Bluetooth module interfaces

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If you are a hardware engineer who wants to play with Bluetooth, and you don't know the various interfaces on the Bluetooth module, then you are not a qualified hardware engineer. Do you have a thorough understanding of the communication interface on the Bluetooth module? Many people will be dizzy when they hear UART interface, IIC interface, SPI interface, etc., so today we will briefly outline some common interfaces and their differences.

In fact, there are generally two ways to connect data: one is a parallel interface and the other is a serial interface.

What is a parallel interface? It is what we usually call a parallel port, which is an interface that transmits data in parallel. The so-called "parallel" means that data is transmitted through parallel lines, so that the data transmission speed is greatly improved, but the length of the parallel transmission line is limited. Because the length increases, the interference will increase, and the data will be prone to errors.
What is a serial interface? It is what we often call a serial port, which means that data is transmitted one bit at a time in sequence 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 type of serial port. It is worth mentioning here that since people used to call UART ports serial ports in the early days, when people talk about serial ports, they generally refer to UART interfaces.

What are the advantages and disadvantages of parallel interfaces and serial interfaces?

1. Serial interface
Advantages: Fewer data lines are used, which can save communication costs in long-distance communication.
Disadvantages: Because only one bit of data can be transmitted at a time, the transmission speed is relatively low.

2. Parallel interface
Advantages: Because multiple bits of data can be transmitted together, the transmission speed is very fast.
Disadvantages: The number of data lines required depends on the number of bits of memory, so a large number of data lines are required, which is very expensive.

The difference between USART, SPI, and IICUART

interface:
UART (Universal Asynchronous Receiver/Transmitter) serial interface is the most commonly used communication technology for microcontrollers, usually used for communication between microcontrollers and computers and between microcontrollers.

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

IIC interface:
IIC (Inter-Integrated Circuit, integrated circuit bus) is also known as I2C, a two-wire serial bus structure used to connect microcontrollers and their peripherals. The main advantages of the IIC bus are simplicity and effectiveness.

Difference 1: UART is two-wire, one for sending and one for receiving, full-duplex communication is possible, and the number of lines is relatively small. Data is transmitted asynchronously, the timing requirements for both parties are relatively strict, and the communication speed is not very fast. It is most used in multi-machine communication.
Difference 2: Compared with the above UART, the SPI interface has an additional synchronous clock line. The disadvantage of the above UART is also its advantage. The timing requirements for both parties of communication are not strict. Different devices can be easily combined, and the communication speed is very fast. It is generally used for high-speed data communication between internal components of the product, such as large-capacity storage. Difference
3: The IIC interface is also a two-wire interface. It transmits data between two lines through complex logical relationships. The communication speed is not high and the program is relatively complicated to write. In general, it is mainly used to connect to small and easy memories such as 24C02 in single-chip microcomputer systems.
Note: SPI and UART can achieve full-duplex, but I2C cannot; I2C is a little slower than SPI, and the protocol is a little more complicated than SPI, but it also has fewer connections than standard SPI.