File content as of revision 79:544eb4964795:

/// This file contains the RA8875 Touch panel methods.
///

#include "RA8875.h"

// ### Touch Panel support code additions begin here

RetCode_t RA8875::TouchPanelInit(void)
{
    //TPCR0: Set enable bit, default sample time, wakeup, and ADC clock
    WriteCommand(TPCR0, TP_ENABLE | TP_ADC_SAMPLE_DEFAULT_CLKS | TP_ADC_CLKDIV_DEFAULT);
    // TPCR1: Set auto/manual, Ref voltage, debounce, manual mode params
    WriteCommand(TPCR1, TP_MODE_DEFAULT | TP_DEBOUNCE_DEFAULT);
    WriteCommand(INTC1, ReadCommand(INTC1) | RA8875_INT_TP);        // reg INTC1: Enable Touch Panel Interrupts (D2 = 1)
    WriteCommand(INTC2, RA8875_INT_TP);                            // reg INTC2: Clear any TP interrupt flag
    return noerror;
}

RetCode_t RA8875::TouchPanelInit(uint8_t bTpEnable, uint8_t bTpAutoManual, uint8_t bTpDebounce, uint8_t bTpManualMode, uint8_t bTpAdcClkDiv, uint8_t bTpAdcSampleTime)
{
    // Parameter bounds check
    if( \
            !(bTpEnable == TP_ENABLE || bTpEnable == TP_ENABLE) || \
            !(bTpAutoManual == TP_MODE_AUTO || bTpAutoManual == TP_MODE_MANUAL) || \
            !(bTpDebounce == TP_DEBOUNCE_OFF || bTpDebounce == TP_DEBOUNCE_ON) || \
            !(bTpManualMode <= TP_MANUAL_LATCH_Y) || \
            !(bTpAdcClkDiv <= TP_ADC_CLKDIV_128) || \
            !(bTpAdcSampleTime <= TP_ADC_SAMPLE_65536_CLKS) \
      ) return bad_parameter;
    // Construct the config byte for TPCR0 and write them
    WriteCommand(TPCR0, bTpEnable | bTpAdcClkDiv | bTpAdcSampleTime);    // Note: Wakeup is never enabled
    // Construct the config byte for TPCR1 and write them
    WriteCommand(TPCR1, bTpManualMode | bTpDebounce | bTpManualMode);    // Note: Always uses internal Vref.
    // Set up the interrupt flag and enable bits
    WriteCommand(INTC1, ReadCommand(INTC1) | RA8875_INT_TP);        // reg INTC1: Enable Touch Panel Interrupts (D2 = 1)
    WriteCommand(INTC2, RA8875_INT_TP);                            // reg INTC2: Clear any TP interrupt flag
    return noerror;
}

bool RA8875::TouchPanelA2DFiltered(loc_t *x, loc_t *y)
{
    unsigned char touchready;
    static int xbuf[TPBUFSIZE], ybuf[TPBUFSIZE], sample = 0;
    int i, j, temp;

    if( (ReadCommand(INTC2) & RA8875_INT_TP) ) {        // Test for TP Interrupt pending in register INTC2
        // Get the next data samples
        ybuf[sample] =  ReadCommand(TPYH) << 2 | ( (ReadCommand(TPXYL) & 0xC) >> 2 );   // D[9:2] from reg TPYH, D[1:0] from reg TPXYL[3:2]
        xbuf[sample] =  ReadCommand(TPXH) << 2 | ( (ReadCommand(TPXYL) & 0x3)      );   // D[9:2] from reg TPXH, D[1:0] from reg TPXYL[1:0]
        // Check for a complete set
        if(++sample == TPBUFSIZE) {
            // Buffers are full, so process them using Finn's method described in Analog Dialogue No. 44, Feb 2010
            // This requires sorting the samples in order of size, then discarding the top 25% and
            //   bottom 25% as noise spikes. Finally, the middle 50% of the values are averaged to
            //   reduce Gaussian noise.

