Touch screen calibration sketch (work in progress)
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@ -14,6 +14,33 @@
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// Sizes!
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enum RA8875sizes { RA8875_480x272, RA8875_800x480 };
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// Touch screen cal structs
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typedef struct Point
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{
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int32_t x;
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int32_t y;
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} tsPoint_t;
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typedef struct Matrix
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{
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int32_t An,
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Bn,
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Cn,
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Dn,
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En,
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Fn,
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Divider ;
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} tsMatrix_t;
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typedef struct
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{
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uint32_t xraw; // Touch screen x
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uint32_t yraw; // Touch screen Y
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uint16_t xlcd; // LCD co-ordinate X
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uint16_t ylcd; // LCD co-ordinate Y
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bool valid; // Whether this is a valid reading or not
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} tsTouchData_t;
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class Adafruit_RA8875 : public Adafruit_GFX {
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public:
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Adafruit_RA8875(uint8_t cs, uint8_t rst);
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@ -0,0 +1,343 @@
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#include <SPI.h>
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#include "Adafruit_GFX.h"
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#include "Adafruit_RA8875.h"
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#define RA8875_INT 3
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#define RA8875_CS 10
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#define RA8875_RESET 9
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Adafruit_RA8875 tft = Adafruit_RA8875(RA8875_CS, RA8875_RESET);
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tsPoint_t _tsLCDPoints[3];
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tsPoint_t _tsTSPoints[3];
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tsMatrix_t _tsMatrix;
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/**************************************************************************/
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/*!
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@brief Calculates the difference between the touch screen and the
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actual screen co-ordinates, taking into account misalignment
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and any physical offset of the touch screen.
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@note This is based on the public domain touch screen calibration code
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written by Carlos E. Vidales (copyright (c) 2001).
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For more information, see the following app notes:
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- AN2173 - Touch Screen Control and Calibration
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Svyatoslav Paliy, Cypress Microsystems
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- Calibration in touch-screen systems
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Wendy Fang and Tony Chang,
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Analog Applications Journal, 3Q 2007 (Texas Instruments)
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*/
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/**************************************************************************/
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int setCalibrationMatrix( tsPoint_t * displayPtr, tsPoint_t * screenPtr, tsMatrix_t * matrixPtr)
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{
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int retValue = 0;
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matrixPtr->Divider = ((screenPtr[0].x - screenPtr[2].x) * (screenPtr[1].y - screenPtr[2].y)) -
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((screenPtr[1].x - screenPtr[2].x) * (screenPtr[0].y - screenPtr[2].y)) ;
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if( matrixPtr->Divider == 0 )
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{
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retValue = -1 ;
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}
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else
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{
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matrixPtr->An = ((displayPtr[0].x - displayPtr[2].x) * (screenPtr[1].y - screenPtr[2].y)) -
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((displayPtr[1].x - displayPtr[2].x) * (screenPtr[0].y - screenPtr[2].y)) ;
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matrixPtr->Bn = ((screenPtr[0].x - screenPtr[2].x) * (displayPtr[1].x - displayPtr[2].x)) -
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((displayPtr[0].x - displayPtr[2].x) * (screenPtr[1].x - screenPtr[2].x)) ;
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matrixPtr->Cn = (screenPtr[2].x * displayPtr[1].x - screenPtr[1].x * displayPtr[2].x) * screenPtr[0].y +
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(screenPtr[0].x * displayPtr[2].x - screenPtr[2].x * displayPtr[0].x) * screenPtr[1].y +
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(screenPtr[1].x * displayPtr[0].x - screenPtr[0].x * displayPtr[1].x) * screenPtr[2].y ;
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matrixPtr->Dn = ((displayPtr[0].y - displayPtr[2].y) * (screenPtr[1].y - screenPtr[2].y)) -
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((displayPtr[1].y - displayPtr[2].y) * (screenPtr[0].y - screenPtr[2].y)) ;
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matrixPtr->En = ((screenPtr[0].x - screenPtr[2].x) * (displayPtr[1].y - displayPtr[2].y)) -
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((displayPtr[0].y - displayPtr[2].y) * (screenPtr[1].x - screenPtr[2].x)) ;
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matrixPtr->Fn = (screenPtr[2].x * displayPtr[1].y - screenPtr[1].x * displayPtr[2].y) * screenPtr[0].y +
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(screenPtr[0].x * displayPtr[2].y - screenPtr[2].x * displayPtr[0].y) * screenPtr[1].y +
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(screenPtr[1].x * displayPtr[0].y - screenPtr[0].x * displayPtr[1].y) * screenPtr[2].y ;
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// Persist data to EEPROM
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_AN, matrixPtr->An);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_BN, matrixPtr->Bn);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_CN, matrixPtr->Cn);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_DN, matrixPtr->Dn);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_EN, matrixPtr->En);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_FN, matrixPtr->Fn);
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// eepromWriteS32(CFG_EEPROM_TOUCHSCREEN_CAL_DIVIDER, matrixPtr->Divider);
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// eepromWriteU8(CFG_EEPROM_TOUCHSCREEN_CALIBRATED, 1);
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}
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return( retValue ) ;
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}
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/**************************************************************************/
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/*!
