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Added Adafruit Touchscreen Library
Added support for STM32 to the Adafruit Resistive Touchscreen library.
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‎STM32F1/libraries/Touch-Screen-Library_STM/README.txt‎

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This is the 4-wire resistive touch screen firmware for Arduino. Works with all Arduinos and the Mega
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To install, click DOWNLOAD SOURCE in the top right corner, and rename the uncompressed folder "TouchScreen". See our tutorial at http://www.ladyada.net/library/arduino/libraries.html on Arduino Library installation
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Ported to the STM32 by Jaret Burkett https://github.com/jaretburkett

‎STM32F1/libraries/Touch-Screen-Library_STM/TouchScreen_STM.cpp‎

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// Touch screen library with X Y and Z (pressure) readings as well
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// as oversampling to avoid 'bouncing'
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// (c) ladyada / adafruit
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// Code under MIT License
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// Ported to STM32 by Jaret Burkett https://github.com/jaretburkett
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#include "pins_arduino.h"
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#include "wiring_private.h"
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#ifdef __AVR
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#include <avr/pgmspace.h>
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#elif defined(ESP8266)
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#include <pgmspace.h>
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#elif defined (__STM32F1__)
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#include <avr/pgmspace.h>
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#include <WProgram.h>
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#endif
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#include "TouchScreen_STM.h"
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// increase or decrease the touchscreen oversampling. This is a little different than you make think:
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// 1 is no oversampling, whatever data we get is immediately returned
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// 2 is double-sampling and we only return valid data if both points are the same
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// 3+ uses insert sort to get the median value.
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// We found 2 is precise yet not too slow so we suggest sticking with it!
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#define NUMSAMPLES 2
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TSPoint::TSPoint(void) {
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x = y = 0;
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}
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TSPoint::TSPoint(int16_t x0, int16_t y0, int16_t z0) {
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x = x0;
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y = y0;
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z = z0;
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}
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bool TSPoint::operator==(TSPoint p1) {
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return ((p1.x == x) && (p1.y == y) && (p1.z == z));
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}
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bool TSPoint::operator!=(TSPoint p1) {
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return ((p1.x != x) || (p1.y != y) || (p1.z != z));
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}
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#if (NUMSAMPLES > 2)
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static void insert_sort(int array[], uint8_t size) {
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uint8_t j;
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int save;
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for (int i = 1; i < size; i++) {
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save = array[i];
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for (j = i; j >= 1 && save < array[j - 1]; j--)
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array[j] = array[j - 1];
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array[j] = save;
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}
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}
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#endif
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TSPoint TouchScreen::getPoint(void) {
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int x, y, z;
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int samples[NUMSAMPLES];
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uint8_t i, valid;
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#if !defined (__STM32F1__)
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uint8_t xp_port = digitalPinToPort(_xp);
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uint8_t yp_port = digitalPinToPort(_yp);
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uint8_t xm_port = digitalPinToPort(_xm);
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uint8_t ym_port = digitalPinToPort(_ym);
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uint8_t xp_pin = digitalPinToBitMask(_xp);
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uint8_t yp_pin = digitalPinToBitMask(_yp);
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uint8_t xm_pin = digitalPinToBitMask(_xm);
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uint8_t ym_pin = digitalPinToBitMask(_ym);
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#endif
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valid = 1;
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pinMode(_yp, INPUT);
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pinMode(_ym, INPUT);
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#if !defined (__STM32F1__)
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*portOutputRegister(yp_port) &= ~yp_pin;
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*portOutputRegister(ym_port) &= ~ym_pin;
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pinMode(_xp, OUTPUT);
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pinMode(_xm, OUTPUT);
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*portOutputRegister(xp_port) |= xp_pin;
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*portOutputRegister(xm_port) &= ~xm_pin;
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#else
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digitalWrite(_yp, LOW);
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digitalWrite(_ym, LOW);
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pinMode(_xp, OUTPUT);
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pinMode(_xm, OUTPUT);
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digitalWrite(_xp, HIGH);
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digitalWrite(_xm, LOW);
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#endif
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for (i=0; i<NUMSAMPLES; i++) {
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samples[i] = analogRead(_yp);
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}
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#if NUMSAMPLES > 2
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insert_sort(samples, NUMSAMPLES);
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#endif
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#if NUMSAMPLES == 2
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if (samples[0] != samples[1]) { valid = 0; }
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#endif
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#if !defined (__STM32F1__)
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x = (1023-samples[NUMSAMPLES/2]);
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#else
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x = (4095-samples[NUMSAMPLES/2]);
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#endif
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pinMode(_xp, INPUT);
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pinMode(_xm, INPUT);
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#if !defined (__STM32F1__)
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*portOutputRegister(xp_port) &= ~xp_pin;
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#else
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digitalWrite(_xp, LOW);
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#endif
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pinMode(_yp, OUTPUT);
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#if !defined (__STM32F1__)
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*portOutputRegister(yp_port) |= yp_pin;
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#else
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digitalWrite(_yp, HIGH);
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#endif
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pinMode(_ym, OUTPUT);
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for (i=0; i<NUMSAMPLES; i++) {
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samples[i] = analogRead(_xm);
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}
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#if NUMSAMPLES > 2
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insert_sort(samples, NUMSAMPLES);
