The LD2410C is a mmWave presence/movement sensor that is really cheap, widely available and with a little help and unserstanding, makes a GREAT alternative to infra-red and ultrasonic detectors – and at the price is suitable for everything from human presence/movement detection in farly large rooms right down to light controls for storage rooms and cabinets.
I’ve spent AGES getting to grips with this device, not helped by projects that don’t actually work, other projects with code behind paywalls and more. Finally this week I stumbled on a video by an American chap who has done a great job of explaining the sensor and how to get started using it.
So, I started this quest using Apollo Automation devices like the Apollo Pro-1 mm Sensor and others from the same company and they are GREAT, but not cheap. Depending where you live and your budget, they could end up being just too expensive for widespread use throughout the home.
Then I started looking at the LD2450 and finally decided to try out the LD2410C after seeing various YouTube videos on the subject… but I hit so many dead ends – until now.
Here we are… I have a few LD2410C boards from AliExpress… simply put, they generally have a 5-way connector which includes ground, serial RX, serial TX, an output for a LED and VCC. For now we can ignore the output and focus on the 4 pins – ground is obvious, Vcc to 5v, RX and TX.
Next I grabbed an FTDI – a small board which plugs into your computer’s serial port (or a hub) and gives you 3v3 volt level serial RX and TX as well as 3v3 and 5v outputs – again available for next to nothing from AliExpress. Going to their CHOICE items it shoud be possible to get a couple of LD2410C devices and an FTDI for around 10 Euros including postage. Today I could generally chose serial devices like FTDIs with USB-C as I’m trying to standardise on USB-C. I tend to keep a few USB-A to C adaptors around as not all of my USB Hubs have USB-C connectors.
Anyway here is an older USB-A FTDI connected to an LD2410C sensor… the FTDI is providing the 5V power (around 79ma needed) and also serial RX and TX (connected to the LD2410c REVERSED – i.e. RX to TX, TX to RX.
And some detail… looking at the LD2410C, on the right you see the device – sensor side visible.Of interest, my device is about 20mm by 15mm. As you see I’ve connected TX, TX, ground and VCC. That’s it – for a mere couple of euros, this device, talking to an APP or a PC for example, can reliably detect human presence and movement. Doing something useful takes a little more work but one thing at a time.
On the active face you are viewing on the right here, the device senses from straight out for maybe a 60 degree angle and can work from mm to metres distance- though my experience so far suggests that maybe 20cm outwards works best without getting into adjustments. Oh and yes it gets warm in use. Below is a better view of my FTDI and the connections.
Hopefully the images above make the connections quite clear. I’ve done a video (below – embedded) to go with this article and hopefully between the two you’ll get a start on using these devices. As an aside, the LD2410C has a light sensor. Could be handy when used as a room presence sensor for lighting control to avoid turning on lights when it’s already bright out there. I’m not going into that here.
So a video fron Dronebot Workshop is what finally got me going – thanks to the owner for that – here’s his video for reference. There are two basic ways to talk to the LD2410C, Bluetooth or the serial pins. I’ll start with the latter. In a blog entry accompanying the above video, the writer mentions a free EXE tool available from the LD2410C manufacturer which uses Bluetooth. Here’s a 3-year-old Google Drive version of that tool. See the last item in the link above.
On my PC I rtied this tool and it works – see image on the right.
But that assumes you are using a PC… and it’s only SO useful – so I prefer the web-based online tool also described in the video. But first – the tool to the right and the web tool both need to talk to your FTDI via the serial port it creates when connected to your PC or whatever. Getting FTDIs to work is beyond the scope of this article – for me, they always seem to work “out of the box”.
I just plug them into a USB hub connected to my PC and a new serial port magically appears. That’s the port you’d connect to on the single .EXE program shown above right – and given the wiring arrangement I showed above, on hitting CONNECT at the default baud rate of 25600, you would immediately start seeing something happening.
However, I’m going to go straight to the web tool instead as I didn’t find the above THAT intuitive – similarly the web tool needs to connect to the serial port created by the FTDI. Here’s the link, this time not for a download but directly to the web-based LD2410 Configurator. And here it is in action – my video shows this all graphically and hopefully between this and the video you’ll see how easy it is to start with the LD2410C.
On loading up the page – and with your FTDI plugged into your computing device and to the LD2450C – this is what you should see.
I didn’t use the “Display Advanced connection options” box, I just picked a port as I showed above – and connected.
At this point I was up and running. Now we have the full main page of the LD2410 Configurator – showing live presence detection in the top left blue box and movement in the red box next to it – all as below. I go into detail in the video.
Simply watching the panel above and maybe playing with the controls on the sbove right, hopefully you should start to see what the LD2410C device is capable of (and it’s limits – the values do tend to jump about a bit so in practice a little filtering will be useful).
The next step which I’ll go into separately (as not everyone uses ESPHOME and Home Assistant) is to get that data out into a form that is useful. On DronebotWorkshop’s article he goes into using Arduino with the LD2410C device and also refers to the HLKRadarTool App for Android. If you look at the control screen above you can see that you can turn Bluetoioth on and off in the device from that web page. Turning it on I found the LD2410C device appear in the APP which I’d grabbed from the Android Playstore, but personally I decided to stick with the above web page and go off looking at the official ESPHOME web page where they go into code for the LD2410C.
See my video below – and try to avoid noticing that I’m not looking at the camera… I was too busy trying to get to grips with using OBSBOT Studio’s multi-window facilities.