gt911_touchscreen.cpp

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#include "gt911_touchscreen.h"
 
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
#include "esphome/core/gpio.h"
 
namespace esphome::gt911 {
 
ESPHOME_LOG_TAG(TAG, "gt911.touchscreen");
 
static const uint8_t PRIMARY_ADDRESS = 0x5D;    // default I2C address for GT911
static const uint8_t SECONDARY_ADDRESS = 0x14;  // secondary I2C address for GT911
static const uint8_t GET_TOUCH_STATE[2] = {0x81, 0x4E};
static const uint8_t CLEAR_TOUCH_STATE[3] = {0x81, 0x4E, 0x00};
static const uint8_t GET_TOUCHES[2] = {0x81, 0x4F};
static const uint8_t GET_SWITCHES[2] = {0x80, 0x4D};
static const uint8_t GET_MAX_VALUES[2] = {0x80, 0x48};
static const size_t MAX_TOUCHES = 5;  // max number of possible touches reported
static const size_t MAX_BUTTONS = 4;  // max number of buttons scanned
 
#define ERROR_CHECK(err) \
  if ((err) != i2c::ERROR_OK) { \
    this->status_set_warning(LOG_STR(ESP_LOG_MSG_COMM_FAIL)); \
    return; \
  }
 
// Reset sequence (Goodix GT911 datasheet): INT held low while RST is released selects address 0x5D, then
// T3 + T4 pass before INT is handed back to the chip as its interrupt output
static constexpr uint32_t RESET_LOW_MS = 10;
static constexpr uint32_t RESET_SETTLE_MS = 5 + 50 + 1;
 
void GT911Touchscreen::setup() {
  if (this->reset_pin_ != nullptr) {
    this->reset_pin_->setup();
    this->reset_pin_->digital_write(false);
    if (this->interrupt_pin_ != nullptr) {
      this->interrupt_pin_->setup();
      this->interrupt_pin_->pin_mode(gpio::FLAG_OUTPUT);
      this->interrupt_pin_->digital_write(false);
    }
    this->set_timeout(RESET_LOW_MS, [this] {
      this->reset_pin_->digital_write(true);
      this->set_timeout(RESET_SETTLE_MS, [this] { this->setup_internal_(); });
    });
    return;
  }
  this->setup_internal_();
}
 
void GT911Touchscreen::setup_internal_() {
  // Expander pins must leave output mode too, or the chip cannot drive its interrupt line
  if (this->interrupt_pin_ != nullptr)
    this->interrupt_pin_->pin_mode(gpio::FLAG_INPUT);
 
  uint8_t data[4];
  i2c::ErrorCode err = this->write(GET_SWITCHES, sizeof(GET_SWITCHES));
  if (err != i2c::ERROR_OK && this->address_ == PRIMARY_ADDRESS) {
    this->address_ = SECONDARY_ADDRESS;
    err = this->write(GET_SWITCHES, sizeof(GET_SWITCHES));
  }
  if (err == i2c::ERROR_OK) {
    err = this->read(data, 1);
    if (err == i2c::ERROR_OK) {
      ESP_LOGD(TAG, "Switches ADDR: 0x%02X DATA: 0x%02X", this->address_, data[0]);
 
      // data[0] & 1 == 1  =>  controller uses falling edge  =>  active-low
      // data[0] & 1 == 0  =>  controller uses rising  edge  =>  active-high
      bool active_high = !(data[0] & 1);
 
