Diff: TSC2046.cpp

Revision:

0:0fdadbc3d852

Child:

4:b32cf4ef45c5

diff -r 000000000000 -r 0fdadbc3d852 TSC2046.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TSC2046.cpp	Thu Sep 26 06:37:02 2013 +0000
@@ -0,0 +1,617 @@
+
+#include "mbed.h"
+#include "TSC2046.h"
+
+#ifndef ABS
+#define ABS(x) (  ((int32_t)(x)) < 0 ? (-(x)) : (x))
+#endif
+
+#define ADS_START         (1 << 7)
+#define ADS_A2A1A0_d_y    (1 << 4)  /* differential */
+#define ADS_A2A1A0_d_z1   (3 << 4)  /* differential */
+#define ADS_A2A1A0_d_z2   (4 << 4)  /* differential */
+#define ADS_A2A1A0_d_x    (5 << 4)  /* differential */
+#define ADS_A2A1A0_temp0  (0 << 4)  /* non-differential */
+#define ADS_A2A1A0_vbatt  (2 << 4)  /* non-differential */
+#define ADS_A2A1A0_vaux   (6 << 4)  /* non-differential */
+#define ADS_A2A1A0_temp1  (7 << 4)  /* non-differential */
+#define ADS_8_BIT         (1 << 3)
+#define ADS_12_BIT        (0 << 3)
+#define ADS_SER           (1 << 2)  /* non-differential */
+#define ADS_DFR           (0 << 2)  /* differential */
+#define ADS_PD10_PDOWN    (0 << 0)  /* lowpower mode + penirq */
+#define ADS_PD10_ADC_ON   (1 << 0)  /* ADC on */
+#define ADS_PD10_REF_ON   (2 << 0)  /* vREF on + penirq */
+#define ADS_PD10_ALL_ON   (3 << 0)  /* ADC + vREF on */
+
+
+#define READ_12BIT_DFR(d, adc, vref) (ADS_START | d \
+  | ADS_12_BIT | ADS_DFR | \
+  (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
+
+#define READ_Y(vref)  (READ_12BIT_DFR(ADS_A2A1A0_d_y,  1, vref))
+#define READ_Z1(vref) (READ_12BIT_DFR(ADS_A2A1A0_d_z1, 1, vref))
+#define READ_Z2(vref) (READ_12BIT_DFR(ADS_A2A1A0_d_z2, 1, vref))
+#define READ_X(vref)  (READ_12BIT_DFR(ADS_A2A1A0_d_x,  1, vref))
+#define PWRDOWN       (READ_12BIT_DFR(ADS_A2A1A0_d_y,  0, 0))  /* LAST */
+
+/* single-ended samples need to first power up reference voltage;
+ * we leave both ADC and VREF powered
+ */
+#define READ_12BIT_SER(x) (ADS_START | x \
+  | ADS_12_BIT | ADS_SER)
+
+#define REF_ON  (READ_12BIT_DFR(ADS_A2A1A0_d_x, 1, 1))
+#define REF_OFF (READ_12BIT_DFR(ADS_A2A1A0_d_y, 0, 0))
+
+#define DEBOUNCE_MAX 10
+#define DEBOUNCE_TOL  3
+
+TSC2046::TSC2046(PinName mosi, PinName miso, PinName sck, PinName cs) :
+_spi(mosi, miso, sck), _cs(cs)
+{
+    _cs = 1; // active low
+
+    _spi.format(8, 3);
+    _spi.frequency(1500000);
+    _calibrated = false;
+    _initialized = false;
+}
+
+
+void TSC2046::read(touchCoordinate_t &coord) {
+
+    touchCoordinate_t tmpCoord;
+    calibPoint_t displayPoint;
+    calibPoint_t screenSample;
+
+    if (!_initialized) {
+        init();
+        _initialized = true;
+    }
+
+    readAndFilter(tmpCoord);
+
+    _cs = 0;
+    _spi.write(PWRDOWN);
+    _cs = 1;
+
+    coord.z = tmpCoord.z;
+
+    if (_calibrated) {
+        screenSample.x = tmpCoord.x;
+        screenSample.y = tmpCoord.y;
+
+        getDisplayPoint(&displayPoint, &screenSample, &_calibMatrix);
+
+        coord.x = displayPoint.x;
+        coord.y = displayPoint.y;
+    }
+    else {
+        coord.x = tmpCoord.x;
+        coord.y = tmpCoord.y;
+    }
+
+}
+
+void TSC2046::calibrate(touchCoordinate_t &ref1,
