HLK-LD1115H-24G is the high sensitivity 24GHz millimeter wave human presence detection radar module
The module can penetrate the non-metallic shell without opening. Common materials include plastic, glass, wood, ceramics, etc.
Pin interface definition: (It is recommended to use a 2.54mm spacing row pin connector for the interface)

VCC: 5V power supply
GND: Grounding
VO: Inductive output pin (optional)
URX: TTL serial port reception
UTX: TTL serial port transmission

You can debug and test HLK-LD1115H-2.4G on a computer through a serial port assistant.
Use any serial Debugger. Baud 115200, 8-bit data bit, 1-bit stop bit, check bit and flow control are None, and ASCII is selected for reception setting,
Select ASCII for sending settings

When the radar detects significant motion, it outputs mov, * * * * *. (The second digit represents the signal strength)
When the radar detects a stationary state or small amplitude movement of the human body, it outputs Occ, * * * * *. (The second digit represents the signal strength)
When the radar cannot detect the target, it stops outputting. Users can set a certain delay in the upper layer to avoid frequent unmanned states when weak signals are present. (The first number represents the position of the spectral line, which can be directly ignored by the user)

Note: The module takes approximately 15 seconds to start, and data output begins 15 seconds after being powered on. Because the module makes existence judgments by accumulating signal features for a period of time, when personnel disappear from the radar detection range, the radar will continue to accumulate signals for a period of time, so the radar will stop outputting after a delay time.