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Data transmission of asynchronous serial communication controlled by group bus communication

2020-11-07 20:56:04 Qishan

In the computer , Bus communication control mainly solves how to know the beginning and end of transmission , And how to coordinate and cooperate with each other .

There are usually four ways : Synchronous communication 、 asynchronous communication 、 Semi synchronous communication 、 Separate communication .

In asynchronous communication , There are two ways : Parallel transmission 、 Serial transmission .

In asynchronous serial communication , There is no synchronous clock , There is no need to transmit synchronous signals in data transmission . To confirm the transmitted character , The agreed character format is :

1 Starting bits ( Low level )、5~8 Data bits ( Such as ASCLL Code for 7 position )、1 Two parity bits ( For error detection )、1 or 1.5 or 2 Stop bits ( High level ).

1) The start bit is followed by the lowest bit of the character to be transmitted , The parity bit should be the highest bit of the transmitted character , In fact, it is to put the binary number of characters upside down , The end of the whole character is a high level stop bit .

2) The start and end bits form a frame , The interval between two frames is arbitrary , This part of the interval is called the free bit ( High level ).

3) The less free bits between two frames , The higher the data transmission rate .

Example : Drawing shows how to send hexadecimal data by asynchronous serial transmission 95H. The character format is required to be :1 Bit start bit 、8 Digit bit 、1 Bit parity bit 、1 Stop bit . Let's say that every second 120 Data frames , Try to calculate the baud rate 、 Bit rate .

According to the character format given by the title , A frame contains 1+8+1+1=11 position

So the baud rate is :(1+8+1+1)*120=1320bps=1320 potter

The bit rate is :1320*(8/11)=960bps

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