            // Sort the Y buffer using an Insertion Sort
            for(i = 1; i <= TPBUFSIZE; i++) {
                temp = ybuf[i];
                j = i;
                while( j && (ybuf[j-1] > temp) ) {
                    ybuf[j] = ybuf[j-1];
                    j = j-1;
                }
                ybuf[j] = temp;
            } // End of Y sort
            // Sort the X buffer the same way
            for(i = 1; i <= TPBUFSIZE; i++) {
                temp = xbuf[i];
                j = i;
                while( j && (xbuf[j-1] > temp) ) {
                    xbuf[j] = xbuf[j-1];
                    j = j-1;
                }
                xbuf[j] = temp;
            } // End of X sort
            // Average the middle half of the  Y values and report them
            j = 0;
            for(i = (TPBUFSIZE/4) - 1; i < TPBUFSIZE - TPBUFSIZE/4; i++ ) {
                j += ybuf[i];
            }
            *y = j * (float)2/TPBUFSIZE;    // This is the average
            // Average the middle half of the  X values and report them
            j = 0;
            for(i = (TPBUFSIZE/4) - 1; i < TPBUFSIZE - TPBUFSIZE/4; i++ ) {
                j += xbuf[i];
            }
            *x = j * (float)2/TPBUFSIZE;    // This is the average
            // Tidy up and return
            touchready = 1;
            sample = 0;             // Ready to start on the next set of data samples
        } else {
            // Buffer not yet full, so do not return any results yet
            touchready = 0;
        }
        WriteCommand(INTC2, RA8875_INT_TP);            // reg INTC2: Clear that TP interrupt flag
    } // End of initial if -- data has been read and processed
    else
        touchready = 0;         // Touch Panel "Int" was not set
    return touchready;
}

bool RA8875::TouchPanelA2DRaw(loc_t *x, loc_t *y)
{
    unsigned char touchready;

    if( (ReadCommand(INTC2) & RA8875_INT_TP) ) {        // Test for TP Interrupt pending in register INTC2
        *y =  ReadCommand(TPYH) << 2 | ( (ReadCommand(TPXYL) & 0xC) >> 2 );   // D[9:2] from reg TPYH, D[1:0] from reg TPXYL[3:2]
        *x =  ReadCommand(TPXH) << 2 | ( (ReadCommand(TPXYL) & 0x3)      );   // D[9:2] from reg TPXH, D[1:0] from reg TPXYL[1:0]
        WriteCommand(INTC2, RA8875_INT_TP);            // reg INTC2: Clear that TP interrupt flag
        touchready = 1;
    } else
        touchready = 0;
    return touchready;
}

/*   The following section is derived from Carlos E. Vidales.
 *
 *   Copyright (c) 2001, Carlos E. Vidales. All rights reserved.
 *
 *   This sample program was written and put in the public domain 
 *    by Carlos E. Vidales.  The program is provided "as is" 
 *    without warranty of any kind, either expressed or implied.
 *   If you choose to use the program within your own products
 *    you do so at your own risk, and assume the responsibility
 *    for servicing, repairing or correcting the program should
 *    it prove defective in any manner.
 *   You may copy and distribute the program's source code in any 
 *    medium, provided that you also include in each copy an
 *    appropriate copyright notice and disclaimer of warranty.
 *   You may also modify this program and distribute copies of
 *    it provided that you include prominent notices stating 
 *    that you changed the file(s) and the date of any change,
 *    and that you do not charge any royalties or licenses for 
 *    its use.
 * 
 *   This file contains functions that implement calculations 
 *    necessary to obtain calibration factors for a touch screen
 *    that suffers from multiple distortion effects: namely, 
 *    translation, scaling and rotation.
 *
 *   The following set of equations represent a valid display 
 *    point given a corresponding set of touch screen points:
 *
 *                                              /-     -\
 *              /-    -\     /-            -\   |       |
 *              |      |     |              |   |   Xs  |
 *              |  Xd  |     | A    B    C  |   |       |
 *              |      |  =  |              | * |   Ys  |
 *              |  Yd  |     | D    E    F  |   |       |
 *              |      |     |              |   |   1   |
 *              \-    -/     \-            -/   |       |
 *                                              \-     -/
 *    where:
 *           (Xd,Yd) represents the desired display point 
 *                    coordinates,
 *           (Xs,Ys) represents the available touch screen
 *                    coordinates, and the matrix
 *           /-   -\
 *           |A,B,C|
 *           |D,E,F| represents the factors used to translate
 *           \-   -/  the available touch screen point values
 *                    into the corresponding display 
 *                    coordinates.
 *    Note that for practical considerations, the utilities 
 *     within this file do not use the matrix coefficients as
 *     defined above, but instead use the following 
 *     equivalents, since floating point math is not used:
 *            A = An/Divider 
 *            B = Bn/Divider 
 *            C = Cn/Divider 
 *            D = Dn/Divider 
 *            E = En/Divider 
 *            F = Fn/Divider 
 *    The functions provided within this file are:
 *          setCalibrationMatrix() - calculates the set of factors
 *                                    in the above equation, given
 *                                    three sets of test points.
 *               getDisplayPoint() - returns the actual display
 *                                    coordinates, given a set of
 *                                    touch screen coordinates.
 * translateRawScreenCoordinates() - helper function to transform
 *                                    raw screen points into values
 *                                    scaled to the desired display
 *                                    resolution.
 */

