Baud rate identification method and device

Abstract

The invention provides a baud rate identification method and device, and the baud rate identification method comprises the steps: triggering a timer through an external interconnection function when the level of a receiving pin changes, and obtaining a first counting value C of a first level pulse width of a first level in a frame of data; determining the pulse width time of the first level according to the first count value C; determining the minimum pulse width time; determining the first bus baud rate and the number of the minimum code element time occupied by the first level pulse width ofthe first level; determining a relative error between the number of the minimum code element time occupied by the first level pulse width and the reference value; and comparing the relative error with a first threshold value, performing corresponding different processing according to different comparison results, and finally obtaining the correct baud rate. According to the Baud rate identification method, the correctness verification of the communication Baud rate can be realized so that the accuracy and the precision of the Baud rate are improved.

Description

technical field [0001] The invention relates to the field of serial bus communication, in particular to a baud rate identification method and device. Background technique [0002] Serial communication adopts the transmission method of data bits. Although it is slower than parallel byte communication, it has a simple structure and low cost. At least one transmission line is needed to complete the transmission. At the same time, the communication range can reach tens of meters. A relatively common form of communication. Since there is no timeline synchronization, devices using serial communication must use the same baud rate, otherwise they cannot communicate. Therefore, in the case of unknown baud rate, an identification method is needed to obtain this important parameter. [0003] In the prior art, there are two common baud rate identification methods. One is the exhaustive method, which changes the baud rate according to a fixed step size within a known range to test whet...

AI Technical Summary

Problems solved by technology

The first method is relatively simple, with high accuracy but low efficiency. It can only be measured when the other party initiates communication, which has strong limitations; the second method is fast, but there is an error in the minimum pulse width of the measurement. After the port is interrupted, the kernel first needs to perform the operation of pushing the stack to save the current operating environment, and then enter the interrupt processing function to read the count value of the timer and calculate the current pulse width time

The process of pushing the stack requires at least 20 instruction cycles. During this period, the timer is still counting, resulting in the measured pulse width time being larger than the actual value. The greater the bus baud rate, the greater the measurement error.

At the same time, every time an I / O port interrupt is triggered, it is necessary to enter the interrupt to read the count value of the timer. At a communication rate of 1Mbps, there is a situation where an interrupt is triggered every 1 microsecond, resulting in a large software burden and easy loss of waveform data. have an impact on the calculation results

[0004] The above two methods only use the minimum pulse width time to calculate the baud rate, and cannot automatically correct errors. In the case of large minimum pulse width errors and clutter interference or symbol superposition, the recognition accuracy is difficult to guarantee

Images