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// Touch screen library with X Y and Z (pressure) readings as well
// as oversampling to avoid 'bouncing'
// (c) ladyada / adafruit
// Code under MIT License
#include "pins_arduino.h"
#include "wiring_private.h"
#include <avr/pgmspace.h>
#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
Point::Point(void) {
x = y = 0;
}
Point::Point(int16_t x0, int16_t y0, int16_t z0) {
x = x0;
y = y0;
z = z0;
}
bool Point::operator==(Point p1) {
return ((p1.x == x) && (p1.y == y) && (p1.z == z));
}
bool Point::operator!=(Point 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
Point TouchScreen::getPoint(void) {
int x, y, z;
int samples[NUMSAMPLES];
uint8_t i, valid;
uint8_t xp_port = digitalPinToPort(_xp);
uint8_t yp_port = digitalPinToPort(_yp);
uint8_t xm_port = digitalPinToPort(_xm);
uint8_t ym_port = digitalPinToPort(_ym);
uint8_t xp_pin = digitalPinToBitMask(_xp);
uint8_t yp_pin = digitalPinToBitMask(_yp);
uint8_t xm_pin = digitalPinToBitMask(_xm);
uint8_t ym_pin = digitalPinToBitMask(_ym);
valid = 1;
pinMode(_yp, INPUT);
pinMode(_ym, INPUT);
*portOutputRegister(yp_port) &= ~yp_pin;
*portOutputRegister(ym_port) &= ~ym_pin;
//digitalWrite(_yp, LOW);
//digitalWrite(_ym, LOW);
pinMode(_xp, OUTPUT);
pinMode(_xm, OUTPUT);
//digitalWrite(_xp, HIGH);
//digitalWrite(_xm, LOW);
*portOutputRegister(xp_port) |= xp_pin;
*portOutputRegister(xm_port) &= ~xm_pin;
for (i=0; i<NUMSAMPLES; i++) {
samples[i] = analogRead(_yp);
}
#if NUMSAMPLES > 2
insert_sort(samples, NUMSAMPLES);
#endif
#if NUMSAMPLES == 2
if (samples[0] != samples[1]) { valid = 0; }
#endif
x = (1023-samples[NUMSAMPLES/2]);
pinMode(_xp, INPUT);
pinMode(_xm, INPUT);
*portOutputRegister(xp_port) &= ~xp_pin;
//digitalWrite(_xp, LOW);
pinMode(_yp, OUTPUT);
*portOutputRegister(yp_port) |= yp_pin;
//digitalWrite(_yp, HIGH);
pinMode(_ym, OUTPUT);
for (i=0; i<NUMSAMPLES; i++) {
samples[i] = analogRead(_xm);
}
#if NUMSAMPLES > 2
insert_sort(samples, NUMSAMPLES);
#endif
#if NUMSAMPLES == 2
if (samples[0] != samples[1]) { valid = 0; }
#endif
y = (1023-samples[NUMSAMPLES/2]);
// Set X+ to ground
pinMode(_xp, OUTPUT);
*portOutputRegister(xp_port) &= ~xp_pin;
//digitalWrite(_xp, LOW);
// Set Y- to VCC
*portOutputRegister(ym_port) |= ym_pin;
//digitalWrite(_ym, HIGH);
// Hi-Z X- and Y+
*portOutputRegister(yp_port) &= ~yp_pin;
//digitalWrite(_yp, LOW);
pinMode(_yp, INPUT);
int z1 = analogRead(_xm);
int z2 = analogRead(_yp);
if (_rxplate != 0) {
// now read the x
float rtouch;
rtouch = z2;
rtouch /= z1;
rtouch -= 1;
rtouch *= x;
rtouch *= _rxplate;
rtouch /= 1024;
z = rtouch;
} else {
z = (1023-(z2-z1));
}
if (! valid) {
z = 0;
}
return Point(x, y, z);
}
TouchScreen::TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym) {
_yp = yp;
_xm = xm;
_ym = ym;
_xp = xp;
_rxplate = 0;
pressureThreshhold = 10;
}
TouchScreen::TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym,
uint16_t rxplate) {
_yp = yp;
_xm = xm;
_ym = ym;
_xp = xp;
_rxplate = rxplate;
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);
return (1023-analogRead(_yp));
}
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);
return (1023-analogRead(_xm));
}
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);
int z1 = analogRead(_xm);
int z2 = analogRead(_yp);
if (_rxplate != 0) {
// now read the x
float rtouch;
rtouch = z2;
rtouch /= z1;
rtouch -= 1;
rtouch *= readTouchX();
rtouch *= _rxplate;
rtouch /= 1024;
return rtouch;
} else {
return (1023-(z2-z1));
}
}
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