/**********************************************************************
 *
 *     Function: setCalibrationMatrix()
 *
 *  Description: Calling this function with valid input data
 *                in the display and screen input arguments 
 *                causes the calibration factors between the
 *                screen and display points to be calculated,
 *                and the output argument - matrixPtr - to be 
 *                populated.
 *
 *               This function needs to be called only when new
 *                calibration factors are desired.
 *               
 *  
 *  Argument(s): displayPtr (input) - Pointer to an array of three 
 *                                     sample, reference points.
 *               screenPtr (input) - Pointer to the array of touch 
 *                                    screen points corresponding 
 *                                    to the reference display points.
 *               matrixPtr (output) - Pointer to the calibration 
 *                                     matrix computed for the set 
 *                                     of points being provided.
 *
 *
 *  From the article text, recall that the matrix coefficients are
 *   resolved to be the following:
 *
 *
 *      Divider =  (Xs0 - Xs2)*(Ys1 - Ys2) - (Xs1 - Xs2)*(Ys0 - Ys2)
 *
 *
 *
 *                 (Xd0 - Xd2)*(Ys1 - Ys2) - (Xd1 - Xd2)*(Ys0 - Ys2)
 *            A = ---------------------------------------------------
 *                                   Divider
 *
 *
 *                 (Xs0 - Xs2)*(Xd1 - Xd2) - (Xd0 - Xd2)*(Xs1 - Xs2)
 *            B = ---------------------------------------------------
 *                                   Divider
 *
 *
 *                 Ys0*(Xs2*Xd1 - Xs1*Xd2) + 
 *                             Ys1*(Xs0*Xd2 - Xs2*Xd0) + 
 *                                           Ys2*(Xs1*Xd0 - Xs0*Xd1)
 *            C = ---------------------------------------------------
 *                                   Divider
 *
 *
 *                 (Yd0 - Yd2)*(Ys1 - Ys2) - (Yd1 - Yd2)*(Ys0 - Ys2)
 *            D = ---------------------------------------------------
 *                                   Divider
 *
 *
 *                 (Xs0 - Xs2)*(Yd1 - Yd2) - (Yd0 - Yd2)*(Xs1 - Xs2)
 *            E = ---------------------------------------------------
 *                                   Divider
 *
 *
 *                 Ys0*(Xs2*Yd1 - Xs1*Yd2) + 
 *                             Ys1*(Xs0*Yd2 - Xs2*Yd0) + 
 *                                           Ys2*(Xs1*Yd0 - Xs0*Yd1)
 *            F = ---------------------------------------------------
 *                                   Divider
 *
 *
 *       Return: OK - the calibration matrix was correctly 
 *                     calculated and its value is in the 
 *                     output argument.
 *               NOT_OK - an error was detected and the 
 *                         function failed to return a valid
 *                         set of matrix values.
 *                        The only time this sample code returns
 *                        NOT_OK is when Divider == 0
 *
 *
 *
 *                 NOTE!    NOTE!    NOTE!
 *
 *  setCalibrationMatrix() and getDisplayPoint() will do fine
 *  for you as they are, provided that your digitizer         
 *  resolution does not exceed 10 bits (1024 values).  Higher
 *  resolutions may cause the integer operations to overflow
 *  and return incorrect values.  If you wish to use these   
 *  functions with digitizer resolutions of 12 bits (4096    
 *  values) you will either have to a) use 64-bit signed     
 *  integer variables and math, or b) judiciously modify the 
 *  operations to scale results by a factor of 2 or even 4.  
 *
 */
RetCode_t RA8875::TouchPanelCalibrate(point_t * displayPtr, point_t * screenPtr, tpMatrix_t * matrixPtr)
{
    RetCode_t retValue = noerror;

    tpMatrix.Divider = ((screenPtr[0].x - screenPtr[2].x) * (screenPtr[1].y - screenPtr[2].y)) -
                       ((screenPtr[1].x - screenPtr[2].x) * (screenPtr[0].y - screenPtr[2].y)) ;

    if( tpMatrix.Divider == 0 )  {
        retValue = bad_parameter;
    }  else   {
        tpMatrix.An = ((displayPtr[0].x - displayPtr[2].x) * (screenPtr[1].y - screenPtr[2].y)) -
                      ((displayPtr[1].x - displayPtr[2].x) * (screenPtr[0].y - screenPtr[2].y)) ;

        tpMatrix.Bn = ((screenPtr[0].x - screenPtr[2].x) * (displayPtr[1].x - displayPtr[2].x)) -
                      ((displayPtr[0].x - displayPtr[2].x) * (screenPtr[1].x - screenPtr[2].x)) ;

        tpMatrix.Cn = (screenPtr[2].x * displayPtr[1].x - screenPtr[1].x * displayPtr[2].x) * screenPtr[0].y +
                      (screenPtr[0].x * displayPtr[2].x - screenPtr[2].x * displayPtr[0].x) * screenPtr[1].y +
                      (screenPtr[1].x * displayPtr[0].x - screenPtr[0].x * displayPtr[1].x) * screenPtr[2].y ;

