touch_tft.cpp

00001 /* mbed library for resistive touch pads
00002  * uses 4 pins - 2 IO and 2 Analog
00003 
00004  * c 2011 Peter Drescher - DC2PD
00005  *
00006  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00007  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00008  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00009  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00010  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00011  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00012  * THE SOFTWARE.
00013  */
00014 
00015 
00016 #include "touch_tft.h"
00017 #include "mbed.h"
00018 
00019 #define threshold 0x2000  // threshold to detect pressed 
00020 
00021 touch_tft::touch_tft(PinName xp, PinName xm, PinName yp, PinName ym,
00022                      PinName mosi, PinName miso, PinName sclk, PinName cs, PinName reset,const char* name):
00023         _xp(xp),_xm(xm),_yp(yp),_ym(ym),_ax(xp),_ay(yp),
00024         SPI_TFT(mosi,miso,sclk,cs,reset,name) {
00025     xa = xp;
00026     ya = yp;
00027 
00028 }
00029 
00030 point touch_tft::get_touch() {
00031     unsigned short x1 = 0,x2 = 0, y1 = 0, y2 = 0;
00032     unsigned int s1 = 0,s2 = 0,d1 , d2;
00033     point p;
00034 
00035     do {
00036         // read y voltage
00037         _xp.output();
00038         _xm.output();
00039         switch (orientation) {
00040             case(0):
00041             case(3):
00042                 _xp = 1;
00043                 _xm = 0;
00044                 break;
00045             case(1):
00046             case(2):
00047                 _xp = 0;
00048                 _xm = 1;
00049                 break;
00050         }
00051         _ym.input();        // y- have to be passive
00052         AnalogIn Ay(ya);    // we have to call the constructor to switch to analog mode
00053         wait_us(10);
00054         y1 = Ay.read_u16(); // get y voltage
00055         d1 = (y1 > y2)? (y1-y2) : (y2-y1);
00056         if (((y1 < 8000) && (d1 < 2000)) || ((y1 > 8000) && (d1 < 150))) s1 ++;
00057         else {
00058             if (s1 > 0) s1 --;
00059         }
00060         y2 = y1;
00061         // debug
00062         //locate(1,7);
00063         //printf("d: %4d y: %5d s1: %4d",d1,y1,s1);
00064 
00065         // read x voltage
00066         _yp.output();
00067         _ym.output();
00068         switch (orientation) {
00069             case(0):
00070             case(1):
00071                 _yp = 1;
00072                 _ym = 0;
00073                 break;
00074             case(2):
00075             case(3):
00076                 _yp = 0;
00077                 _ym = 1;
00078                 break;
00079         }
00080         _xm.input();        // x- have to be passive
00081         AnalogIn Ax(xa);    // we have to call the constructor to switch to analog mode
00082         wait_us(10);
00083         x1 = Ax.read_u16(); // get x voltage
00084         d2 = (x1 > x2)? (x1-x2) : (x2-x1);
00085         if (((x1 < 8000) && (d2 < 2000)) || ((x1 > 8000) && (d2 < 150))) s2 ++;
00086         else {
00087             if (s2 > 0) s2 --;
00088         }
00089         x2 = x1;
00090         // debug
00091         //locate(1,8);
00092         //printf("d: %4d x: %5d s2: %4d",d2,x1,s2);
00093 
00094     } while (s1 < 3 || s2 < 3); // read until we have three samples close together
00095     switch (orientation) {
00096         case(0):
00097         case(2):
00098             p.y = (x1+x2) / 2;  // average of two sample
00099             p.x = (y1+y2) / 2;
00100             break;
00101         case(1):
00102         case(3):
00103             p.x = (x1+x2) / 2;  // average of two sample
00104             p.y = (y1+y2) / 2;
00105             break;
00106     }
00107     return(p);
00108 }
00109 
00110 void touch_tft::calibrate(void) {
00111     int i;
00112     int a = 0,b = 0,c = 0, d = 0;
00113     int pos_x, pos_y;
00114     point p;
00115 
00116     cls();
00117     line(0,3,6,3,White);
00118     line(3,0,3,6,White);
00119 
00120     // get the center of the screen
00121     pos_x = columns() / 2 - 3;
00122     pos_x = pos_x * font[1];
00123     pos_y = (rows() / 2) - 1;
00124     pos_y = pos_y * font[2];
00125 
00126     locate(pos_x,pos_y);
00127     printf("press cross");
00128     locate(pos_x,pos_y + font[2]);
00129     printf("to calibrate");
00130     for (i=0; i<5; i++) {
00131         do {
00132             p = get_touch();
00133         } while (p.x < 0x2000 | p.y < 0x2000);  // wait for touch
00134         a += p.x;
00135         b += p.y;
00136     }
00137     a = a / 5;
00138     b = b / 5;
00139     locate(pos_x,pos_y);
00140     printf("OK         ");
00141     do {
00142         p = get_touch();
00143     } while (p.y > 0x2000 | p.x > 0x2000); // wait for no touch
00144 
00145     cls();
00146     line(width() -5, height() - 8,width() - 5,height() -1,White);   // paint cross
00147     line(width() - 8,height() - 5,width() - 1,height() - 5,White);
00148     locate(pos_x,pos_y);
00149     printf("press cross");
00150     locate(pos_x,pos_y + font[2]);
00151     printf("to calibrate");
00152     for (i=0; i<5; i++) {
00153         do {
00154             p  = get_touch();
00155         } while (p.y < 0x2000 | p.x < 0x2000);  // wait for touch
00156         c+= p.x;
00157         d+= p.y;
00158     }
00159     c = c / 5;
00160     d = d / 5;
00161 
00162     locate(pos_x, pos_y);
00163     printf("OK         ");
00164     do {
00165         p = get_touch();
00166     } while (p.y > 0x2000 | p.x > 0x2000); // wait for no touch
00167 
00168     cls();
00169 
00170     x_off = a;
00171     y_off = b;
00172 
00173     i = c-a;  // delta x
00174     pp_tx = i / (width() - 6);
00175 
00176     i = d-b;  // delta y
00177     pp_ty = i / (height() - 6);
00178 }
00179 
00180 
00181 point touch_tft::to_pixel(point a_point) {
00182     point p;
00183 
00184     p.x = (a_point.x - x_off) / pp_tx;
00185     if (p.x > width()) p.x = width();
00186     p.y = (a_point.y - y_off) / pp_ty;
00187     if (p.y > height()) p.y = height();
00188     return (p);
00189 }
00190 
00191 bool touch_tft::is_touched(point a) {
00192     if (a.x > threshold & a.y > threshold) return(true);
00193     else return(false);
00194 }