h"
#include "pins_arduino.h"

#ifdef __AVR
#include <avr/pgmspace.h>
#elif defined(ESP8266)
#include <pgmspace.h>
#endif
#include "TouchScreen.h"

// increase or decrease the touchscreen oversampling. This is a little different than you make think:
// 1 is no oversampling, whatever data we get is immediately returned
// 2 is double-sampling and we only return valid data if both points are the same
// 3+ uses insert sort to get the median value.
// We found 2 is precise yet not too slow so we suggest sticking with it!

#define NUMSAMPLES 2

TSPoint::TSPoint(void)
{
    x = y = 0;
}

TSPoint::TSPoint(int16_t x0, int16_t y0, int16_t z0)
{
    x = x0;
    y = y0;
    z = z0;
}

bool TSPoint::operator==(TSPoint p1)
{
    return ((p1.x == x) && (p1.y == y) && (p1.z == z));
}

bool TSPoint::operator!=(TSPoint p1)
{
    return ((p1.x != x) || (p1.y != y) || (p1.z != z));
}

#if(NUMSAMPLES > 2)
static void insert_sort(int array[], uint8_t size)
{
    uint8_t j;
    int save;

    for(int i = 1; i < size; i++) {
        save = array[i];
        for(j = i; j >= 1 && save < array[j - 1]; j--) array[j] = array[j - 1];
        array[j] = save;
    }
}
#endif

TSPoint TouchScreen::getPoint(void)
{
    int x, y, z;
    int samples[NUMSAMPLES];
    uint8_t i, valid;

    valid = 1;

    pinMode(_yp, INPUT);
    pinMode(_ym, INPUT);
    pinMode(_xp, OUTPUT);
    pinMode(_xm, OUTPUT);

#if defined(USE_FAST_PINIO)
    *xp_port |= xp_pin;
    *xm_port &= ~xm_pin;
#else
    digitalWrite(_xp, HIGH);
    digitalWrite(_xm, LOW);
#endif

#ifdef __arm__
    delayMicroseconds(20); // Fast ARM chips need to allow voltages to settle
#endif

    for(i = 0; i < NUMSAMPLES; i++) {
#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
        samples[i] = analogRead(aYP);
#else
        samples[i] = analogRead(_yp);
#endif
    }

#if NUMSAMPLES > 2
    insert_sort(samples, NUMSAMPLES);
#endif
#if NUMSAMPLES == 2
    // Allow small amount of measurement noise, because capacitive
    // coupling to a TFT display's signals can induce some noise.
    if(samples[0] - samples[1] < -NOISE_LEVEL || samples[0] - samples[1] > NOISE_LEVEL) {
        valid = 0;
    } else {
        samples[1] = (samples[0] + samples[1]) >> 1; // average 2 samples
    }
#endif

    x = (ADC_MAX - samples[NUMSAMPLES / 2]);

    pinMode(_xp, INPUT);
    pinMode(_xm, INPUT);
    pinMode(_yp, OUTPUT);
    pinMode(_ym, OUTPUT);

#if defined(USE_FAST_PINIO)
    *ym_port &= ~ym_pin;
    *yp_port |= yp_pin;
#else
    digitalWrite(_ym, LOW);
    digitalWrite(_yp, HIGH);
#endif

#ifdef __arm__
    delayMicroseconds(20); // Fast ARM chips need to allow voltages to settle
#endif

    for(i = 0; i < NUMSAMPLES; i++) {
#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
        samples[i] = analogRead(aXM);
#else
        samples[i] = analogRead(_xm);
#endif
    }

#if NUMSAMPLES > 2
    insert_sort(samples, NUMSAMPLES);
#endif
#if NUMSAMPLES == 2
    // Allow small amount of measurement noise, because capacitive
    // coupling to a TFT display's signals can induce some noise.
    if(samples[0] - samples[1] < -NOISE_LEVEL || samples[0] - samples[1] > NOISE_LEVEL) {
        valid = 0;
    } else {
        samples[1] = (samples[0] + samples[1]) >> 1; // average 2 samples
    }
#endif

    y = (ADC_MAX - samples[NUMSAMPLES / 2]);