      if (this->interrupt_pin_ != nullptr) {
        if (this->interrupt_pin_->is_internal()) {
          // Direct MCU pin: attach a hardware interrupt, no polling needed.
          this->attach_interrupt_(static_cast<InternalGPIOPin *>(this->interrupt_pin_),
                                  active_high ? gpio::INTERRUPT_RISING_EDGE : gpio::INTERRUPT_FALLING_EDGE);
          ESP_LOGD(TAG, "Interrupt pin: hardware interrupt, active %s",
                   active_high ? LOG_STR_LITERAL("HIGH") : LOG_STR_LITERAL("LOW"));
        } else {
          // IO expander pin: no hardware interrupt, the touch state is polled.
          ESP_LOGD(TAG, "Interrupt pin: IO expander polling mode, active %s",
                   active_high ? LOG_STR_LITERAL("HIGH") : LOG_STR_LITERAL("LOW"));
        }
      }
    }
  }
 
  if (this->x_raw_max_ == 0 || this->y_raw_max_ == 0) {
    // no calibration? Attempt to read the max values from the touchscreen.
    if (err == i2c::ERROR_OK) {
      err = this->write(GET_MAX_VALUES, sizeof(GET_MAX_VALUES));
      if (err == i2c::ERROR_OK) {
        err = this->read(data, sizeof(data));
        if (err == i2c::ERROR_OK) {
          this->x_raw_max_ = encode_value_le<uint16_t>(data);
          this->y_raw_max_ = encode_value_le<uint16_t>(&data[2]);
          if (this->swap_x_y_)
            std::swap(this->x_raw_max_, this->y_raw_max_);
        }
      }
    }
    if (err != i2c::ERROR_OK) {
      this->mark_failed(LOG_STR("Calibration error"));
      return;
    }
  }
 
  if (err != i2c::ERROR_OK) {
    this->mark_failed(LOG_STR(ESP_LOG_MSG_COMM_FAIL));
    return;
  }
  this->setup_done_ = true;
}
 
void GT911Touchscreen::update_touches() {
  this->skip_update_ = true;  // skip send touch events by default, set to false after successful error checks
  if (!this->setup_done_) {
    return;
  }
 
  i2c::ErrorCode err;
  uint8_t touch_state = 0;
  uint8_t data[MAX_TOUCHES + 1][8];  // 8 bytes each for each point, plus extra space for the key byte
 
  err = this->write(GET_TOUCH_STATE, sizeof(GET_TOUCH_STATE));
  ERROR_CHECK(err);
  err = this->read(&touch_state, 1);
  ERROR_CHECK(err);
  this->write(CLEAR_TOUCH_STATE, sizeof(CLEAR_TOUCH_STATE));
  uint8_t num_of_touches = touch_state & 0x07;
 
  if ((touch_state & 0x80) == 0 || num_of_touches > MAX_TOUCHES) {
    return;
  }
 
  err = this->write(GET_TOUCHES, sizeof(GET_TOUCHES));
  ERROR_CHECK(err);
  // num_of_touches is guaranteed to be 0..5. Also read the key data
  err = this->read(data[0], sizeof(data[0]) * num_of_touches + 1);
  ERROR_CHECK(err);
 
  this->skip_update_ = false;  // All error checks passed, send touch events
  for (uint8_t i = 0; i != num_of_touches; i++) {
    uint16_t id = data[i][0];
    uint16_t x = encode_uint16(data[i][2], data[i][1]);
    uint16_t y = encode_uint16(data[i][4], data[i][3]);
    this->add_raw_touch_position_(id, x, y);
  }
  auto keys = data[num_of_touches][0] & ((1 << MAX_BUTTONS) - 1);
  if (keys != this->button_state_) {
    this->button_state_ = keys;
    for (size_t i = 0; i != MAX_BUTTONS; i++) {
      for (auto *listener : this->button_listeners_)
        listener->update_button(i, (keys & (1 << i)) != 0);
    }
  }
}
 
void GT911Touchscreen::dump_config() {
  ESP_LOGCONFIG(TAG, "GT911 Touchscreen:");
  LOG_I2C_DEVICE(this);
  LOG_PIN("  Interrupt Pin: ", this->interrupt_pin_);
  LOG_PIN("  Reset Pin: ", this->reset_pin_);
}
 
}  // namespace esphome::gt911