Method for achieving UART (universal asynchronous receiver/transmitter) communication interfaces through software simulation

Abstract

The invention relates to a processing method for transmitting and receiving UART (universal asynchronous receiver / transmitter) communication interface data through software simulation in an embedded system. The method for achieving a plurality of UART communication interfaces through software simulation, provided in the invention, comprises a data receiving method and a data transmitting method, wherein baud rate timing is accurately achieved by a timer interruption function of a timer, and both transmitting and receiving are performed under the control of timer interruption. In the invention, for simulating one UART communication interface, only one timer, two I / O (input / output) ports and one software interrupt are required. For simulating a plurality of UART communication interfaces, the timer and the software interrupt are shared. Therefore, once one UART communication interface is added and expanded, only two I / O ports are required to be added. According to the invention, UART communication interfaces can be achieved through software simulation.

Description

technical field [0001] The invention relates to a method for realizing UART communication through software simulation, in particular to a processing method for realizing the sending and receiving of UART communication interface data through software simulation in an embedded system. Background technique [0002] With the development of embedded technology and the diversification of embedded devices, the multi-computer system composed of embedded devices has made great progress. The serial port UART (Universal Asynchronous Receiver / Transmitter, universal asynchronous Receiver and transmitter) for data transmission, forming a complex master-slave communication network. [0003] In practical applications, it is often encountered that a master device needs to be connected to various slave devices at the same time, and the communication method between the master device and the slave device often uses the UART communication interface, which can only communicate one-to-one. Multip...

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Problems solved by technology

However, there are many shortcomings in its implementation method. 1. The method of judging the start bit of the data is to use the interrupt timing sampling monitoring method. The interrupt timing interval is 1 / 3 of the baud rate timing interval, and the received data is received at a baud rate of 3 times. Carry out sampling monitoring, which leads to too frequent timer interrupts, and in the case of no data transmission and reception, it is also necessary to regularly sample and monitor whether there is data in the communication bus, which consumes system resources; 2. The bit data sampled each time is the end position of the collected bit , the error tolerance of data reception is poor, and the accuracy rate is low, because when the timer precision is low or the bit data width error sent by the other party is large, there will be errors in the received data due to collection errors; 3. According to the description of the scheme, when sending For data, divide the timing by 3, and the interrupt timing interval is equal to the baud rate interval, so that one bit is sent for each timing interrupt, so it can be seen that in the process of sending data, the timing frequency cannot be 3 times the baud rate. The receiving data is sampled and monitored, and the data reception cannot be realized. Therefore, the full-duplex data sending and receiving communication mode cannot be achieved; 4. When simulating multiple UART communication interfaces and the baud rates of each communication interface are different, each communication interface needs to have a Timers, it is impossible to share a timer with multiple UART communication interfaces, so the number of UART communication interfaces that can be simulated is limited by the number of timers in the microprocessor, and usually the number of timers in the microprocessor is Relatively few; 5. When a byte of data is received, the received data is stored in the receiving FIFO queue in the timer interrupt service routine, which will cause the execution time of the timer interrupt service routine to be too long and reduce the accuracy of the system. Reduce the maximum supported communication baud rate

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