XPT2046 MODULE

This module contains C library for resistive touch embedded on 3.5" SPI TFT 480x320 display. Used touch controler is XPT2046. Module was written and tested on STM32F746 Nucleo board, using STM32CubeIDE.

Dependencies

XPT2046 used also diplay ILI9488 module for calibration purposes. Display module can be found under this link.

Definition of float32_t must be provided by user. In current implementation it is defined in "project_config.h". Just add following statement to your code where it suits the best.

// Define float
typedef float float32_t;

Usage

1. Setting up configuration

Display driver is fully configurable via xpt2046_cfg.h file. Low level interface shall be change only in xpt2046_if.c/.h files.

NOTE: When debug mode is enabled user should provide debug communication port by the choice!

2. Low level interface

• User shall change xpt2046_if.c/.h file between USER_CODE_BEGIN and USER_CODE_END sections. Template files with examples can be found in /template subdirectory.

3. Includes

Only top level modules are needed, therefore single include should be provided. E.g.:

  #include "xpt2046.h"

4. Initialization

• Initialization of tocuh driver should be done only once in project.
• User can access initilization status by calling xpt2046_is_init() function.
• Example of initialization routine:

  // Init touch controller
  if ( eXPT2046_OK != xpt2046_init() )
  { 
    // Initialization failed, further actions here...
  }

5. Handle touch

• Touch controler (xpt2046) need to be handled every x ms in order to preserve real-time behaviour. Thus calling xpt2046_hndl() every x ms is mandatory.
• Example of touch handling invocation:

  // Touch task or simple main loop
  @every x ms
  {
    // Handle touch controller
    xpt2046_hndl();
  }

• Access touch data via xpt2046_get_touch() function. This function only returns values from local data and doesn't interface with touch controler itself.
• Example of reading touch data:

  // Touch variables
  uint16_t x_pos;
  uint16_t y_pos;
  uint16_t force;
  bool touch;
  
  // Get touch data
  xpt2046_get_touch( &x_pos, &y_pos, &force, &touch );

  // Add here furher actions based on touch data...

Touch API

• xpt2046_status_t xpt2046_init (void);

• bool xpt2046_is_init (void);

• void xpt2046_hndl (void);

• xpt2046_status_t xpt2046_get_touch (uint16_t * const p_page, uint16_t * const p_col, uint16_t * const p_force, bool * const p_pressed);

• xpt2046_status_t xpt2046_start_calibration (void);

• bool xpt2046_is_calibrated (void);

• void xpt2046_set_cal_factors (const int32_t * const p_factors);

• void xpt2046_get_cal_factors (const int32_t * p_factors);