Bluetooth is an open wireless technology standard for exchanging data over short distances using short wavelength radio transmissions from fixed and mobile devices using a packet-based protocol. The wiring method of Bluetooth data transmission is likely to use a serial interface.

What is the serial interface?

It is the serial port that we often say that the data is transmitted in a sequence of one or more bits on a limited number of IOs. There are many such types, generally including: UART, IIC, SPI, CAN, USB, etc., as long as it is a serial transmission interface, it is a kind of serial port. It is worth mentioning here that since people used to call the UART port serial port in the early days, everyone usually refers to the UART interface when referring to the serial port.

The difference between UART, SPI, and IIC

UART interface

UART (Universal Asynchronous Receiver/Transmitter) serial interface is the most commonly used communication technology for single-chip microcomputers. It is usually used for communication between single-chip microcomputer and computer and between single-chip microcomputer and single-chip microcomputer.

SPI interface

SPI (Serial Peripheral Interface) is the serial peripheral interface. SPI is a synchronous serial data transmission standard and a high-speed, full-duplex, synchronous communication bus that is widely used in many devices.

IIC interface

IIC (Inter-Integrated Circuit), also known as I2C, is a two-wire serial bus structure for connecting a microcontroller and its peripherals. The main advantages of the IIC bus are simplicity and effectiveness.

The difference 1
UART is two lines, one sends a receiver, can be full-duplex communication, the number of lines is also relatively small. The data is transmitted asynchronously, and the timing requirements for both parties are strict, and the communication speed is not very fast. Most used in multi-machine communication.

The difference 2.
SPI interface and the above UART, there is a synchronous clock line, the shortcoming of the above UART is its advantages, the timing requirements of the two sides of the communication are not strictly different devices can be easily combined, and the communication speed is very fast. Generally used in high-speed data communication between internal components of products, such as large-capacity memory.

Difference 3
IIC interface is also a two-wire interface, it is the transmission of data between the two lines through a complex logical relationship, the communication speed is not high, the program is also more complicated to write. The general single-chip system is mainly used to connect with 24C02 and other small easy memory.

Note: SPI and UART can achieve full duplex, but I2C does not work; I2C is slower than SPI, the protocol is a bit more complicated than SPI, but the connection is less than the standard SPI.

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