1. Teachers Name : Suman Sarker Telecommunication Technology Subject Name : Microcontroller & Embedded System Subject Code : 6871 Semester : 7th Department : Electronics Ideal Institute Of Science & Technology (IIST)

2. LECTURE-09 CH-10 CH-10 8051 SERIAL COMMUNICATION

3. SERIAL COMMUNICATION A parallel connection between the microcontroller and peripherals established via input/output ports is an ideal solution when the distance between them is up to several meters. Otherwise, when it is necessary to establish communication on longer distances the parallel connection is out of the question. Serial communication is used instead.

4. Today, most microcontrollers have several different modules for serial communication built into them as a standard equipment. Which of these modules will be used depends on many factors of which the most important are: How many devices the microcontroller has to exchange data with? How fast does the data exchange have to be? What is the distance between devices? Is it necessary to send and receive data simultaneously?

6. One of the most important things about the serial communication is the Protocol which should be strictly observed. It is a set of rules which enables devices to correctly interpret data they exchange. Fortunately, the microcontroller itself takes care of this, so that the work of the programmer/user boils down to simple writing (data to be sent) and reading (received data).

7. SPI (SERIAL PERIPHERAL INTERFACE BUS)

8. The maximum data rate is higher than that in the I2C communication module.

9. UART (UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER) As its name suggests, the USART communication is asynchronous, which means that no special line for clock signal transfer is used. In some applications, such as radio connection or infrared waves remote control, this feature is crucial. Since only one communication line is used, both receiver and transmitter operate at the same predefined rate in order to maintain necessary synchronization. This is a very simple way of transferring data as it basically comes down to the conversion of 8-bit data from parallel to serial format. Data rate is not high, up to 1 Mbit/sec.

10. Next Lecture INTERRUPT OF 8051