The Physical Layer of Asynchronous Serial Communication

In asynchronous serial communication, the physical layer provides the means for transmitting and receiving data over a physical medium. Asynchronous serial communication is a type of data communication that is used to transfer data between two or more devices asynchronously, meaning that the data is transmitted without the need for a clock signal. This type of communication is often used in embedded systems, networking, and computer hardware. In order for asynchronous serial communication to take place, the physical layer is responsible for providing the necessary hardware and software components that enable the transmission and reception of data. The physical layer is responsible for the physical interface between the devices, including the physical medium and the parameters of the communication such as the data format, speed, and flow control.

Physical Mediums

The physical mediums used for asynchronous serial communication vary depending on the application. Common physical mediums used for asynchronous serial communication include cables and wireless communication such as infrared, radio frequency (RF), and Bluetooth. Cables are often used for short-range communication, such as between two computers in the same room. For longer distances, wireless communication may be used, such as infrared or RF. In some cases, the physical medium may also be used as a form of communication, such as in the case of an Ethernet cable.

Data Formats

The data format used for asynchronous serial communication is typically 8-bit data in an asynchronous format, meaning that the data is transmitted without a clock signal. The 8-bit data is usually transmitted in a start-stop format, in which a start bit is sent to indicate the start of the data, followed by 8 bits of data, and then a stop bit to indicate the end of the data. The data format can also be configured to use different sizes of data, such as 7-bit or 9-bit, or to use different formats, such as synchronous or Manchester encoding. The data format can also be changed to accommodate different speeds, such as slow or fast baud rates.

Flow Control

Flow control is used in asynchronous serial communication to ensure that the data is transmitted without errors. Flow control is used to synchronize the sending and receiving of data and to prevent data from being lost or corrupted due to a buffer overflow. There are two types of flow control used in asynchronous serial communication: hardware flow control and software flow control. Hardware flow control is typically used in systems that require higher reliability, as it uses physical pins on the serial port to control the flow of data. Software flow control is used in systems that require lower reliability, as it uses special characters to control the flow of data.

Conclusion

In asynchronous serial communication, the physical layer provides the means for transmitting and receiving data over a physical medium. The physical layer is responsible for the physical interface between the devices, including the physical medium and the parameters of the communication such as the data format, speed, and flow control. The physical mediums used for asynchronous serial communication vary depending on the application, and the data formats typically used are 8-bit data in an asynchronous start-stop format. Flow control is used to ensure that the data is transmitted without errors.

04-Feb-2023

EducationComputer Science