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Diff: TSC2046.cpp
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--- /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 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< +// ############################################################################ + + +