3.2 inch touch screen TFT LCD color screen module ILI9341 compatible with atomic 34P LCD interface 240*320 34Pin

Pinout & Interface Guide

These 34-pin modules follow a relatively standardized pinout specific to the “atomic” 34P interface.

Power & Backlight

• 1 (5V): 5V input (use with 3.3V regulator on board)

• 2 (GND): Power Ground

• 25 (BLVCC): Backlight Power (5V or 3.3V)

• 26 (BLGND): Backlight Ground

• 27 (BLCNT): Backlight Brightness Control (PWM Input)

LCD Control (Direct Connect to MCU)

• 19 (CS): LCD Chip Select (Active Low)

• 20 (RS/DC): Data/Command Select pin

• 21 (WR): Write strobe signal

• 22 (RD): Read strobe signal

• 23 (RESET): LCD Hardware Reset

Data Bus

• 3 – 18 (DB0 – DB15): 8/16-bit bidirectional data bus.

MicroSD Card (SPI Interface)

• 29 (TP_CS / SD_CS): Card Select (Check your board: sometimes shared with Touch or separate)

• 30 (SCK): SPI Clock

• 31 (MOSI): Master Out Slave In

• 32 (MISO): Master In Slave Out

Touchscreen (XPT2046 – SPI Interface)

• 28 (TP_IRQ): Touch Interrupt (detects screen press)

• 29 (TP_CS): Touch Chip Select

• 30 (TP_SCK): SPI Clock (Shared with SD Card)

• 31 (TP_SI): SPI MOSI (Shared with SD Card)

• 32 (TP_SO): SPI MISO (Shared with SD Card)

• 34 (GND): Ground

Note: Pins may vary slightly between manufacturers. Always verify the silkscreen on your specific board.

Usage Guide

1. Hardware Setup

This module uses a 16-bit parallel interface for the display, which requires more GPIO pins than SPI, but offers significantly faster refresh rates.

1. Connect Power: Connect the 5V and GND pins to your MCU’s 5V and GND.

2. Connect Data Pins: Connect the 16 data pins (DB0-DB15) to available digital I/O pins on your MCU.

3. Connect Control Pins: Connect CS, RS, WR, RD, and RST to additional digital pins.

4. Touch/SD Card: Connect the SPI pins (SCK, MOSI, MISO) to your primary hardware SPI bus. Use unique Chip Select (CS) pins for the Touch and SD Card.

2. Software Setup (STM32 / Arduino IDE)

The ILI9341 is supported by several powerful open-source libraries.

Using the MCUfriend Library (Highly Recommended)

The “MCUfriend” library (often UTFT or UTFTGHL) is specifically designed for these high-pin count TFTs.

1. Download and install the UTFT (or UTFTGHL) library in your Arduino IDE.

2. Look for the hardware profile for “CTE32” or “ITDB32S” (CTE32 is the standard identifier for the 3.2-inch 16-bit module).

3. Pin Assignment: The constructor usually follows the order: (RS, WR, CS, RST, [Optional]).

// Example using UTFT library (CTE32 Profile)
#include <UTFT.h>
// TFT01: RS, WR, CS, RST
UTFT myGLCD(CTE32, 19, 21, 20, 22); // Adjust pins based on your wiring

Using LVGL (High Performance)

For complex user interfaces, LVGL (Light and Versatile Graphics Library) supports the ILI9341 via its MIPI driver interface. You’ll need to implement the send_cmd and send_color callbacks for your hardware .

3. Calibrating Touch (XPT2046)

The resistive touch panel requires calibration:

1. Install the XPT2046_Touchscreen library.

2. Run the calibration sketch provided by the library.

3. The sketch will ask you to touch the corners of the screen.

4. Note the raw ADC (Analog-to-Digital Converter) values and use them in your main project to map the touch coordinates to the 240×320 screen resolution.

4. Troubleshooting SPI Conflicts (Touch + SD Card)

A common issue occurs when the SD card and Touch controller share the same SPI bus but their libraries are not properly managed. If one works and the other doesn’t, specifically check that you are using Hardware SPI for both and that you are correctly setting the Chip Select (CS) pins high/low when switching between the two devices .