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#endif
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#if NUMSAMPLES == 2
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if (samples[0] != samples[1]) { valid = 0; }
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#endif
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#if !defined (__STM32F1__)
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y = (1023-samples[NUMSAMPLES/2]);
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#else
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y = (4095-samples[NUMSAMPLES/2]);
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#endif
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pinMode(_xp, OUTPUT);
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#if !defined (__STM32F1__)
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// Set X+ to ground
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*portOutputRegister(xp_port) &= ~xp_pin;
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// Set Y- to VCC
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*portOutputRegister(ym_port) |= ym_pin;
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// Hi-Z X- and Y+
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*portOutputRegister(yp_port) &= ~yp_pin;
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#else
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// Set X+ to ground
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digitalWrite(_xp, LOW);
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// Set Y- to VCC
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digitalWrite(_ym, HIGH);
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// Hi-Z X- and Y+
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digitalWrite(_yp, LOW);
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#endif
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//digitalWrite(_yp, LOW);
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pinMode(_yp, INPUT);
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int z1 = analogRead(_xm);
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int z2 = analogRead(_yp);
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if (_rxplate != 0) {
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// now read the x
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float rtouch;
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rtouch = z2;
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rtouch /= z1;
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rtouch -= 1;
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rtouch *= x;
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rtouch *= _rxplate;
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#if !defined (__STM32F1__)
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rtouch /= 1024;
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#else
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rtouch /= 4095;
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#endif
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z = rtouch;
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} else {
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#if !defined (__STM32F1__)
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z = (1023-(z2-z1));
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#else
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z = (4095-(z2-z1));
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#endif
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}
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if (! valid) {
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z = 0;
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}
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return TSPoint(x, y, z);
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}
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TouchScreen::TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym) {
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_yp = yp;
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_xm = xm;
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_ym = ym;
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_xp = xp;
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_rxplate = 0;
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pressureThreshhold = 10;
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}
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TouchScreen::TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym,
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uint16_t rxplate) {
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_yp = yp;
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_xm = xm;
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_ym = ym;
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_xp = xp;
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_rxplate = rxplate;
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pressureThreshhold = 10;
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}
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int TouchScreen::readTouchX(void) {
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pinMode(_yp, INPUT);
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pinMode(_ym, INPUT);
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digitalWrite(_yp, LOW);
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digitalWrite(_ym, LOW);
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pinMode(_xp, OUTPUT);
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digitalWrite(_xp, HIGH);
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pinMode(_xm, OUTPUT);
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digitalWrite(_xm, LOW);
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#if !defined (__STM32F1__)
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return (1023-analogRead(_yp));
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#else
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return (4095-analogRead(_yp));
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#endif
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}
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int TouchScreen::readTouchY(void) {
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pinMode(_xp, INPUT);
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pinMode(_xm, INPUT);
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digitalWrite(_xp, LOW);
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digitalWrite(_xm, LOW);
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pinMode(_yp, OUTPUT);
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digitalWrite(_yp, HIGH);
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pinMode(_ym, OUTPUT);
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digitalWrite(_ym, LOW);
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#if !defined (__STM32F1__)
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return (1023-analogRead(_xm));
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#else
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return (4095-analogRead(_xm));
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#endif
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}
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uint16_t TouchScreen::pressure(void) {
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// Set X+ to ground
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pinMode(_xp, OUTPUT);
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digitalWrite(_xp, LOW);
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// Set Y- to VCC
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pinMode(_ym, OUTPUT);
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digitalWrite(_ym, HIGH);
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// Hi-Z X- and Y+
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digitalWrite(_xm, LOW);
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pinMode(_xm, INPUT);
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digitalWrite(_yp, LOW);
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pinMode(_yp, INPUT);
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int z1 = analogRead(_xm);
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int z2 = analogRead(_yp);
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if (_rxplate != 0) {
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// now read the x
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float rtouch;
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rtouch = z2;
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rtouch /= z1;
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rtouch -= 1;
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rtouch *= readTouchX();
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rtouch *= _rxplate;
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#if !defined (__STM32F1__)
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rtouch /= 1024;
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#else
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rtouch /= 4095;
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#endif
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return rtouch;
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} else {
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#if !defined (__STM32F1__)
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return (1023-(z2-z1));
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#else
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return (4095-(z2-z1));
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#endif
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}
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}