    // Set X+ to ground
    // Set Y- to VCC
    // Hi-Z X- and Y+
    pinMode(_xp, OUTPUT);
    pinMode(_yp, INPUT);

#if defined(USE_FAST_PINIO)
    *xp_port &= ~xp_pin;
    *ym_port |= ym_pin;
#else
    digitalWrite(_xp, LOW);
    digitalWrite(_ym, HIGH);
#endif

#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
    int z1 = analogRead(aXM);
    int z2 = analogRead(aYP);
#else
    int z1 = analogRead(_xm);
    int z2 = analogRead(_yp);
#endif

    if(_rxplate != 0) {
        // now read the x
        float rtouch;
        rtouch = z2;
        rtouch /= z1;
        rtouch -= 1;
        rtouch *= x;
        rtouch *= _rxplate;
        rtouch /= ADC_MAX + 1;

        z = rtouch;
    } else {
        z = (ADC_MAX - (z2 - z1));
    }

    if(!valid) {
        z = 0;
    }

    return TSPoint(x, y, z);
}

TouchScreen::TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym, uint16_t rxplate = 0)
{
    _yp      = yp;
    _xm      = xm;
    _ym      = ym;
    _xp      = xp;
    _rxplate = rxplate;

#if defined(USE_FAST_PINIO)
    xp_port = portOutputRegister(digitalPinToPort(_xp));
    yp_port = portOutputRegister(digitalPinToPort(_yp));
    xm_port = portOutputRegister(digitalPinToPort(_xm));
    ym_port = portOutputRegister(digitalPinToPort(_ym));

    xp_pin = digitalPinToBitMask(_xp);
    yp_pin = digitalPinToBitMask(_yp);
    xm_pin = digitalPinToBitMask(_xm);
    ym_pin = digitalPinToBitMask(_ym);
#endif

    pressureThreshhold = 10;
}

int TouchScreen::readTouchX(void)
{
    pinMode(_yp, INPUT);
    pinMode(_ym, INPUT);
    digitalWrite(_yp, LOW);
    digitalWrite(_ym, LOW);

    pinMode(_xp, OUTPUT);
    digitalWrite(_xp, HIGH);
    pinMode(_xm, OUTPUT);
    digitalWrite(_xm, LOW);

#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
    return (ADC_MAX - analogRead(aYP));
#else
    return (ADC_MAX - analogRead(_yp));
#endif
}

int TouchScreen::readTouchY(void)
{
    pinMode(_xp, INPUT);
    pinMode(_xm, INPUT);
    digitalWrite(_xp, LOW);
    digitalWrite(_xm, LOW);

    pinMode(_yp, OUTPUT);
    digitalWrite(_yp, HIGH);
    pinMode(_ym, OUTPUT);
    digitalWrite(_ym, LOW);

#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
    return (ADC_MAX - analogRead(aXM));
#else
    return (ADC_MAX - analogRead(_xm));
#endif
}

uint16_t TouchScreen::pressure(void)
{
    // Set X+ to ground
    pinMode(_xp, OUTPUT);
    digitalWrite(_xp, LOW);

    // Set Y- to VCC
    pinMode(_ym, OUTPUT);
    digitalWrite(_ym, HIGH);

    // Hi-Z X- and Y+
    digitalWrite(_xm, LOW);
    pinMode(_xm, INPUT);
    digitalWrite(_yp, LOW);
    pinMode(_yp, INPUT);

#if defined(ESP32_WIFI_TOUCH) && defined(ESP32)
    int z1 = analogRead(aXM);
    int z2 = analogRead(aYP);
#else
    int z1 = analogRead(_xm);
    int z2 = analogRead(_yp);
#endif

    if(_rxplate != 0) {
        // now read the x
        float rtouch;
        rtouch = z2;
        rtouch /= z1;
        rtouch -= 1;
        rtouch *= readTouchX();
        rtouch *= _rxplate;
        rtouch /= ADC_MAX + 1;

        return rtouch;
    } else {
        return (ADC_MAX - (z2 - z1));
    }
}