There are many types of capacitive touch screen interfaces, each of which has its own unique characteristics and applicable scenarios. When choosing an interface, it is necessary to consider factors such as communication speed, cost, setup difficulty, power consumption, etc. according to specific application requirements and scenarios. With the continuous development of technology, capacitive touch screen interface is also constantly innovating and improving, in order to adapt to more diverse application needs. Common capacitive touch screen interfaces mainly include the following:
1. I2C (Inter-Integrated Circuit) Interface
Definition: I2C interface is a serial communication protocol, using a two-wire system (SDA data line, SCL clock line), you can simultaneously transmit data and clock.
Features: Since the interface is directly on top of the component, the IIC bus takes up very little space, reducing board space and the number of chip pins, and lowering interconnect costs. The bus can be up to 25 feet long and can support up to 40 components at a maximum transfer rate of 10Kbps. It also supports multiple masters, where any device capable of transmitting and receiving can become a master bus. A master can control the transmission of signals and the clock frequency. Of course, there can only be one master at any point in time.
The capacitive touch screen module communicates with the master board through the I2C interface and transmits data through the I2C bus. It occupies less resources and is simple to implement, but the communication speed is relatively slow.
2. SPI (Serial Peripheral Interface) interface
Definition: SPI interface is a serial communication interface, using a 4-wire system (clock line, data input line, data output line, chip select line).
Features: can issue and receive serial data at the same time, can work as a host or slave, provide frequency programmable clock, found the end of the interrupt flag; bus contention protection, etc..
Capacitive touch screen module through the SPI interface to communicate with the main control board, data transfer speed is slow, generally not recommended.
3. USB (Universal Serial Bus) interface
Definition: USB interface is a commonly used communication interface designed to connect computers and other devices.
Characteristics: In capacitive touch screen module applications, the USB interface can be connected through the OTG (On-The-Go) technology to achieve the capacitive touch screen module as a ‘slave’ access to the main control board.
Provides a high-speed data transmission channel to ensure smooth operation and response speed. Supports plug-and-play functionality, simplifying the installation process.
However, compared with the I2C interface, the USB interface may be more difficult to set up and troubleshoot in some cases, and may cost more and consume more power.
4. UART (Universal Asynchronous Receiver/Transmitter) Interface
Definition: The UART interface is an asynchronous serial communications protocol.
Characteristics: Suitable for low-speed transmission and long-distance communication.
Capacitive touch screen module communicates with the main control board through UART interface, which is slower than I2C and SPI interface, but has the function of long-distance communication.
5. GPIO (General Purpose Input/Output) interface
Definition: GPIO interface is a general purpose input/output interface, which can be flexibly configured with different functions.
Characteristics: In capacitive touch screen module applications, GPIO interface is usually used to control the capacitive touch screen reset, interrupt and other functions.
It is not directly used for data transmission, but plays an important role in the overall control of the touch screen system.