💬 Multi-Sensor: Temp/Humidity/PIR/ Leak/Magnet/Light/Accel

I just now posted Version 2. I changed the form factor to make it more compact. In addition, it now has a ground plane on the back. The whole thing is now roughly the size and shape of a CR2032 button cell battery.

The BOM for Version 2 is also a little different different: thru-hole rather than surface mount CR2032 holder and an (optional) 4-pin SMD header.

Nca78

Hello,

you have a mistake in your BOM for the nRF51822-04, it's linking to battery holders.

Would you consider changing the pads for the SMD header to this ?
http://www.molex.com/pdm_docs/sd/878980426_sd.pdf
This is what is recommended for this header that's available on Arrow, meaning free shipping for most of the world, as opposite to Digikey asking me for 75$ :)
Product on arrow is here. It is in fact smaller so it should fit on the pads you have put, but I suppose it will be easier to solder with the bigger pads.
https://www.arrow.com/en/products/0878980426/molex

There are some 2x5 1.27mm IDC connectors on AliExpress here but they have smaller inside space than the one you choosed so I'm a bit worried...
https://www.aliexpress.com/item/20Pcs-0-050-1-27-mm-2x5-Pin-10-Positions-IDC-Male-Box-Header-Dual-Row/32813323776.html

Nca78

Also, what about moving the led to the center next to its resistor, it would leave enough space to squeeze in a SOT 23 ultra low power hall sensor and it's 100nF capacitor.

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

Also, what about moving the led to the center next to its resistor, it would leave enough space to squeeze in a SOT 23 ultra low power hall sensor and it's 100nF capacitor.

Thanks for the suggestion. What would the hall sensor be used for?

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

you have a mistake in your BOM for the nRF51822-04, it's linking to battery holders.

Thanks for pointing that out. I've fixed it now. Also, the link for the CR2032 thru-hole holder didn't post correctly to the correct entry, so I've fixed that too.

Nca78

@NeverDie said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

Thanks for the suggestion. What would the hall sensor be used for?

For a door sensor. This PCB is small enough to be hidden inside a door edge, if you put it on top with a small magnet in the frame it's completely invisible and you've got that mythical 100% WAF level :D

There is a cheap version, TLE4913 that's available on AliExpress (less than 2$ for 10 with shipping), it's consuming around 4uA so it's not extremely energy efficient but you can't beat the price on AliExpress.
https://www.aliexpress.com/item/in-stock-can-pay-TLE4913-4913-SOT-23/32823499977.html

Then there's the DRV5032 from TI that had the lowest power consumption a few month ago when I bought it, it's 0.5$ on Arrow and needs only 0.54uA in the FB (5Hz) version
https://www.arrow.com/en/products/drv5032fbdbzr/texas-instruments

And now I see the si7201 for 1$ on Arrow, using only 400nA.

My choice would still be for the DRV5032, but the good news is all those sensors are using the same package with the same pin assignment. There are a few others (including one that scalz used in one of his design) also with the same pin assignment.

NeverDie

Hmmm.. I don't presently have a need for a door open/close sensor. However, if I could use it to tell me whether the deadbolt is locked or unlocked, that would be useful.. Maybe if I epoxied a magnet on the tip of the deadbolt? Or is there some other, better way?

Nca78

@NeverDie said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

Hmmm.. I don't presently have a need for a door open/close sensor. However, if I could use it to tell me whether the deadbolt is locked or unlocked, that would be useful.. Maybe if I epoxied a magnet on the tip of the deadbolt? Or is there some other, better way?

Yes you can use it for that. Maybe magnetizing the deadbolt could work too ?

NeverDie

There may be enough space within the deadbolt lock cavity itself to mount a wireless sensor there. It's something I've wanted for quite a while but until now I've never had (and couldn't find) something small enough to fit in there.

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

Maybe magnetizing the deadbolt could work too ?

Great idea. :)

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

There are some 2x5 1.27mm IDC connectors on AliExpress here but they have smaller inside space than the one you choosed so I'm a bit worried...
https://www.aliexpress.com/item/20Pcs-0-050-1-27-mm-2x5-Pin-10-Positions-IDC-Male-Box-Header-Dual-Row/32813323776.html

Those are thru-hole, not SMD.

I actually prefer thru-hole for these 10-pin connectors--much easier to solder--but I'm afraid the resulting solder/pin bumps on the back side would make the CR2032 holder sit a bit crooked (?), if you know what I mean.

That said, I've found buttoncell holders that have little plastic alignment pins on them (meant to fit into alignment holes) that could jack up the holder a bit if the alignment holes were omitted. Maybe then there'd be enough clearance.

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

Would you consider changing the pads for the SMD header to this ?
http://www.molex.com/pdm_docs/sd/878980426_sd.pdf
This is what is recommended for this header that's available on Arrow, meaning free shipping for most of the world, as opposite to Digikey asking me for 75$
Product on arrow is here. It is in fact smaller so it should fit on the pads you have put, but I suppose it will be easier to solder with the bigger pads.
https://www.arrow.com/en/products/0878980426/molex

Yes, but what's holding me back is that I'm worried I might plug it in backward and possibly fry something. Haven't really thought it through though. Maybe there's actually no risk if that were to occur? The one and only advantage of the box header is that I can't accidentally plug it in wrong.

But I've been thinking along similar lines. I've already ordered and received this from your favorite source:
https://www.aliexpress.com/item/25-pcs-2x5-P-10-Pin-1-27-mm-Male-PCB-Header-Dual-row-Straight-PCB/32762274575.html?spm=a2g0s.9042311.0.0.ltfMrU

and

https://www.aliexpress.com/item/20-Pcs-Per-Lot-Pitch-1-27mm-Female-2x5-Pin-10-Pin-Double-Row-SMT-SMD/32591554432.html?spm=a2g0s.9042311.0.0.ltfMrU

@Nca78 Would those be equivalent to the Molex that you linked to, or would the Molex you linked to be better?

NeverDie

@Nca78 said in 💬 CR2032 Small Wireless Temperature-Humidity Sensor:

This is what is recommended for this header that's available on Arrow, meaning free shipping for most of the world, as opposite to Digikey asking me for 75$

In any event, these should work the same as the Digikey ones: https://www.aliexpress.com/item/10-Pcs-SMT-Box-Header-1-27mm-2x5-P-10-Pin-dual-row-Straight-Male-surface/32787313045.html?spm=2114.10010108.1000013.3.2b0cc1askqPA1&traffic_analysisId=recommend_2088_2_90158_iswistore&scm=1007.13339.90158.0&pvid=a04bdf37-bc7e-4b9e-850f-b5e285ab3ff0&tpp=1

NeverDie

Also, there may be a clearance problem with the current PCB layout. Not sure if a si7021 or BME280 were installed whether or not it would overlap or collide with the 10-pin box connector. So, that may be yet another reason to do a Version 3.... Didn't notice it as a possible problem until after I had posted Version 2. A workaround would be to install the si7021 or BME280 upside down, so that the board points outward rather than inward. That might be acceptable also. It would somewhat defeat the compactness objective, but the antenna has to stick out a bit anyway, so that's already happening to some degree.

NeverDie

Does anyone know where we can get the connector that's used on the nRF52 DK? It would seem to be ideal: 10-pin, and keyed, but no box surrounding it.

💬 Multi-Sensor: Temp/Humidity/PIR/ Leak/Magnet/Light/Accel

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