ILI9341 TFTLCD Touch Screen driver

The lcd-touch library should work with any STM32 board that has a compartment (slot) for TFT LCD shield*. The rest of the project provides an example of how to use the lcd-touch lib on Nucleo F446RE. If your driver is different from ILI9341, refer to lcd.h.

*TFT Shield: 2.4 Inch TFT LCD Shield ILI9341 HX8347 240x320 Touch Board 65K RGB (~$7).

The interface is not SPI: instead, the communication with the LCD is done by acting directly on GPIO Pins and therefore is faster than an SPI alternative implementation, which you could probably find somewhere else.

LCD Touch pinout

• Y- PB10
• Y+ PA4, EXTI4
• X- PA1
• X+ PA8

In idle state, PA4 is in interrupt mode awaiting for touches. You can't draw and await for touches simultaneously.

Measuring X-pos

• set PA1 to logical 0
• set PA8 to logical 1
• set PB10 in input mode
• set PA4 in analog mode
• get value from ADC2 channel 4

Measuring Y-pos

• disable EXTI4 line
• set PB10 to logical 0
• set PA4 to logical 1
• set PA8 in input mode
• set PA1 in analog mode
• get value from ADC1 channel 1
• clear EXTI4 line pending interrupt
• enable EXTI4 line

How to use

// initialize ADC1 & ADC2

LCD_Init();
LCD_Touch_Init(&hadc2, ADC_CHANNEL_4, &hadc1, ADC_CHANNEL_1);
LCD_SetMode(LCD_MODE_TOUCH);
LCD_TouchPoint p;

while (1) {
    if (LCD_Touch_Read(&p) == LCD_TOUCH_READ_SUCCESS) {
        // draw the last stroke, for example
        LCD_Touch_Draw_ConnectLastPoint(&p);

        // do whatever you want with the touch point `p`
        ...
    }
}

LCD_TouchPoint is a struct that holds X and Y position, time, and touch state that can be one of LCD_TOUCH_DOWN, LCD_TOUCH_MOVE, or LCD_TOUCH_UP.

Note. Optimization flags other than None are unstable at the moment.

Notes on IDE

The project was originally written in SystemWorkbench, then converted to TrueAtollicStudio to become eventually suppressed by STMCubeIDE.

OS: Ubuntu 18.04

If you're unable to open/convert the project in one of the listed above IDEs, open an issue.

Demo on YouTube