‎STM32F1/libraries/Touch-Screen-Library_STM/TouchScreen_STM.h‎

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// Touch screen library with X Y and Z (pressure) readings as well
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// as oversampling to avoid 'bouncing'
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// (c) ladyada / adafruit
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// Code under MIT License
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// Ported to STM32 by Jaret Burkett https://github.com/jaretburkett
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#ifndef _ADAFRUIT_TOUCHSCREEN_STM_H_
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#define _ADAFRUIT_TOUCHSCREEN_STM_H_
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#include <stdint.h>
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class TSPoint {
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public:
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TSPoint(void);
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TSPoint(int16_t x, int16_t y, int16_t z);
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bool operator==(TSPoint);
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bool operator!=(TSPoint);
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int16_t x, y, z;
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};
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class TouchScreen {
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public:
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TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym);
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TouchScreen(uint8_t xp, uint8_t yp, uint8_t xm, uint8_t ym, uint16_t rx);
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bool isTouching(void);
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uint16_t pressure(void);
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int readTouchY();
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int readTouchX();
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TSPoint getPoint();
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int16_t pressureThreshhold;
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private:
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uint8_t _yp, _ym, _xm, _xp;
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uint16_t _rxplate;
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};
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#endif

‎STM32F1/libraries/Touch-Screen-Library_STM/examples/touchscreendemo/touchscreendemo.pde‎

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// Touch screen library with X Y and Z (pressure) readings as well
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// as oversampling to avoid 'bouncing'
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// This demo code returns raw readings, public domain
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#include <stdint.h>
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#include <TouchScreen_STM.h>
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#define YP 8 // must be an analog pin
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#define XM 9 // must be an analog pin
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#define YM 10 // can be a digital pin
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#define XP 11 // can be a digital pin
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// For better pressure precision, we need to know the resistance
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// between X+ and X- Use any multimeter to read it
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// For the one we're using, its 300 ohms across the X plate
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TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300);
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void setup(void) {
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Serial.begin(9600);
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}
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void loop(void) {
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// a point object holds x y and z coordinates
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TSPoint p = ts.getPoint();
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// we have some minimum pressure we consider 'valid'
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// pressure of 0 means no pressing!
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if (p.z > ts.pressureThreshhold) {
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Serial.print("X = "); Serial.print(p.x);
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Serial.print("\tY = "); Serial.print(p.y);
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Serial.print("\tPressure = "); Serial.println(p.z);
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}
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delay(100);
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}

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