InfiniTime/src/drivers/Cst816s.cpp

#include <FreeRTOS.h>
#include <task.h>
#include <nrfx_log.h>
#include <legacy/nrf_drv_gpiote.h>

#include "Cst816s.h"
using namespace Pinetime::Drivers;

/* References :
 * This implementation is based on this article : https://medium.com/@ly.lee/building-a-rust-driver-for-pinetimes-touch-controller-cbc1a5d5d3e9
 * Touch panel datasheet (weird chinese translation) : https://wiki.pine64.org/images/5/51/CST816S%E6%95%B0%E6%8D%AE%E6%89%8B%E5%86%8CV1.1.en.pdf
 *
 * TODO : we need a complete datasheet and protocol reference!
 * */

void Pinetime::Drivers::Cst816S::Init() {
  nrf_gpio_cfg_output(pinReset);
  nrf_gpio_pin_clear(pinReset);
  vTaskDelay(20);
  nrf_gpio_pin_set(pinReset);
  vTaskDelay(200);

  nrfx_twi_config_t config;
  config.frequency = NRF_TWI_FREQ_400K;
  config.scl = 7;
  config.sda = 6;
  config.interrupt_priority = NRFX_TWI_DEFAULT_CONFIG_IRQ_PRIORITY;
  config.hold_bus_uninit = NRFX_TWI_DEFAULT_CONFIG_HOLD_BUS_UNINIT;

  // Configure TWI in blocking mode (event_handler = nullptr)
  auto ret = nrfx_twi_init(&twi, &config, nullptr, this);
  nrfx_twi_enable(&twi);
}


void Cst816S::Probe() {
  nrfx_err_t ret;
  for(int i = 0; i < 127; i++) {
    uint8_t data;
    ret = nrfx_twi_rx(&twi, i, &data, 1);
    if(ret == NRFX_SUCCESS) {
      NRF_LOG_INFO("I2C device detected at address %d", i);
    }
  }
}

Cst816S::TouchInfos Cst816S::GetTouchInfo() {
  Cst816S::TouchInfos info;

  nrfx_twi_rx(&twi, address, touchData, 63);
  auto nbTouchPoints = touchData[2] & 0x0f;

  uint8_t i = 0;
  uint8_t pointId = (touchData[touchIdIndex + (touchStep * i)]) >> 4;
  if(nbTouchPoints == 0 && pointId == lastTouchId) return info;

  // We fetch only the first touch point (the controller seems to handle only one anyway...)
  info.isTouch = true;

  auto xHigh = touchData[touchXHighIndex + (touchStep * i)] & 0x0f;
  auto xLow = touchData[touchXLowIndex + (touchStep * i)];
  uint16_t x = (xHigh << 8) | xLow;

  auto yHigh = touchData[touchYHighIndex + (touchStep * i)] & 0x0f;
  auto yLow = touchData[touchYLowIndex + (touchStep * i)];
  uint16_t y = (yHigh << 8) | yLow;

  auto action = touchData[touchEventIndex + (touchStep * i)] >> 6; /* 0 = Down, 1 = Up, 2 = contact*/
  auto finger = touchData[touchIdIndex + (touchStep * i)] >> 4;
  auto pressure = touchData[touchXYIndex + (touchStep * i)];
  auto area = touchData[touchMiscIndex + (touchStep * i)] >> 4;

  info.x = x;
  info.y = y;
  info.action = action;
  return info;
}

void Cst816S::Sleep() {
  nrfx_twi_disable(&twi);
  nrf_gpio_cfg_default(6);
  nrf_gpio_cfg_default(7);
}

void Cst816S::Wakeup() {
  Init();
}