Reference
Last revision 2025/12/17
This article delves into the communication protocols of sensor modules, focusing on data output formats for distance and spectral data analysis, including UART communication and signal processing. It provides insights into algorithms for detecting multiple targets using spectral line amplitudes.
Communication Protocol Description
There are two protocols for data output, if the port 6 is grounded, the output is distance + spectral data, and it includes: data header, distance data, spectral data, and data tail. The format is as below:
0xff, 0xff, 0xff, 0x, 0x**, 0x##...0x##, 0x00, 0x00, 0x00**
The first three Oxff are data headers, then next 0x** is the upper eight bits in the 16 bits distance information, and the second 0x** is the lower eight bits. The 16 bits binary data represents the distance to the target. (unit: cm)
The first 0x## is amplitude of the first spectral line of the distance spectral lines, the next one is that of the second spectral line, and so on. There are 126 spectral lines in total. The amplitude ranges from 1 to 44. After post-processing, users can use these spectral lines to realize mutilple targets detection. The last three 0x00 are data tails, marking the ending of this group of data.
If the port is left floating, the output is the distance information. The format is as below:
0xff, 0xff, 0xff, 0x, 0x**, 0x00, 0x00, 0x00**
The first three 0xff are data headers. The next 0x** is the upper eight bits in the 16 bits distance information, and the second 0x** is the lower eight bits. The 16 bits binary data represents the distance to the target(unit: cm). The last three 0x00 are data tails, marking the ending of this group of data.
The format of the UART communication: 1 start bit, 8 data bits, 1 stop bit, no parity check.
Sensor Structure
Signal Processing Diagram
The operating principle of the sensor module is shown as below. First, amplify the tiny signal received by the sensor, then convert it into squarewave signal through comparision circuit and output digital signal 0,1 so that the singlechip could easily process the signal.
Algorithm of Multiple Targets
The port 6 is grounded, the output is distance + spectral data, and it includes: data header, distance data, spectral data, and data tail. The format is as below:
0xff, 0xff, 0xff, 0x, 0x**, 0x##...0x##, 0x00, 0x00, 0x00**
The first three Oxff are data headers, then next 0x** is the upper eight bits in the 16 bits distance information, and the second 0x** is the lower eight bits. The 16 bits binary data represents the distance to the target. (unit: cm)
The first 0x## is amplitude of the first spectral line of the distance spectral lines, the next one is that of the second spectral line, and so on. There are 126 spectral lines in total. The amplitude ranges from 1 to 44. After post-processing, users can use these spectral lines to realize mutilple targets detection. The last three 0x00 are data tails, marking the ending of this group of data.
For example: if the amplitude reaches the maximum peak, caculate the central point of the maximum peak. The central point will be the n-th data, then multiply by 0.126.
eg. If the spectral line amplitude forms peaks between 14th to 25th:
The distance of the point should be: (14+(25-14)/2)*0.126=2.457 (Unit:m)
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