Proximity Sensor Videos

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Donavan Rajawi

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Aug 5, 2024, 1:50:25 PM8/5/24

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Todaywe will look at another proximity sensor, the RCWL-0516. This device works using microwaves and the Doppler Effect to detect the presence of humans (and other creatures) in a room. It is inexpensive and can be used by itself or in conjunction with an Arduino.

If you have ever heard the sound of a train as it races towards and then away from you, or an ambulance as it races down the road, you will have heard the siren frequency changing as the object approaches, passes, and moves away from you. That is the Doppler Effect in action.

I will show you how to use the RCWL-0516 on its own, both by itself and with an optional light sensor. You'll see that because it uses microwaves it is still operational even when encased in a plastic enclosure.

In that respect I would like to get some more qualified opinion. Could I use these devices inside my home always active (lets say to control light or as a burglar alarm etc.) and not be concerned at all by their radiation.

If you're terribly concerned about the radiation, then just make a small, thimble shaped aluminum foil (double thickness) hollowed out to about 2-3 cm deep and stick the device in the bottom with the wires exiting behind.

You can then put one on each side of the door of interest and the cone will limit the area of exposure to directly below the sensor. By having one on either side of the door, you can tell (from which one triggers first and which follows) whether the person is entering or leaving the room. You can then adjust the lights accordingly.

No, I am not terribly concerned about the radiation, I just feel better being safe than sorry. Then it is not only about me or a prototype, but also in respect to implementing this kind of tech in a commercial product. I believe such effects just in general should be taken more seriously and manufacturers should be more serious about those.

With radiation, wireless, G4/5, whatever, in my experience some people react very sensitive to it, others not. And if any secondary effects exist, they might never get identified or only decades later.

I guess that is why in my first post I have called this a kind of controversial subject. Of course, I am surrounded by radiation of multiple kinds and happily using all this over the air technology. So I am by no means just against it. I just believe it should be taken into account.

@activ8me Remember the already tiny amount of radiation reduces as the inverse square. If it is x at 1cm then it is 1/10,000 at 1 meter. A rough calculation of the wattage not allowing for any losses is to measure the input power. I believe it's 5V and IIRC it's powered by a pin so maybe 20 ma making input wattage of 100 milli Watts and at 1M is 10 micro watts (micro is millionth)

@inq I don't have a scope, but my reading is that the output pin has a range of 0 to 3.3v. I suspect it is possible to translate the voltage to distance. Going further if you want velocity, then two samples delta t apart called v1 v2 v3 etc, then acceleration is the delta t between v's.

@yurkshirelad, @zander - If I understand the video correctly, it's doing Doppler-shift not range finding. I.E. When he moves his hand in front of it, it lights up, but if hand is kept still in front of it, the LED will go off. But that is a great find that its voltage changes on that "out" pin! ?

I don't recall Bill referencing this github link, so I might have just stumbled across it. I'm reading through it now. It also uses the issue tracker (up to 41) as a mini-forum of questions.

Since I upgraded my iPhone 7 Plus to iOS 11.3, the proximity sensor is ridiculously sensitive. For example, if the phone is sitting face up on the table and I get within 3 inches of the top half of my phone (by the camera) the screen turns off. Any thoughts on how to fix this or turn off this "feature"?

What are you doing at the time that is turning off when the proximity sensor is turning off the screen? I can read you are "within 3 inches of the top half of the phone", but what are you doing on the phone at the time?

The proximity sensor should be disabled except when you are on a phone call. If the screen is turning off at any other time when you are not on a call there is something else wrong, and most likely it has nothing to do with the proximity sensor. It thus has nothing to do with sensitivity. If restarting the phone doesn't fix it (Restart your iPhone, iPad, or iPod touch - Apple Support), Try restoring iOS on your phone: Restore your iOS device from a backup - Apple Support

I could have been doing anything, such as checking email, finished a phone call, checking my calendar, playing a game, looking at home screen...it doesn't matter. If I put my hand within a few inches of the screen while it is on, the screen turns off, and when I move my hand away the screen comes back on.

I understand the intended use case for this feature (turn screen off when you put the phone against your ear during a call) but the sensitivity is too much now and it interferes with the usability of the device.

When you are not looking at the phone and cover the front of it, the screen will blank under certain circumstances. Seems this may be a battery saving act. If you turn the phone face down, the screen will also not light up for any notifications, etc., unless you pick the phone up and then look at it. I believe that is part of the Attention Aware features, and that switch is available in the Settings>Face ID and Passcode section. Can be too sure, as I've never tried changing the setting on my device before. Also, if the phone rings, when you pick it up and then look at it, the screen will dim and the volume will automatically turn down, which is part of that Attention, since the phone "knows" that you are looking at it and it doesn't have to be that bright/or ringing loudly.

However, I just tested my iPhone X against what you are saying. I turned the phone on, then opened the calendar while the phone is lying on the table and wiped my hand all around the phone and it has not turned off at all. Check that one setting I mentioned and see if you have it on or off. Also, what setting do you have Auto-Lock on?

You will have to wait to see if another user with an iPhone 7 can test their device to duplicate the behavior you describe. Have you tried any troubleshooting to see if you can change this behavior? You can also make a Genius Bar appointment to have the device examined by Apple if you have an Apple Store close by to see what they have to say.

It would probably be the quickest if you have one close by and can get an appointment. Otherwise it would require you to try a number of other troubleshooting steps. Again, I don't have a 7 here at home to test with. My wife has an iPhone 7, but she is at work right now and won't be home for several hours.

iPhone X here and I am having the exact same issues as described above. This has not been an issue for me until a couple days ago - it is not incredibly sensitive, regardless of application in use and almost always whilst I am looking at my device.

I only noticed it yesterday while I was in landscape in the calender. I was on my back on the couch and every time I used my hand around the sensor (from close to approx 3inches) it would cut out as per a phone call.

While turning the phone all the way off and back on does resolve the problem, the issue does reoccur. Which necessitates me turning my phone all the way off and back on again. Apparently there was some sort of bug.

I had this same problem and it was very annoying, just using the phone in a normal way and passing my hand over the sensor would trigger the screen to go black. I fixed this by doing a hard reset on the phone, holding both the "power" and "home" buttons simultaneously until the Apple logo appears, then release. HTH

I am following this tutorial to make a automatic "bed levling" addition to my 3dprinter.

I have everything hooked up correctly (as shown in that video, around Monoprice Maker Select Auto Bed Leveling w Stock Board - YouTube )

I'm not into chasing down videos. Do you have a wiring diagram maybe, and a datasheet for the sensor? One thing for sure, if you try to pump 300mA into Arduino, Arduino won't be happy (probably you not also).

DKWatson:

If the Uno is powered via the power jack (not the USB) you could connect the brown sensor wire to the Vin pin to get more with in the operating voltage range. The sensor output is NPN open collector so it should not be a risk to the Uno.

6v6gt:

After I bought a genuine screen replacement from here ,I installed just as described by the video,after doing so I realized my proximity sensor wasn't working and my adaptive brightness was no longer adapting

I think you're right about removing that black sticker. Don't feel bad, I doubt I'd have thought to remove it myself since it doesn't at first glance look like just a protective sheet. Here's my reasoning for agreeing with you.