+        touchCoordinate_t &ref2,
+        touchCoordinate_t &ref3,
+        touchCoordinate_t &scr1,
+        touchCoordinate_t &scr2,
+        touchCoordinate_t &scr3) {
+
+    calibPoint_t disp[3];
+    calibPoint_t scr[3];
+
+    disp[0].x = ref1.x;
+    disp[0].y = ref1.y;
+    disp[1].x = ref2.x;
+    disp[1].y = ref2.y;
+    disp[2].x = ref3.x;
+    disp[2].y = ref3.y;
+
+    scr[0].x = scr1.x;
+    scr[0].y = scr1.y;
+    scr[1].x = scr2.x;
+    scr[1].y = scr2.y;
+    scr[2].x = scr3.x;
+    scr[2].y = scr3.y;
+
+    setCalibrationMatrix(disp, scr, &_calibMatrix);
+
+    _calibrated = true;
+
+}
+
+void TSC2046::uncalibrate() {
+    _calibrated = false;
+}
+
+
+void TSC2046::init() {
+
+    _cs = 0;
+
+    _spi.write(REF_ON);
+    _spi.write((READ_12BIT_SER(ADS_A2A1A0_vaux) | ADS_PD10_ALL_ON));
+    _spi.write(PWRDOWN);
+
+    _cs = 1;
+}
+
+void TSC2046::readAndFilter(touchCoordinate_t &coord)
+{
+    int32_t ix, iy, iz1, iz2 = 0;
+    int32_t lastx, lasty, lastz1, lastz2 = 0;
+    int i = 0;
+
+    coord.x = 0;
+    coord.y = 0;
+    coord.z = 0;
+
+    lasty = getFilteredValue(READ_Y(0));
+    lasty >>= 3;
+    if (lasty >= 4095) {
+        lasty = 0;
+    }
+
+    lastx = getFilteredValue(READ_X(0));
+    lastx >>= 3;
+    if (lastx >= 4095) {
+        lastx = 0;
+    }
+
+    lastz1 = getFilteredValue(READ_Z1(0));
+    lastz1 >>= 3;
+
+    lastz2 = getFilteredValue(READ_Z2(0));
+    lastz2 >>= 3;
+
+
+    if (lastx && lastz1) {
+        coord.z = (lastx * ABS(lastz2 - lastz1)) / lastz1;
+    }
+    else {
+        coord.z = 0;
+    }
+
+    if (coord.z > 20000) {
+        coord.z = 0;
+    }
+
+    if (coord.z == 0) {
+        return;
+    }
+
+    for (i = 0; i < DEBOUNCE_MAX; i++) {
+        iy = getFilteredValue(READ_Y(0));
+        iy >>= 3;
+
+        if (ABS (lasty - iy) <= DEBOUNCE_TOL) {
+            break;
+        }
+
+        lasty = iy;
+    }
+
+    for (i = 0; i < DEBOUNCE_MAX; i++) {
+        ix = getFilteredValue(READ_X(0));
+        ix >>= 3;
+        if (ix > 4095) {
+            ix = 0;
+        }
+
+        if (ABS (lastx - ix) <= DEBOUNCE_TOL) {
+            break;
+        }
+
+        lastx = ix;
+    }
+
+    for (i = 0; i < DEBOUNCE_MAX; i++) {
+        iz1 = getFilteredValue(READ_Z1(0));
+        iz1 >>= 3;
+
+        if (ABS (lastz1 - iz1) <= DEBOUNCE_TOL) {
+            break;
+        }
+
+        lastz1 = iz1;
+    }
+
+    for (i = 0; i < DEBOUNCE_MAX; i++) {
+        iz2 = getFilteredValue(READ_Z2(0));
+        iz2 >>= 3;
+
+        if (ABS (lastz2 - iz2) <= DEBOUNCE_TOL) {
+            break;
+        }
+
+        lastz2 = iz2;
+    }
+
+    coord.x = ix;
+    coord.y = iy;
+
+    if (ix && iz1) {
+        coord.z = (ix * ABS(iz2 - iz1)) / iz1;
+    }
+    else {
+        coord.z = 0;
+    }
+
+    if (coord.z > 20000) {
+        coord.z = 0;
+    }
+
+}
+
+int32_t TSC2046::getFilteredValue(int cmd)
+{
+    int32_t a[7];
+    int32_t tmp = 0;
+    int i = 0, j = 0;
+
+    /*
+     * Median and averaging filter
+     *
+     * 1. Get 7 values
+     * 2. Sort these values
+     * 3. Take average of the 3 values in the middle
