¿Tienen que ser coherentes los tiempos de los bits de datos de la comunicación serie?

Qué es la comunicación serie

Serial communication is of great significance to microcontrollers, and requires a small number of cables and simple wiring, so it is widely used in remote data transmission. To put it simply, the data exchange between the host and peripherals, such as the communication between the computer and the printer, and the data exchange between the host and the host, such as QQ communication, are all implemented by serial communication.

To achieve serial communication, three wires are needed to complete the entire process: ground wire, sending and receiving. Since serial communication is asynchronous, the port can send data on one line and receive data on another line at the same time. The other lines are used for “handshakes”, indicating friendship. The whole process is like getting water from a wooden bucket. The sender opens the lid of the bucket and pours water into the bucket. In other words, who and what you want to send the data to. When the transmission is completed, the receiver needs to get water from the bucket. When the water is finished, a message will be sent to the sender telling him “I have finished receiving”. It is equivalent to a printer. Before printing , it will ask the computer whether to print this data. If yes, start the printing job; if not, stop printing. Therefore, in general serial port communication, there must always be an active party and a passive party, and when the two transmit data, there will be a certain negotiated data format. Both sending and receiving must be done according to this data format.

¿Tienen que ser coherentes los tiempos de los bits de datos de la comunicación serie?

Serial communication uses serial ports. Commonly used serial ports include RS232, RS485, and RS422. The so-called serial communication means transmitting one data bit at a time. That is to say, at a certain point in time, only one level will be present. Various levels are presented once and may last for a certain unit length. We call this kind of communication serial communication.

For example, we want to transmit certain binary data: “10 10 10 10”. This byte has eight bits. When serial communication transmits a byte, the transmission starts from the low-order bit on the right. It takes eight units of time to transmit this byte, and the time for each bit can be set independently. If the sender sets the time of each bit to M, then the receiver also needs to set the time of each bit to M. If the receiver sets the time to N, the data can also be received, but the received data is inconsistent with the source data. If the data is inconsistent, the data communicated through the serial port will be meaningless. Therefore, the number of bit times of the sender and receiver must be consistent.

Keywords in this article: RS485 to Ethernet