marlin/Marlin/src/HAL/STM32F1/tft/xpt2046.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (c) 2019 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

#include "../../../inc/MarlinConfig.h"

#if HAS_TFT_XPT2046

#include "xpt2046.h"
#include <SPI.h>

uint16_t delta(uint16_t a, uint16_t b) { return a > b ? a - b : b - a; }

#if ENABLED(TOUCH_BUTTONS_HW_SPI)
  #include <SPI.h>

  SPIClass XPT2046::SPIx(TOUCH_BUTTONS_HW_SPI_DEVICE);

  static void touch_spi_init(uint8_t spiRate) {
    /**
     * STM32F1 APB2 = 72MHz, APB1 = 36MHz, max SPI speed of this MCU if 18Mhz
     * STM32F1 has 3 SPI ports, SPI1 in APB2, SPI2/SPI3 in APB1
     * so the minimum prescale of SPI1 is DIV4, SPI2/SPI3 is DIV2
     */
    uint8_t clock;
    switch (spiRate) {
      case SPI_FULL_SPEED:    clock = SPI_CLOCK_DIV4;  break;
      case SPI_HALF_SPEED:    clock = SPI_CLOCK_DIV4; break;
      case SPI_QUARTER_SPEED: clock = SPI_CLOCK_DIV8; break;
      case SPI_EIGHTH_SPEED:  clock = SPI_CLOCK_DIV16; break;
      case SPI_SPEED_5:       clock = SPI_CLOCK_DIV32; break;
      case SPI_SPEED_6:       clock = SPI_CLOCK_DIV64; break;
      default:                clock = SPI_CLOCK_DIV2;        // Default from the SPI library
    }
    XPT2046::SPIx.setModule(TOUCH_BUTTONS_HW_SPI_DEVICE);
    XPT2046::SPIx.setClockDivider(clock);
    XPT2046::SPIx.setBitOrder(MSBFIRST);
    XPT2046::SPIx.setDataMode(SPI_MODE0);
  }
#endif // TOUCH_BUTTONS_HW_SPI

void XPT2046::Init() {
  SET_INPUT(TOUCH_MISO_PIN);
  SET_OUTPUT(TOUCH_MOSI_PIN);
  SET_OUTPUT(TOUCH_SCK_PIN);
  OUT_WRITE(TOUCH_CS_PIN, HIGH);

  #if PIN_EXISTS(TOUCH_INT)
    // Optional Pendrive interrupt pin
    SET_INPUT(TOUCH_INT_PIN);
  #endif

  TERN_(TOUCH_BUTTONS_HW_SPI, touch_spi_init(SPI_SPEED_6));

  // Read once to enable pendrive status pin
  getRawData(XPT2046_X);
}

bool XPT2046::isTouched() {
  return isBusy() ? false : (
    #if PIN_EXISTS(TOUCH_INT)
      READ(TOUCH_INT_PIN) != HIGH
    #else
      getRawData(XPT2046_Z1) >= XPT2046_Z1_THRESHOLD
    #endif
  );
}

bool XPT2046::getRawPoint(int16_t *x, int16_t *y) {
  if (isBusy()) return false;
  if (!isTouched()) return false;
  *x = getRawData(XPT2046_X);
  *y = getRawData(XPT2046_Y);
  return isTouched();
}

uint16_t XPT2046::getRawData(const XPTCoordinate coordinate) {
  uint16_t data[3];

  DataTransferBegin();
  TERN_(TOUCH_BUTTONS_HW_SPI, SPIx.begin());

  for (uint16_t i = 0; i < 3 ; i++) {
    IO(coordinate);
    data[i] = (IO() << 4) | (IO() >> 4);
  }

  TERN_(TOUCH_BUTTONS_HW_SPI, SPIx.end());
  DataTransferEnd();

  uint16_t delta01 = delta(data[0], data[1]),
           delta02 = delta(data[0], data[2]),
           delta12 = delta(data[1], data[2]);

  if (delta01 > delta02 || delta01 > delta12)
    data[delta02 > delta12 ? 0 : 1] = data[2];

  return (data[0] + data[1]) >> 1;
}

uint16_t XPT2046::IO(uint16_t data) {
  return TERN(TOUCH_BUTTONS_HW_SPI, HardwareIO, SoftwareIO)(data);
}

#if ENABLED(TOUCH_BUTTONS_HW_SPI)
  uint16_t XPT2046::HardwareIO(uint16_t data) {
    uint16_t result = SPIx.transfer(data);
    return result;
  }
#endif

uint16_t XPT2046::SoftwareIO(uint16_t data) {
  uint16_t result = 0;

  for (uint8_t j = 0x80; j; j >>= 1) {
    WRITE(TOUCH_SCK_PIN, LOW);
    WRITE(TOUCH_MOSI_PIN, data & j ? HIGH : LOW);
    if (READ(TOUCH_MISO_PIN)) result |= j;
    WRITE(TOUCH_SCK_PIN, HIGH);
  }
  WRITE(TOUCH_SCK_PIN, LOW);

  return result;
}

#endif // HAS_TFT_XPT2046