+     */
+
+    for (i = 0; i < 7; i++) {
+        a[i] = spiTransfer(cmd);
+    }
+
+    // bubble sort
+    for (i = 0; i < 7; i++) {
+        for (j = 0; j < (7-(i+1)); j++) {
+            if (a[j] > a[j+1]) {
+                // swap
+                tmp = a[j];
+                a[j] = a[j+1];
+                a[j+1] = tmp;
+            }
+        }
+    }
+
+    // average of 3 values in the middle
+    return ((a[2]+a[3]+a[4])/3);
+}
+
+uint16_t TSC2046::spiTransfer(uint8_t cmd)
+{
+    uint8_t data[3];
+
+    _cs = 0;
+
+    /*data[0] = */_spi.write(cmd);
+    data[0] = _spi.write(0xff);
+    data[1] = _spi.write(0xff);
+
+    _cs = 1;
+
+    return ((data[0] << 8) | data[1]);
+}
+
+
+// ############################################################################
+// >>>>>>>> Calibrate code >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+// ############################################################################
+
+
+/*
+ *
+ *   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.
+ *
+ *
+ *
+ *   File Name:  calibrate.c
+ *
+ *
+ *   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 utilitities
+ *     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.
+ *
+ *
+ */
+int TSC2046::setCalibrationMatrix( calibPoint_t * displayPtr,
+        calibPoint_t * screenPtr,
+        calibMatrix_t * matrixPtr)
+{
+    int  retValue = 0 ;
+
+
+    matrixPtr->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( matrixPtr->Divider == 0 )
+    {
+        retValue = 1 ;
+    }
+    else
+    {
+        matrixPtr->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)) ;
+        matrixPtr->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)) ;
+        matrixPtr->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 ;
+        matrixPtr->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)) ;
+
+        matrixPtr->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)) ;
+        matrixPtr->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 ;
+    }
+
+    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.
+ *
+ *
+ */
+int TSC2046::getDisplayPoint( calibPoint_t * displayPtr,
+        calibPoint_t * screenPtr,
+        calibMatrix_t * matrixPtr )
+{
+    int  retValue = 0 ;
+
+    if( matrixPtr->Divider != 0 )
+    {
+        /* 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.                                           */
+        displayPtr->x = ( (matrixPtr->An * screenPtr->x) +
+                (matrixPtr->Bn * screenPtr->y) +
+                matrixPtr->Cn
+        ) / matrixPtr->Divider ;
+        displayPtr->y = ( (matrixPtr->Dn * screenPtr->x) +
+                (matrixPtr->En * screenPtr->y) +
+                matrixPtr->Fn
+        ) / matrixPtr->Divider ;
+    }
+    else
+    {
+        retValue = 1 ;
+    }
+    return( retValue ) ;
+}
+
+
+// ############################################################################
+// <<<<<<<< Calibrate code <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+// ############################################################################
+
+
+