The interface definition for capacitive touchscreens typically depends on their type (e.g., I²C, SPI, USB, etc.) and the manufacturer's design. Below are typical definitions and descriptions for several common interfaces:
1. I²C Interface (commonly used in small-sized touchscreens)
Pin Definitions:
VCC: Power supply positive terminal (typically 3.3V or 5V).
GND: Power supply ground.
SCL: I²C clock line.
SDA: I²C data line.
INT (optional): Interrupt pin, used to trigger touch event notifications.
RST (optional): Reset pin, used for hardware reset of the touch controller.
Features:
Simple and low-cost, suitable for embedded devices (such as Raspberry Pi, STM32, etc.).
Requires configuration of the I²C address (typically via the manual or jumper settings).
2. SPI interface (high refresh rate or large screen applications)
Pin definitions:
VCC/GND: Power supply and ground.
SCK: SPI clock line.
MOSI: Master output, slave input.
MISO: Master input, slave output.
CS/SS: Chip select signal (active low).
IRQ (optional): Interrupt pin.
RST: Reset pin.
Features:
Faster than I²C, suitable for scenarios requiring rapid response.
May require a dedicated SPI controller driver.
3. USB interface (universal touchscreen, plug-and-play)
Pin definitions:
VBUS: USB power supply (5V).
D+: USB data line positive.
D-: USB data line negative.
GND: Power ground.
(Some touchscreens may additionally provide ID or shielding pins)
Features:
Directly compatible with hosts (such as PCs, Android devices) without requiring additional drivers.
Typically supports the HID protocol (Human Interface Device).
4. Other dedicated interfaces
UART (serial port):
Some touchscreens use TX/RX communication and require a custom protocol.
Parallel:
Older devices may use multiple data lines for parallel transmission (e.g., TP_XY1, TP_XY2, etc.).
Notes:
Supply voltage: Confirm whether VCC is 3.3V or 5V to avoid damaging the touch IC.
Pull-up resistor: I²C interfaces typically require an external 4.7kΩ pull-up resistor (some modules have it built-in).
Data Format: Touch coordinates may be raw data or calibrated screen coordinates.
Reference Manual: Pin definitions may vary slightly among different manufacturers (e.g., GT911, FT5x06, CY8C, etc.). Be sure to consult the corresponding data manual.
Feel free to consult WIWO's professional team for touchscreen interface definitions and to select the appropriate touchscreen for your device.