LD2420 Radar Sensor Module 24GHz ISM Human Body Micromotion Millimeter Wave Radar Sensor Module AIOT Smart Home 8M 3.3V 50A

I've used two of these and they work well with home assistant and esphome. The recognized movement at a fair distance, say 30ft. Lots of different options to play with in the settings.

First - if you want to know how to hook this up and get started quickly, search for ld2420 on esphome's site. Not only will you get access to the code to see an example, but there's a very nice module page that describes all the CORRECT hookups, in English without any false/misleading information. The problem with this unit is, simply put, that two different versions exist with the same look and feel and depending on what version, the hookup is very different. The original/old version (< v1.5.3) is most likely what you'll find when googling and it will absolutely NOT work - wrong baud rate and wrong TX pins. The unit I got was the newer (>= v1.5.3) version. This means OT1 is the TX and not OT2 and the baud rate on this unit is only 115200 - not the weird 256000 for the old version. I've found no way to tell which version the unit is by looking at it. Only once you ARE connected can you query the firmware version, and then know how to hook up the wires, and well - you get it. It's a mess. Once hooked up to an old ESP32 using TX2/RX2 for basic uart functionality I finally got the results I wanted, the unit was working. Until then I spent days talking with the vendor - who was VERY responsive but only offered a full Chinese language only documentation. Nothing for the country they sold this in. For this reason I would suggest finding another vendor - but at least you know and with the external documentation like that on esphome.io you'll make this work. This site covers the parameters fine. To understand how this unit works under the covers, you seem to have to learn chinglish as you auto-translate documents in Chinese.

Worked perfect in my project, but it was hard to find an english version of the software for it.

Beautiful, all i can say

I bought several for a project and they work perfectly. The software was tricky to track down but I found everything I need. Google is your friend.

Interesting alternative to the LD2410C I typically use. Seems to fit a specific role of human presence detection, at least when used with ESPHome. So far works good to let me know when someone is in a room, up to 12-14 feet.

A wide variety of 24Ghz proximity sensors are available from this and other sellers here, and it can be tricky to pick which one you want to work with. For me, the biggest criteria is the connector, because a lot of them unexpectedly have a weird pitch that doesn't match usual breadboard wiring. This sensor is less capable than some, but it's also delightfully small and affordable, with a five pin connector that's relatively straightforward... .. relatively. As another reviewer helpfully stated, there are multiple versions of this sensor and pinouts vary. ESPHome's site is indeed a useful resource, and another useful bit of knowledge is that the OEM for this module is a major vendor called Hi-Link that has their own web presence. Searching for the full part number HLK-LD2420 should take you right to the product page there with a bit more information, including sensing distances/patterns to expect with it. The actual sensor module is great, but as with so many products like this, documentation leaves a lot to be desired. It would be nice to see the vendor provide at least one accurate datasheet in the product listing here, but at least information is out there if you go digging.

Highly suggest a tiny cardboard box over the plastic type of bag for packaging, kinda hard to see in the picture but since it’s presoldered headers they are ripped through the plastic and are bent. But other than that it seems the sensor itself self is working nominally. As stated in previous comment careful when connecting , pins may vary, and baud rate is a lil tweaked vs most guides you will find. Including gpt, it also gave lackluster instruction >_< not all wrong just common mistake between versions.