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@brief Converts the supplied touch screen location (screenPtr) to
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a pixel location on the display (displayPtr) using the
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supplied matrix.
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@param[in] displayPtr Pointer to the tsPoint_t that will hold the
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compensated co-ordinates after calibration (the
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actual equivalent pixel location)
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@param[in] screenPtr Pointer to the tsPonint_t that contains the
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raw touch screen co-ordinated (pre-cal)
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@param[in] matrixPtr Pointer to the calibration matrix coefficients
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used during the calibration process (calculated
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via the tsCalibrate() helper function)
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@note This is based on the public domain touch screen calibration code
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written by Carlos E. Vidales (copyright (c) 2001).
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*/
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/**************************************************************************/
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int getDisplayPoint( tsPoint_t * displayPtr, tsPoint_t * screenPtr, tsMatrix_t * matrixPtr )
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{
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int retValue = 0 ;
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if( matrixPtr->Divider != 0 )
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{
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displayPtr->x = ( (matrixPtr->An * screenPtr->x) +
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(matrixPtr->Bn * screenPtr->y) +
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matrixPtr->Cn
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) / matrixPtr->Divider ;
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displayPtr->y = ( (matrixPtr->Dn * screenPtr->x) +
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(matrixPtr->En * screenPtr->y) +
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matrixPtr->Fn
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) / matrixPtr->Divider ;
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}
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else
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{
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return -1;
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}
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return( retValue );
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}
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/**************************************************************************/
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/*!
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@brief Waits for a touch event
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*/
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/**************************************************************************/
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void waitForTouchEvent(tsTouchData_t * touchData)
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{
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uint16_t tx, ty;
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/* Clear the touch data object and placeholder variables */
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memset(touchData, 0, sizeof(touchData));
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tx = ty = 0;
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/* Clear any previous interrupts to avoid false buffered reads */
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tft.touchRead(&tx, &ty);
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delay(1);
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/* Wait around for a new touch event (INT pin goes low) */
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while (digitalRead(RA8875_INT))
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{
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}
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/* Make sure this is really a touch event */
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if (tft.touched())
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{
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tft.touchRead(&tx, &ty);
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Serial.print("Touch: ");
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Serial.print(tx); Serial.print(", "); Serial.println(ty);
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touchData->xraw = tx;
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touchData->yraw = ty;
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touchData->valid = true;
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}
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else
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{
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touchData->valid = false;
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}
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}
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/**************************************************************************/
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/*!
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@brief Renders the calibration screen with an appropriately
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placed test point and waits for a touch event
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*/
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/**************************************************************************/
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tsTouchData_t tsRenderCalibrationScreen(uint16_t x, uint16_t y, uint16_t radius)
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{
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tft.fillScreen(RA8875_WHITE);
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tft.drawCircle(x, y, radius, RA8875_RED);
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tft.drawCircle(x, y, radius + 2, 0x8410); /* 50% Gray */
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// Wait for a valid touch events
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tsTouchData_t data;
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bool valid = false;
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while (!valid)
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{
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/* Keep polling until the TS event flag is valid */
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waitForTouchEvent(&data);
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valid = data.valid;
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}
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return data;
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}
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/**************************************************************************/
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/*!
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@brief Starts the screen calibration process. Each corner will be
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tested, meaning that each boundary (top, left, right and
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bottom) will be tested twice and the readings averaged.
