touch.cpp

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#include "touch.h"
#include "HSI.h"
#include "Eris.h"
 
#define Z_THRESHOLD     600
#define Z_THRESHOLD_INT 75
#define MSEC_THRESHOLD  50
#define SPI_SETTING     SPISettings(2000000, MSBFIRST, SPI_MODE0)
 
bool Touch::begin(){
    Serial.println("Touch:begin");
    SPI1.setMISO(SDI);
    SPI1.setMOSI(SDO);
    SPI1.setSCK(SCLK);
    SPI1.begin();
    pinMode(csPin, OUTPUT);
    digitalWrite(csPin, HIGH);
    tirqPin = 255; //255 = not used
    return true;
}
 
static int16_t besttwoavg( int16_t x , int16_t y , int16_t z ) {
  int16_t da, db, dc;
  int16_t reta = 0;
  if ( x > y ) da = x - y; else da = y - x;
  if ( x > z ) db = x - z; else db = z - x;
  if ( z > y ) dc = z - y; else dc = y - z;
  if ( da <= db && da <= dc ) reta = (x + y) >> 1;
  else if ( db <= da && db <= dc ) reta = (x + z) >> 1;
  else reta = (y + z) >> 1;   //    else if ( dc <= da && dc <= db ) reta = (x + y) >> 1;
  return (reta);
}
 
void FLASHMEM Touch::update()
{
    //Serial.println("Touch:update");
    int16_t data[6];
 
    if (!isrWake) return;
    uint32_t now = millis();
    if (now - msraw < MSEC_THRESHOLD) return;
 
    SPI1.beginTransaction(SPI_SETTING);
    digitalWrite(csPin, LOW);
    SPI1.transfer(0xB1 /* Z1 */);
    int16_t z1 = SPI1.transfer16(0xC1 /* Z2 */) >> 3;
    int z = z1 + 4095;
    int16_t z2 = SPI1.transfer16(0x91 /* X */) >> 3;
    z -= z2;
    if (z >= Z_THRESHOLD) {
        SPI1.transfer16(0x91 /* X */);  // dummy X measure, 1st is always noisy
        data[0] = SPI1.transfer16(0xD1 /* Y */) >> 3;
        data[1] = SPI1.transfer16(0x91 /* X */) >> 3; // make 3 x-y measurements
        data[2] = SPI1.transfer16(0xD1 /* Y */) >> 3;
        data[3] = SPI1.transfer16(0x91 /* X */) >> 3;
    }
    else data[0] = data[1] = data[2] = data[3] = 0; // Compiler warns these values may be used unset on early exit.
    data[4] = SPI1.transfer16(0xD0 /* Y */) >> 3;   // Last Y touch power down
    data[5] = SPI1.transfer16(0) >> 3;
    digitalWrite(csPin, HIGH);
    SPI1.endTransaction();
    //Serial.printf("z=%d  ::  z1=%d,  z2=%d  ", z, z1, z2);
    if (z < 0) z = 0;
    if (z < Z_THRESHOLD) { //   if ( !touched ) {
        // Serial.println();
        zraw = 0;
        if (z < Z_THRESHOLD_INT) { //   if ( !touched ) {
            if (255 != tirqPin) isrWake = false;
        }
        return;
    }
    zraw = z;
 
    // Average pair with least distance between each measured x then y
    //Serial.printf("    z1=%d,z2=%d  ", z1, z2);
    //Serial.printf("p=%d,  %d,%d  %d,%d  %d,%d", zraw,
        //data[0], data[1], data[2], data[3], data[4], data[5]);
    int16_t x = besttwoavg( data[0], data[2], data[4] );
    int16_t y = besttwoavg( data[1], data[3], data[5] );
 
    //Serial.printf("    %d,%d", x, y);
    //Serial.println();
    if (z >= Z_THRESHOLD) {
        msraw = now;    // good read completed, set wait
        switch (rotation) {
          case 0:
            xraw = 4095 - y;
            yraw = x;
            break;
          case 1:
            xraw = x;
            yraw = y;
            break;
          case 2:
            xraw = y;
            yraw = 4095 - x;
            break;
          default: // 3
            xraw = 4095 - x;
            yraw = 4095 - y;
        }
    }
}
 
bool Touch::touched()
{
    //Serial.println("Touch:touched");
    return (zraw >= Z_THRESHOLD);
}
 
TS_Point Touch::getPoint()
{
    float fx,fy;
    int16_t x,y;
    //Serial.println("Touch:getPoint");
    //update();
    
    //dynamic calibration is supported by monitoring the raw touch limits
    //which are used for the screen space translation calculations      
    if (xraw < _raw_minx) _raw_minx = xraw;
    if (xraw > _raw_maxx) _raw_maxx = xraw;
    if (yraw < _raw_miny) _raw_miny = yraw;
    if (yraw > _raw_maxy) _raw_maxy = yraw;
 
    //normalize the raw touch readings to percentage of full scale (0 to 1)
    fx = (xraw - _raw_minx)/(1.0 * (_raw_maxx - _raw_minx));
    fy = (yraw - _raw_miny)/(1.0 * (_raw_maxy - _raw_miny));
    //convert normalized values to screen space
    x = (int16_t)(fx * SCREEN_WIDTH); 
    y = (int16_t)(fy * SCREEN_HEIGHT);
    (x < 0)?x=0:x=x;
    (y < 0)?y=0:y=y;    
    return TS_Point(SCREEN_WIDTH-x, SCREEN_HEIGHT-y, zraw);
}