Implementation file for XPT2046 touch screen controller driver. More...

#include "xpt2046.h"
#include "ili9341.h"

Macros
#define	CMD_X_READ 0b10010000

#define	CMD_Y_READ 0b11010000

Functions
static uint8_t	transmit_receive_byte (uint8_t data)
	Transmits and receives a byte via SPI.

static void	manage_cs (uint8_t state)
	Manages the chip select (CS) pin state.

static void	draw_target (uint32_t x, uint32_t y, uint16_t color)
	Draws a target on the screen at the specified coordinates.

uint8_t	XPT2046_ReadIRQPin (void)
	Reads the IRQ pin state of the XPT2046.

void	XPT2046_ReadData (XPT2046Handle_t *handle)
	Reads calibrated touch coordinates from the XPT2046.

void	XPT2046_ReadRawData (uint16_t x, uint16_t y)
	Reads raw touch data from the XPT2046.

void	XPT2046_IRQHandler (XPT2046Handle_t *handle)
	Handles touch interrupt for the XPT2046.

void	XPT2046_Calibrate (XPT2046Handle_t *handle)
	Calibrates the XPT2046 touch controller.

void	XPT2046_SetCalibrationValues (XPT2046Handle_t handle, XPT2046CalibrationValues_t x_calib, XPT2046CalibrationValues_t *y_calib)
	Sets the calibration values for the XPT2046 touch controller.

void	XPT2046_GetCalibrationValues (XPT2046Handle_t handle, XPT2046CalibrationValues_t x_calib, XPT2046CalibrationValues_t *y_calib)
	Gets the calibration values from the XPT2046 touch controller.

void	XPT2046_Test (XPT2046Handle_t *handle)
	Tests the XPT2046 touch controller.

	__attribute__ ((weak))
	Weak callback function for the XPT2046 touch controller.

Variables
SPI_HandleTypeDef *	xpt2046_spi

static const float	XPT2046_VER_COEF = (float)XPT2046_VER_RES / 4096

static const float	XPT2046_HOR_COEF = (float)XPT2046_HOR_RES / 4096

Detailed Description

Implementation file for XPT2046 touch screen controller driver.

This file contains the implementation of the XPT2046 touch screen controller driver. It includes functions for reading touch coordinates, handling interrupts, calibrating the touch screen, and performing basic tests. The calibration procedure is implemented based on Texas Instruments' application note SLYT277 "Calibration in touch-screen systems".

See also: https://www.ti.com/lit/an/slyt277/slyt277.pdf for calibration details.

Macro Definition Documentation

◆ CMD_X_READ

#define CMD_X_READ 0b10010000

Command for reading X position

◆ CMD_Y_READ

#define CMD_Y_READ 0b11010000

Command for reading Y position

Function Documentation

◆ attribute()

__attribute__ ( (weak) )

Weak callback function for the XPT2046 touch controller.

This function is a weakly defined callback that can be overridden by the user. It is called when a touch event is processed.

Parameters

handle Pointer to the XPT2046 handle structure.

◆ draw_target()

static void draw_target	(	uint32_t	x,
		uint32_t	y,
		uint16_t	color )

static

Draws a target on the screen at the specified coordinates.

This function draws a small target at the specified (x, y) coordinates on the screen with the given color.

Parameters

x	X coordinate of the target.
y	Y coordinate of the target.
color	Color of the target.

◆ manage_cs()

static void manage_cs ( uint8_t state )

static

Manages the chip select (CS) pin state.

This function sets the state of the CS pin to either low (active) or high (inactive).

Parameters

state Desired state of the CS pin (GPIO_PIN_RESET or GPIO_PIN_SET).

◆ transmit_receive_byte()

static uint8_t transmit_receive_byte ( uint8_t data )

static

Transmits and receives a byte via SPI.

This function transmits a byte of data via SPI and receives a byte of data in response.

Parameters

data	Byte of data to be transmitted.

Return values

uint8_t Byte of data received in response.

