HC-SR501 motion sensor

[bjornhallberg]

Since I want to make my MySensors project all about security, I'd like some input on the selection and operation of the default Ebay motion sensor - the HC-SR501. Some question that have been bugging me:

1. Is this sensor reliable? I noticed from the specs that the detection range / cone seems a bit narrow? Will it last outdoors if properly protected and sealed? What sort of lifespan does it have? Does it deteriorate over time?

2. Are there other better modules available if you're willing to pay a little more? I've found none so far ...

3. What about power consumption then? 65uA or <50uA are figures being thrown around. I've seen mentions of 40 uA at 5V while idling and 150 uA when motion is detected. That shouldn't be too hard on batteries? What about when you run it on 3.3V and bypass the regulator, surely that would make some difference?

[BulldogLowell]

@bjornhallberg said:

I noticed from the specs that the detection range / cone seems a bit narrow?

I am using them indoors to detect motion in/out of rome and hallways. Seems reliable. I mainly use them in wall outlets to detect legs moving by.

[marceltrapman]

@BulldogLowell said:

I am using them indoors to detect motion in/out of rome...

Wow, how many of these puppies do you use??? :-D

[BulldogLowell]

@marceltrapman

two kids rooms to turn off lights (that they seem incapable of doing)

hallways X 2 and one in the garage I just put there

[marceltrapman]

@BulldogLowell said:

@marceltrapman

two kids rooms to turn off lights (that they seem incapable of doing)

hallways X 2 and one in the garage I just put there

Still many, I have only 2 one for the kitchen and one for the bathroom.

But... I was referring to the fact that you wrote 'rome' instead of 'room' :)

[BulldogLowell]

@marceltrapman said:

@BulldogLowell said:

@marceltrapman

two kids rooms to turn off lights (that they seem incapable of doing)

hallways X 2 and one in the garage I just put there

Still many, I have only 2 one for the kitchen and one for the bathroom.

But... I was referring to the fact that you wrote 'rome' instead of 'room' :)

hehe I missed that.

My kids live in Rome, so to speak, and live like senators!

[marceltrapman]

@BulldogLowell :)

So, the sensors solve the behaviour of the senators...

[Yveaux]

@marceltrapman said:

So, the sensors solve the behaviour of the senators...

This reminds me of an old thread before the crash. It discussed about the name of a sensor/actuator node and we came to the conclusion that sensuator could easily be mis-interpreted for a whole different type of device ;-)

However senator seems like a nice contraction of sensor and actuator! +:100: !!!

[marceltrapman]

@Yveaux said:

However senator seems like a nice contraction of sensor and actuator! +:100: !!!

Good one!

[Bandra]

Does anybody who has bypassed the onboard regulator on the HC-SR501 be able to post up a photo of where you soldered?

I thought it was pretty simple and soldered my 3.3V lead to the leg on the 7133. It seems to power up (at least, so says my voltmeter), but the trigger (output) pin just goes high immediately and never changes. So on my sensors network it is just constantly triggering (even when there's no motion).

I'm doing something wrong, but not sure what it is. Any hints?

[Yveaux]

@Bandra see my investigations for this sensor here (also see the scope plus above) : http://forum.mysensors.org/topic/250/how-do-i-use-the-interrupt/19

Removing the regulator does not influence the power consumption, so just leave it connected.
The 3v3 should be connected to the inner pin of the retrigger jumpers, not the regular 5v supply pin.

[lininger]

@Bandra said:

Does anybody who has bypassed the onboard regulator on the HC-SR501 be able to post up a photo of where you soldered?

Here is how id modified the sensor.

Does anyone know if the Mini version also has such a place as the SR501?

[Bandra]

Thanks for the replies, @lininger and @Yveaux. Do you bridge H and the centre solder pad?

Here's my solder effort:

I checked with my multimeter, and soldering a 3.3v wire onto the 7133 leg gets 3.3v to the H solder pad. So I'm pretty sure that I've done the equivalent of yours.

And yet, it doesn't seem to work. After a few seconds my output pin just goes high and never drops low. I've tried to tune the pots but it makes little difference.

Just wanted to check that at least I got the power right. Thanks guys!

[Yveaux]

@Bandra according to its specs it takes a minute or so to startup, but you probably waited longer, right?

[Bandra]

Yeah, the sketch I found waits for it to warm up. I'll increase the warmup period and try again. Thanks for the suggestion!

[Bandra]

Moved my solder point to the H pad. Also bridged the H pad with centre pad. All works now. Thanks everyone!

Interesting observation. The motion sketch works very well. But when I try my multisensor sketch it always reads high and keeps triggering. Must be a problem with taking too long in the interrupt. I recall a small discussion about that. Time for some searching...

[Yveaux]

@Bandra If you configured the interrupt LEVEL triggered (either low or high) you have to wait for the signal to change in the interrupt handler (or e.g. disable the interrupt in the interupt handler) or it will enter the interrupt handler immediately again on exit.

[Bandra]

Thanks @Yveaux
I think I'm pretty safe there because I'm relying on the MySensors library to do the interrupt [ie, the sleep(int, int, long) method]. In that method, the library disables the interrupt itself [in MySensor::sleep it performs a "detachInterrupt(interrupt);" ]

I got it going reasonably well by doing two things. I moved the code that tests the D3 pin towards the beginning of the loop(). This helps avoid flapping (ie, if the pin fell low between the time the the interrupt was triggered to the end of the next loop() then it might cause flapping). I also changed my sleep call from:

sleep(INTERRUPT, CHANGE, 30000)

to

sleep(INTERRUPT, RISING, 30000)

This way, a flapping motion sensor doesn't affect me as much. Those two changes worked a treat. My multisensor sketch works well now!

Thanks again for all your advice on this forum.

[Homer]

@BulldogLowell said:

I am using them indoors to detect motion in/out of rome and hallways. Seems reliable. I mainly use them in wall outlets to detect legs moving by.

I'd really like to see this. Having the sensor plugged into a wall socket would be perfect! Would you mind sharing how you did this? ie what case etc, so it looks good?

I have searched, but didn't find anything.

thanks

[BulldogLowell]

@Homer

check out this thread