The Design Of UART Of 8-Bit MCU

UART is used to transform the data from parallel format into serial format, or to transform the data from serial format into parallel format. Becoming more powerful and having stronger applicability, MCU is used in more and more areas. Based on the needs of communication in applications, now most MCU chips are integrated with UART function. Not integrated with UART function, MCU chip have to achieve UART functional with the help of software and it will take up CPU time with more cost. It also make it more complex for the data transmission between the MCU chip and other processor. In order to make MCU have a high flexibility in communication, we can have the MCU directly integrated with UART function under its design. It also can ensure the reliability and stability of MCU communication.Now digital IC is basically designed in the design of top-down. Hardware description language is used to describe the function of the hardware layer by layer, and the software of simulation help do the function verification of the design layer by layer.When the function is verified, the synthesis tools help synthesize the modules which are needed to be translated into concrete circuits into gate-level netlist corresponding to the device library. Then automatic placement and routing tool converts the netlist into the actual circuit wiring structure which is needed.Data communication protocol should be followed during data communication, so as to ensure the accuracy and reliability of data communication. In the process of receiving data, UART will receive the external serial data sent into, and a receiving interrupt flag will be produced when reception is completed. The data is transformed from serial format into parallel format and its correctness can also be verified.In the process of sending data, UART will transform the data from parallel format into serial format. A start bit will be added in front of the valid frame data, also a optional parity bit and a stop bit will be added behind the valid frame data. A sending interrupt flag will be produced when sending is completed and its correctness can also be verified.This UART with high-precision baud rate generator designed in this thesis is integrated on an 8-bit MCU. There are four operating modes available to meet the communication needs of different application environments. In mode 0, 8 bits are transmitted or received synchronously, and the baud is fixed at 1/12 of the oscillator frequency. In mode 1, 10 bits are transmitted or received asynchronously, and the baud is generated by Timer 1 or Timer 2. In mode 2, 11 bits are transmitted or received asynchronously,and the baud is fixed at 1/32 or 1/64 of the oscillator frequency. In mode3, 11 bits are transmitted or received asynchronously, and the baud is generated by Timer 1 or Timer2. Its receiving interrupt flag and sending interrupt flag is independent and it can do the parity check. In asynchronous mode, it is full-duplex and it can also work in multi-master communication mode. Through simulation and testing, the correctness of the UART function on an 8-bit MCU is verified. It can meet the needs of the application.With the development of the integrated circuit industry, IC design technology becomes more advanced. The importance of low-power design has become increasingly evident.This UART about low-power design just did a little, so the design can be further optimized and explored in this area.