◆ XPT2046_Calibrate()

void XPT2046_Calibrate ( XPT2046Handle_t * handle )

Calibrates the XPT2046 touch controller.

This function performs calibration of the XPT2046 touch controller using three reference points on the screen. The calibration process is based on the method described in the TI application note SLYT277.

Parameters

handle Pointer to the XPT2046 handle structure.

◆ XPT2046_GetCalibrationValues()

void XPT2046_GetCalibrationValues	(	XPT2046Handle_t *	handle,
		XPT2046CalibrationValues_t *	x_calib,
		XPT2046CalibrationValues_t *	y_calib )

Gets the calibration values from the XPT2046 touch controller.

This function retrieves the current calibration values from the XPT2046 touch controller.

Parameters

handle	Pointer to the XPT2046 handle structure.
x_calib	Pointer to store the calibration values for the X axis.
y_calib	Pointer to store the calibration values for the Y axis.

◆ XPT2046_IRQHandler()

void XPT2046_IRQHandler ( XPT2046Handle_t * handle )

Handles touch interrupt for the XPT2046.

This function is the interrupt handler for the XPT2046 touch controller. It reads the touch data and updates the touch state.

Parameters

handle Pointer to the XPT2046 handle structure.

◆ XPT2046_ReadData()

void XPT2046_ReadData ( XPT2046Handle_t * handle )

Reads calibrated touch coordinates from the XPT2046.

This function reads raw touch data from the XPT2046 and applies calibration coefficients to convert them to screen coordinates.

Parameters

handle Pointer to the XPT2046 handle structure.

◆ XPT2046_ReadIRQPin()

uint8_t XPT2046_ReadIRQPin ( void )

Reads the IRQ pin state of the XPT2046.

This function reads the state of the IRQ pin of the XPT2046 touch controller.

Return values

uint8_t 1 if the pin is high, 0 if the pin is low.

◆ XPT2046_ReadRawData()

void XPT2046_ReadRawData	(	uint16_t *	x,
		uint16_t *	y )

Reads raw touch data from the XPT2046.

This function reads the raw touch data from the XPT2046 touch controller by sending appropriate commands via SPI and processing the received data. It implements a simple averaging filter to improve the touch data quality.

Parameters

x	Pointer to store the raw x-coordinate.
y	Pointer to store the raw y-coordinate.

◆ XPT2046_SetCalibrationValues()

void XPT2046_SetCalibrationValues	(	XPT2046Handle_t *	handle,
		XPT2046CalibrationValues_t *	x_calib,
		XPT2046CalibrationValues_t *	y_calib )

Sets the calibration values for the XPT2046 touch controller.

This function updates the calibration values for the XPT2046 touch controller.

Parameters

handle	Pointer to the XPT2046 handle structure.
x_calib	Pointer to the calibration values for the X axis.
y_calib	Pointer to the calibration values for the Y axis.

◆ XPT2046_Test()

void XPT2046_Test ( XPT2046Handle_t * handle )

Tests the XPT2046 touch controller.

This function tests the XPT2046 touch controller by reading the touch coordinates and drawing a target on the screen at the touch location.

Parameters

handle Pointer to the XPT2046 handle structure.

Variable Documentation

◆ xpt2046_spi

SPI_HandleTypeDef* xpt2046_spi

extern

SPI handle for the XPT2046 touch screen

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ CMD_X_READ

◆ CMD_Y_READ

Function Documentation

◆ __attribute__()

◆ draw_target()

◆ manage_cs()

◆ transmit_receive_byte()

◆ XPT2046_Calibrate()

◆ XPT2046_GetCalibrationValues()

◆ XPT2046_IRQHandler()

◆ XPT2046_ReadData()

◆ XPT2046_ReadIRQPin()

◆ XPT2046_ReadRawData()

◆ XPT2046_SetCalibrationValues()

◆ XPT2046_Test()

Variable Documentation

◆ xpt2046_spi

◆ attribute()