The I2C Interface

Capacitive touch screens usually use the I2C (Inter-Integrated Circuit) interface to communicate with the motherboard.  

 

The I2C interface provides a convenient and relatively simple way for capacitive screens to enable bi-directional communication between the touch screen and the motherboard through two lines (SDA and SCL).

 

This connection can be made directly on the FPC. I2CC is a bit more required  and needs some programming and writing I2C support code to use the device with the controller.

 

The USB Interface

USB (Universal Serial Bus) is a universal and widely supported interface standard that can achieve fast and stable data transmission between various devices.

 

This design of this interface enables the capacitive touch screen to be connected to computers, tablets, smartphones and other devices via USB to achieve touch input and data interaction with the motherboard.

 

The main advantage of USB is the plug-and-play. Operating systems such as Windows and Linux will be equipped with relevant USB drivers to operate the device. There is a choice of ZIF (direct to FPC) or USB 4-pin connection.

 

How to Choose the I2C or USB Interface?

Choose I2C Interface

 

Simplify Connection

 

If you want the system connection to be simpler, the I2C interface only requires two wires (SDA and SCL). Compared with the USB interface, the connection is simpler.

 

Low Power Consumption

 

The I2C communication protocol usually has lower power consumption and may be more suitable for some devices with higher power consumption requirements.

 

Suitable for Embedded Systems

 

The I2C interface is suitable for embedded systems and can provide more flexible solutions for some small electronic devices and embedded applications.

 

Multi-device Connection

 

The I2C bus supports multiple device connections, so multiple I2C devices can be easily integrated into the same system.

 

Low Cost Design

 

If system cost is a constraint, the I2C interface is usually a lower-cost option.

 

Choose USB Interface

 

High Speed of Data Transfer

 

If the application requires a higher data transfer rate, especially for images, videos and other large data volume applications, the USB interface may be more suitable, especially USB 3.0 and above.

 

Broad Compatibility

 

USB is a universal interface standard that is supported by almost all computers and many other devices. If your device needs to connect to multiple devices, USB provides wider compatibility.

 

Power Supply

 

The USB interface can provide power supply, which is an advantage for some devices and can simplify power management.

 

Complex Human-machine Interface

 

Applications need to support complex human-machine interfaces, such as multi-touch, gesture recognition and other functions. USB interface is usually more suitable.

 

Desktop or Laptop Applications

 

The USB interface is more suitable for connecting to personal computer devices such as desktop computers and laptops.

 

Features/parameters	USB Interface	I2C Interface
Data transfer rate	High, especially USB 3.0 and above	Relatively low, depending on the specific I2C rate
Power supply	Provide power supply	Normally no power supply provided, additional power cord required
Connection complexity	Relatively complex, requiring multiple pins and cables	Simplified connections, only two wires (SDA and SCL)
Compatibility	Widely compatible, almost all devices support USB	Suitable for embedded systems, more flexible devices that need to support I2C
Power consumption	Usually higher	Usually lower
Human-machine interface support	Suitable for complex human-machine interface, multi-touch, etc.	Suitable for some basic touch interactions
Multi-device connection	Requires additional equipment to support USB hub, etc.	I2C bus supports multiple device connections
Cost	Usually higher	Usually lower
Application	Desktop computers, laptops, etc.	Embedded systems, small electronic devices, etc.

Table 1. Comparison of I2C and USB interfaces