        tpMatrix.Dn = ((displayPtr[0].y - displayPtr[2].y) * (screenPtr[1].y - screenPtr[2].y)) -
                      ((displayPtr[1].y - displayPtr[2].y) * (screenPtr[0].y - screenPtr[2].y)) ;

        tpMatrix.En = ((screenPtr[0].x - screenPtr[2].x) * (displayPtr[1].y - displayPtr[2].y)) -
                      ((displayPtr[0].y - displayPtr[2].y) * (screenPtr[1].x - screenPtr[2].x)) ;

        tpMatrix.Fn = (screenPtr[2].x * displayPtr[1].y - screenPtr[1].x * displayPtr[2].y) * screenPtr[0].y +
                      (screenPtr[0].x * displayPtr[2].y - screenPtr[2].x * displayPtr[0].y) * screenPtr[1].y +
                      (screenPtr[1].x * displayPtr[0].y - screenPtr[0].x * displayPtr[1].y) * screenPtr[2].y ;
        if (matrixPtr)
            memcpy(matrixPtr, &tpMatrix, sizeof(tpMatrix_t));
    }
    return( retValue ) ;
}

/**********************************************************************
 *
 *     Function: getDisplayPoint()
 *
 *  Description: Given a valid set of calibration factors and a point
 *                value reported by the touch screen, this function
 *                calculates and returns the true (or closest to true)
 *                display point below the spot where the touch screen 
 *                was touched.
 * 
 *
 * 
 *  Argument(s): displayPtr (output) - Pointer to the calculated
 *                                      (true) display point.
 *               screenPtr (input) - Pointer to the reported touch
 *                                    screen point.
 *               matrixPtr (input) - Pointer to calibration factors
 *                                    matrix previously calculated
 *                                    from a call to 
 *                                    setCalibrationMatrix()
 * 
 *
 *  The function simply solves for Xd and Yd by implementing the 
 *   computations required by the translation matrix.  
 * 
 *                                              /-     -\
 *              /-    -\     /-            -\   |       |
 *              |      |     |              |   |   Xs  |
 *              |  Xd  |     | A    B    C  |   |       |
 *              |      |  =  |              | * |   Ys  |
 *              |  Yd  |     | D    E    F  |   |       |
 *              |      |     |              |   |   1   |
 *              \-    -/     \-            -/   |       |
 *                                              \-     -/
 * 
 *  It must be kept brief to avoid consuming CPU cycles.
 *
 *       Return: OK - the display point was correctly calculated 
 *                     and its value is in the output argument.
 *               NOT_OK - an error was detected and the function
 *                         failed to return a valid point.
 *
 *                 NOTE!    NOTE!    NOTE!
 *
 *  setCalibrationMatrix() and getDisplayPoint() will do fine
 *  for you as they are, provided that your digitizer         
 *  resolution does not exceed 10 bits (1024 values).  Higher
 *  resolutions may cause the integer operations to overflow
 *  and return incorrect values.  If you wish to use these   
 *  functions with digitizer resolutions of 12 bits (4096    
 *  values) you will either have to a) use 64-bit signed     
 *  integer variables and math, or b) judiciously modify the 
 *  operations to scale results by a factor of 2 or even 4.  
 *
 */
bool RA8875::TouchPanelReadable(point_t * TouchPoint)
{
    bool touched = false;
    point_t screenpoint = {0, 0};
    
    if (TouchPanelA2DFiltered(&screenpoint.x, &screenpoint.y)) {
        touched = true;
        if (tpMatrix.Divider != 0 && TouchPoint) {
            /* Operation order is important since we are doing integer */
            /*  math. Make sure you add all terms together before      */
            /*  dividing, so that the remainder is not rounded off     */
            /*  prematurely.                                           */
            TouchPoint->x = ( (tpMatrix.An * screenpoint.x) +
                              (tpMatrix.Bn * screenpoint.y) +
                              tpMatrix.Cn
                            ) / tpMatrix.Divider ;

            TouchPoint->y = ( (tpMatrix.Dn * screenpoint.x) +
                              (tpMatrix.En * screenpoint.y) +
                              tpMatrix.Fn
                            ) / tpMatrix.Divider ;
        } else {
            touched = false;
        }
    }
    return touched;
}


RetCode_t RA8875::TouchPanelSetMatrix(tpMatrix_t * matrixPtr)
{
    if (matrixPtr == NULL || matrixPtr->Divider == 0)
        return bad_parameter;
    memcpy(&tpMatrix, matrixPtr, sizeof(tpMatrix_t));
    return noerror;
}

// #### end of touch panel code additions