MLX90621 hardware

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GGL
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Joined: Wed Jun 21, 2017 9:03 am

MLX90621 hardware

Post by GGL » Wed Jun 21, 2017 9:27 am

Hello everybody,
Someone has experience with "Melexis MLX90621 (16x4 IR array) + Micropython" board?
I want to make a "human body detection" (presence detector).

Thanks in advance.

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deshipu
Posts: 1316
Joined: Thu May 28, 2015 5:54 pm

Re: MLX90621 hardware

Post by deshipu » Wed Jun 21, 2017 4:36 pm

This is oddly specific. I don't have any experience with this particular sensor, but looking at the datasheet at https://www.melexis.com/en/product/MLX9 ... -Low-Noise is seems that it should be relatively easy to implement an I²C driver for communicating with it. However, it seems that its principle of operation is not trivial, and while you can get the data from it easily, actually doing something useful with that data (and before that, calibrating the sensor properly) may be an art of its own. In any case, it should be doable.

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deshipu
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Re: MLX90621 hardware

Post by deshipu » Wed Jun 21, 2017 4:37 pm

On the other hand, have you looked at the simple PIR sensors? They could detect human presence much easier.

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wminarik
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Location: Montréal, Canada

Re: MLX90621 hardware

Post by wminarik » Wed Jun 21, 2017 10:52 pm

Over at OpenMV they have a thermal shield that uses the MLX90621:
https://openmv.io/collections/shields/p ... ile-shield
with the Micropython code in their GitHub repository:
https://github.com/openmv

I've used the MLX90621 with the code and it works well.

GGL
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Joined: Wed Jun 21, 2017 9:03 am

Re: MLX90621 hardware

Post by GGL » Thu Jun 22, 2017 6:48 am

Thanks for yours answers and opinions.
deshipu: In my case the PIR sensor is not be able, because I need detect the presence of human body, and the PIR only detect movement through the temperature changes.
wminarik: I will check the OPEN MV project, but I think that this solution (OPEN MV camera + MLX90621 module), is expensive for me.

Thanks.

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pythoncoder
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Re: MLX90621 hardware

Post by pythoncoder » Thu Jun 22, 2017 7:47 am

The thermal shield info says "This product is no longer sold any more.". However the OpenMV cam has an IR LED so it should be able to do presence detection in the dark simply and in MicroPython.

But I'm with @deshipu on this: PIR sensors are the security industry standard way to do the job.
Peter Hinch

GGL
Posts: 5
Joined: Wed Jun 21, 2017 9:03 am

Re: MLX90621 hardware

Post by GGL » Thu Jun 22, 2017 8:04 am

Thanks pythoncoder,
I'll check about OpenMV CAM with IR LED solution.

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Roberthh
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Location: Rhineland, Europe

Re: MLX90621 hardware

Post by Roberthh » Thu Jun 22, 2017 10:57 am

To act just as a motion detection, a PIR sensor is sufficient. I tried a few, and ended up using sensors of the AMN-Series of Panasonic (e.g. AMN31111J). A little bit more expensive than the usual 4-6$ models from China, but very easy to integrate (Vcc 3..6V, open drain output), many different variants and very reliable.
But this device here aims at a precise measurement of the temperature, and that makes it different to the usual PIR sensor, and opens other use cases. But I see, the price is ~45€ in low quantities.

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mcauser
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Re: MLX90621 hardware

Post by mcauser » Fri Jun 23, 2017 1:05 am

If you need penetration through plastic, walls, etc, have a look at some of the cheap doppler microwave sensors now available.
eg. HB-100, HW-MS03, WB3-12, XYC-WB-D, HFS-DC06, RCWL-9196 and RCWL-0516

They operate on 2.4GHz, 5.8GHz or 10.5GHz, so watch out for wifi interference.

The guy with the Swiss accent (Andreas Spiess) has a comparison video:
https://www.youtube.com/watch?v=9WiJJgIi3W0

Roger Clark reviews RCWL-9196 and RCWL-0516 radars:
http://www.rogerclark.net/investigating ... r-modules/

GGL
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Joined: Wed Jun 21, 2017 9:03 am

Re: MLX90621 hardware

Post by GGL » Tue Jun 27, 2017 10:54 am

Thaks at all,
Roberthh: I will check the "AMN-Series of Panasonic"
mcauser: thank you for another line of instruments (doppler microwave)

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