Add XPT2046 touch controller support

supports esp8266 + RPi displays

TFT_eSPI.cpp

@@ -73,6 +73,12 @@ TFT_eSPI::TFT_eSPI(int16_t w, int16_t h)
   pinMode(TFT_CS, OUTPUT);
 #endif
 
+// Configure chip select for touchscreen controller if present
+#ifdef TOUCH_CS
+  digitalWrite(TOUCH_CS, HIGH); // Chip select high (inactive)
+  pinMode(TOUCH_CS, OUTPUT);
+#endif
+
 #ifdef TFT_WR
   digitalWrite(TFT_WR, HIGH); // Set write strobe high (inactive)
   pinMode(TFT_WR, OUTPUT);
@@ -3641,6 +3647,149 @@ void spiWriteBlock(uint16_t color, uint32_t repeat)
 }
 #endif
 
+
+/***************************************************************************************
+** Function name:           getTouchRaw
+** Description:             read raw position of touchpad if pressed. Return false if not pressed. 
+***************************************************************************************/
+#ifdef TOUCH_CS
+
+uint8_t TFT_eSPI::getTouchRaw(uint16_t *x, uint16_t *y){
+  uint16_t tmp;
+  CS_H;
+  T_CS_L;
+  
+  SPI.setFrequency(SPI_TOUCH_FREQUENCY);
+
+  // Start bit + YP sample request for x position
+  tmp = SPI.transfer(0xd0);
+  tmp = SPI.transfer(0);
+  tmp = tmp <<5;
+  tmp |= 0x1f & (SPI.transfer(0)>>3);
+
+  if(tmp == 0 || tmp == 0x3ff){
+    T_CS_H;
+    SPI.setFrequency(SPI_FREQUENCY);
+    return false;
+    }
+
+  *x = tmp;
+
+  // Start bit + XP sample request for y position
+  SPI.transfer(0x90);
+  tmp = SPI.transfer(0);
+  tmp = tmp <<5;
+  tmp |= 0x1f & (SPI.transfer(0)>>3);
+
+  *y = tmp;
+
+  T_CS_H;
+  SPI.setFrequency(SPI_FREQUENCY);
+
+  if(tmp == 0 || tmp == 0x3ff){
+    return false;
+    }
+  return true;
+}
+
+/***************************************************************************************
+** Function name:           getTouch
+** Description:             read callibrated position of touchpad if pressed. Return false if not pressed. 
+***************************************************************************************/
+uint8_t TFT_eSPI::getTouch(uint16_t *x, uint16_t *y){
+  uint8_t retVal;
+  uint16_t x_tmp, y_tmp;
+  
+  retVal = getTouchRaw(&x_tmp,&y_tmp);
+  if(!retVal)
+    return retVal;
+
+  *x=(x_tmp-touchCalibration_x0)*_width/(touchCalibration_x1-touchCalibration_x0);
+  *y=(y_tmp-touchCalibration_y0)*_height/(touchCalibration_y1-touchCalibration_y0);
+
+  return retVal;
+}
+
+/***************************************************************************************
+** Function name:           calibrateTouch
+** Description:             generates calibration data for touchscreen. 
+***************************************************************************************/
+uint8_t TFT_eSPI::calibrateTouch(uint16_t *data, uint32_t color_bg, uint32_t color_fg, uint8_t size){
+  uint16_t values[] = {0,0,0,0,0,0,0,0};
+  uint16_t x_tmp, y_tmp;
+
+
+  for(uint8_t i = 0; i<4; i++){
+    fillRect(0, 0, size+1, size+1, color_bg);
+    fillRect(0, _height-size-1, size+1, size+1, color_bg);
+    fillRect(_width-size-1, 0, size+1, size+1, color_bg);
+    fillRect(_width-size-1, _height-size-1, size+1, size+1, color_bg);
+
+    if (i == 5) break; // used to clear the arrows
+    
+    switch (i) {
+      case 0: // up left
+        drawLine(0, 0, 0, size, color_fg);
+        drawLine(0, 0, size, 0, color_fg);
+        drawLine(0, 0, size , size, color_fg);
+        break;
+      case 1: // bot left
+        drawLine(0, _height-size-1, 0, _height-1, color_fg);
+        drawLine(0, _height-1, size, _height-1, color_fg);
+        drawLine(size, _height-size-1, 0, _height-1 , color_fg);
+        break;
+      case 2: // up right
+        drawLine(_width-size-1, 0, _width-1, 0, color_fg);
+        drawLine(_width-size-1, size, _width-1, 0, color_fg);
+        drawLine(_width-1, size, _width-1, 0, color_fg);
+        break;
+      case 3: // bot right
+        drawLine(_width-size-1, _height-size-1, _width-1, _height-1, color_fg);
+        drawLine(_width-1, _height-1-size, _width-1, _height-1, color_fg);
+        drawLine(_width-1-size, _height-1, _width-1, _height-1, color_fg);
+        break;
+      }
+
+    // user has to get the chance to release
+    if(i>0) delay(1000);
+
+    for(uint8_t j= 0; j<8; j++){
+      while(!getTouchRaw(&x_tmp, &y_tmp)) delay(100);
+      values[i*2  ] += x_tmp;
+      values[i*2+1] += y_tmp;
+      }
+    values[i*2  ] /= 8;
+    values[i*2+1] /= 8;
+  }
+
+  // TODO: build in orientation check!
+  touchCalibration_x0 = (values[0] + values[2])/2; // calc min x
+  touchCalibration_x1 = (values[4] + values[6])/2; // calc max x
+  touchCalibration_y0 = (values[1] + values[5])/2; // calc min y
+  touchCalibration_y1 = (values[3] + values[7])/2; // calc max y
+
+  if(data != NULL){
+    data[0] = touchCalibration_x0;
+    data[1] = touchCalibration_x1;
+    data[2] = touchCalibration_y0;
+    data[3] = touchCalibration_y1;
+    }
+}
+
+
+/***************************************************************************************
+** Function name:           setTouch
+** Description:             imports calibration data for touchscreen. 
+***************************************************************************************/
+void TFT_eSPI::setTouch(uint16_t *data){
+  touchCalibration_x0 = data[0];
+  touchCalibration_x1 = data[1];
+  touchCalibration_y0 = data[2];
+  touchCalibration_y1 = data[3];
+}
+
+#endif
+
 /***************************************************
   The majority of code in this file is "FunWare", the only condition of use of
   those portions is that users have fun!  Most of the effort has been spent on