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*/
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/**************************************************************************/
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void tsCalibrate(void)
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{
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tsTouchData_t data;
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/* --------------- Welcome Screen --------------- */
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Serial.println("Starting the calibration process");
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data = tsRenderCalibrationScreen(tft.width() / 2, tft.height() / 2, 5);
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delay(250);
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/* ----------------- First Dot ------------------ */
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// 10% over and 10% down
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data = tsRenderCalibrationScreen(tft.width() / 10, tft.height() / 10, 5);
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_tsLCDPoints[0].x = tft.width() / 10;
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_tsLCDPoints[0].y = tft.height() / 10;
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_tsTSPoints[0].x = data.xraw;
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_tsTSPoints[0].y = data.yraw;
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Serial.print("Point 1 - LCD");
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Serial.print(" X: ");
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Serial.print(_tsLCDPoints[0].x);
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Serial.print(" Y: ");
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Serial.print(_tsLCDPoints[0].y);
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Serial.print(" TS X: ");
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Serial.print(_tsTSPoints[0].x);
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Serial.print(" Y: ");
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Serial.println(_tsTSPoints[0].y);
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delay(750);
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/* ---------------- Second Dot ------------------ */
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// 50% over and 90% down
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data = tsRenderCalibrationScreen(tft.width() / 2, tft.height() - tft.height() / 10, 5);
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_tsLCDPoints[1].x = tft.width() / 2;
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_tsLCDPoints[1].y = tft.height() - tft.height() / 10;
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_tsTSPoints[1].x = data.xraw;
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_tsTSPoints[1].y = data.yraw;
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Serial.print("Point 2 - LCD");
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Serial.print(" X: ");
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Serial.print(_tsLCDPoints[1].x);
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Serial.print(" Y: ");
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Serial.print(_tsLCDPoints[1].y);
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Serial.print(" TS X: ");
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Serial.print(_tsTSPoints[1].x);
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Serial.print(" Y: ");
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Serial.println(_tsTSPoints[1].y);
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delay(750);
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/* ---------------- Third Dot ------------------- */
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// 90% over and 50% down
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data = tsRenderCalibrationScreen(tft.width() - tft.width() / 10, tft.height() / 2, 5);
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_tsLCDPoints[2].x = tft.width() - tft.width() / 10;
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_tsLCDPoints[2].y = tft.height() / 2;
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_tsTSPoints[2].x = data.xraw;
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_tsTSPoints[2].y = data.yraw;
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Serial.print("Point 3 - LCD");
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Serial.print(" X: ");
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Serial.print(_tsLCDPoints[2].x);
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Serial.print(" Y: ");
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Serial.print(_tsLCDPoints[2].y);
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Serial.print(" TS X: ");
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Serial.print(_tsTSPoints[2].x);
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Serial.print(" Y: ");
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Serial.println(_tsTSPoints[2].y);
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delay(750);
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/* Clear the screen */
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tft.fillScreen(RA8875_WHITE);
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// Do matrix calculations for calibration and store to EEPROM
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setCalibrationMatrix(&_tsLCDPoints[0], &_tsTSPoints[0], &_tsMatrix);
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}
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/**************************************************************************/
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/*!
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*/
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/**************************************************************************/
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void setup()
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{
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Serial.begin(9600);
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Serial.println("Hello, RA8875!");
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/* Initialise the display using 'RA8875_480x272' or 'RA8875_800x480' */
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if (!tft.begin(RA8875_480x272))
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{
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Serial.println("RA8875 not found ... check your wires!");
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while (1);
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}
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/* Enables the display and sets up the backlight */
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Serial.println("Found RA8875");
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tft.displayOn(true);
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tft.GPIOX(true); // Enable TFT - display enable tied to GPIOX
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tft.PWM1config(true, RA8875_PWM_CLK_DIV1024); // PWM output for backlight
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tft.PWM1out(255);
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/* Enable the touch screen */
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Serial.println("Enabled the touch screen");
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pinMode(RA8875_INT, INPUT);
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digitalWrite(RA8875_INT, HIGH);
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tft.touchEnable(true);
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// Try some GFX acceleration!
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//tft.drawCircle(100, 100, 50, RA8875_BLACK);
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//tft.fillCircle(100, 100, 49, RA8875_GREEN);
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//tft.drawPixel(10,10,RA8875_BLACK);
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//tft.drawPixel(11,11,RA8875_BLACK);
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//tft.drawRect(10, 10, 400, 200, RA8875_GREEN);
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//tft.fillRect(11, 11, 398, 198, RA8875_BLUE);
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//tft.drawLine(10, 10, 200, 100, RA8875_RED);
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tft.fillScreen(RA8875_WHITE);
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delay(100);
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/* Start the calibration process */
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tsCalibrate();
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/* _tsMatrix should now be populated with the correct coefficients! */
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Serial.println("Waiting for touch events ...");
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}
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/**************************************************************************/
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/*!
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*/
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/**************************************************************************/
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void loop()
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{
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tsTouchData_t data = { 0 };
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waitForTouchEvent(&data);
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/* Calcuate the real X/Y position based on the calibration matrix */
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tsPoint_t raw = { data.xraw, data.yraw }; /* Raw TS co-ordinates */
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tsPoint_t calibrated = { 0, 0 }; /* Placeholder for calibrated co-ordinates */
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Serial.print("Raw: ");
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Serial.print(raw.x);
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Serial.print(", ");
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Serial.print(raw.y);
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Serial.println("");
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getDisplayPoint(&calibrated, &raw, &_tsMatrix );
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Serial.print("Cal: ");
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Serial.print(calibrated.x);
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Serial.print(", ");
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Serial.print(calibrated.y);
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Serial.println("");
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/* Draw a single pixel at the calibrated point */
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tft.fillCircle(calibrated.x, calibrated.y, 3, RA8875_BLACK);
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}
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