Seed Studio Mr24bsd1 24ghz Mmwave Module User Manual

seed studio MR24BSD1 24GHz mmWave Module

Overview

This document focuses on the use of the radar, the issues that need to be addressed at each stage to minimize design costs and increase product stability and improve the efficiency of project completion. From hardware circuit reference design, radar antenna and housing layout requirements, how to differentiate between interference and multi-functional standard UART protocol outputs.
The radar is a self-contained space sensing sensor, consisting of RF antenna, radar chip and high speed main frequency MCU together with a module that relies on a stable and flexible superior algorithm architecture core to solve the user’s various scenario detection needs, which can be equipped with a host computer or host computer to flexibly output detection status and data, meeting several groups of GPIOs for custom development.

Principle of operation

The radar transmits a millimetre wave signal in the 24G band, the measured target reflects the electromagnetic wave signal and demodulates the transmitted signal, which is then amplified, filtered and processed by ADC to obtain the echo demodulated signal data. The amplitude, frequency and phase of the echo signal are decoded in the MCU unit, which ultimately enables the measurement of target parameters (breathing, movement, micro-motion, etc.) and scene evaluation.

Hardware Design Considerations
The radar needs to have a rated supply voltage of 4.9 – 6V and a rated current requirement of 200mA or more input under normal operating conditions. The power supply must be designed for a supply ripple of ≤ 100mv.

The power supply can be designed with the following circuit in mind

using the wiring diagram

Fig. 3 Schematic diagram of the radar module and peripheral connections

Antenna and housing layout requirements
PCBA: the radar needs to be kept ≥ 1mm higher than the other components Housing construction: need to maintain a distance of 2 – 5mm between the radar antenna face and the housing face
Housing detection surface: non-metallic housing, needs to be flat and straight to avoid curved surfaces which can affect the performance of the entire swept surface area.

Fig. 4 Schematic diagram of the radar module and peripheral connections

Static Protection
Radar products have electrostatic sensitive circuitry and are susceptible to electrostatic hazards, therefore they need to be adequately protected from static electricity during transport, storage, work and handling. When handling radar sensors, please wear anti-static gloves if possible.

Functional disturbances

Unoccupied state, abnormal output occupied
In normal conditions, the radar will accurately determine the presence of a sitting or sleeping body and output information on falls, breathing, vital signs etc.

• Radar scanning area is large, doorway, boarded wall next door movement is detected
  Adjustment method: reduce radar sensitivity, radar provides scene setting B. Radar underneath is facing a running air conditioner or fan Adjustment: adjust the radar position so that it is not directly in front of the air conditioner or fan
• Shifting objects caused by air conditioning winds
  Adjustment method: cotton, non-metallic objects will not cause false alarms, metal objects need to be fixed
• The radar is not fixed, vibration causes false alarms
  Avoid supporting shaking and vibration
• Occasional moving objects such as pets, birds, etc.
  As the radar measures micro-movements, the sensitivity is very high and this interference cannot be excluded
• Power supply interference, resulting in occasional false alarms
  Try to keep the power supply current stable and reduce ripple

Manned status, abnormal output unoccupied
Radar determines the presence of a human body by sending and receiving electromagnetic waves. The closer you are to the radar, the more accurate it is.

• Human body out of radar range
  Radar scanning range with adjustment of mounting angle. Radar measurement range, in different environments with different electromagnetic wave reflection areas, the scanning area will vary slightly.
• False output due to metal occlusion
  Excessively thick desks and chairs, metal seats. It will block the electromagnetic wave penetration and cause misinterpretation. C. Differences in scanning angles
  The radar does not scan the torso area. This can lead to false positives. D. Radar sensitivity is too low
  The radar offers parameter adjustment to increase sensitivity for improvement.

Functions in detail

Function point descriptions

Description of the output of the body motion amplitude parameter

Description of the agreement

This protocol is used to communicate between a 24G millimeter wave sleep detection radar and a host computer.
This protocol outlines the radar workflow, provides a brief introduction to the interface protocol component architecture and gives the control commands and data required for the operation of the relevant radar, with the serial communication defined as follows.

• Interface level: TTL
• Baud rate: 9600bps
• Stop bits: 1
• Data bits: 8
• Parity: None

Communication commands and parameter definitions

Definition and description of the frame structure

• Frame structure definition
• Description of the frame structure
  • Start code: 1 Byte, fixed to 0X55.
  • Data length: 2 Byte, low byte before, high byte after.
    Length = Data Length + Function Code + Address Code 1 + Address Code 2 + Data + Checksum.
  • Function code: 1 Byte
  • Read command: 0X01 Write command: 0X02
    Passive report command: 0X03
    Active report command: 0X04
• Address code: Address code 1
  indicates the function classification, address code 2 indicates the specific function.
  See the description of address assignment and data information.
• Data: n Byte
• Checksum: 2 Byte, low byte before, high byte after.
  CRC16 checksum is used, see Appendix 1 for reference code.

Description of address assignment and data information

Description.

1. The read/write command is for the upper computer to send commands to the radar.
2.  The report command is for the radar to send information to the upper computer.
3. Fall sensitivity is 1~10, default is 4, the higher the level, the more sensitive it is
4.  Human body sensitivity is 1~10 steps, default 7 steps, the higher the step, the more sensitive it is

Appendix 1: CRC check digit reference parsing codes

Appendix 2: Analysis codes for motor sign parameters

Historical version update notes