Sensebender Micro

[Heinz]

@nivoc
I can confirm your results: I am running two different sensors in the same room next to each other. The sensebender is always above the dht-22. Right now it is
52% to 47.8% rel. humidity, while the temperature is 17.8 to 17.9 (which is nearly equal).

[nivoc]

@tbowmo No I haven't baked yet. I will try that but not in the next two weeks. But I will report back.

[nivoc]

But I tested tonight with distilled water - so should be exactly 100%. And again (I didn't know that thats possible) I got 104 and 107% so slightly above (still increasing). Thats great b/c that means all values are about 7-8% too high.
At 33% the reading was about 40%
At 75% the reading was about 83%
At 100% the reading was about 106%

So reading minus 8% gives a pretty accurate result. In the next few days i will test 3 more sensbender.

Distilled Water (100% expected):

[bjacobse]

Read the spec for the humidity sensor used in the sensebender (Si7021 integrated humidity / temperature sensor.)
Precision Relative Humidity Sensor: ± 3% RH (max), 0–80% RH
To my reading this is actually 6% wrong reading to one of the sides - so when you are measuring yours to be 8% off, is caused that you are using the device outside of humidity range 100% and max is 80%

Link to spec:
https://www.silabs.com/Support Documents/TechnicalDocs/Si7021-A20.pdf

What I want you to know, if your device is reading within 6 % of the value - it's still reading correct. and when you compare ex DHT22 that device also have some reading variation error. Do not expect to get 100% perfect value for 2 devices...

[nivoc]

@bjacobse Yes and no :-)

Yes 100% is outside of the spec.

And no. 33% with Magnesium Chloride Hexahydrate is inside the spec and I get 40% instead of 33-34%.

Max off should be 3% above or? Means 37% - but fair enough. Should be ok for household use.

[mvader]

@nivoc said:

@bjacobse Yes and no :-)

Yes 100% is outside of the spec.

And no. 33% with Magnesium Chloride Hexahydrate is inside the spec and I get 40% instead of 33-34%.

Max off should be 3% above or? Means 37% - but fair enough. Should be ok for household use.

I hope the Temp measurements are not off by that much.
i don't need .00001 accuracy or anything. but i feel a big difference between 70 and 72 in my house.

[bjacobse]

@mvader
Spec is: High Accuracy Temperature Sensor ±0.4 °C (max), –10 to 85 °C
So the temp accuracy is quite good

[bjacobse]

@nivoc
Yes you are right, +-3 from your humidity solution on 33%, then the reading could be in the interval 33-3=30% or up to 33+3=36% and should not show 40%

did you get same false readings from other sensebender humidity sensors?

[nivoc]

@bjacobse Yes I have 3 sensbener running from 2 different orders. All 3 are very near by each other. So at 33% they all read something near to 40%.

I have 4 more sensbenders to build. However I continue to test tonight with a Boveda-Pack that claims to bring the hum in a containter to exactly 69%. I did 4 test's so far and also used different technics. So i get more and more confident.

But the very good thing is - it looks every reproducible. So the value may be off but reproducable accurate off by about 8%. When I completed my test it will be very easy to correct it within the software.

[nivoc]

@mvader I haven't made any very accurate temp testings. But the readings are exactly the same than other non-sensbender devices in my home. I started researching the humidity b/c I had different readings between different devices.

Temp looks fine to me.

[tcontrada]

What is the current consumption of the Sensebender during sleep and active modes?

Thanks,
Tony

[tbowmo]

@tcontrada

there are some measurements in the old design thread here http://forum.mysensors.org/topic/510/minimal-design-thoughts

[nikos1671]

Hi. What case you all using for the sensebender ?Any good idea.

[filipq]

[tbowmo]

@filipq

Where did you find that box?

[filipq]

@tbowmo

Got it from http://cpc.farnell.com/1/1/57932-evatron-pp42m-case-sensor-ivory-71x71x27mm.html.
Not the cheapest, but definitely worth the money as it is very good quality. There are other colours available (white and black) https://www.jprelec.co.uk/store.asp/c=552/Gas-Sensor-Case

[scalz]

@tbowmo: I have some of these too, it's nice box. i got these from tme. cheaper :)
http://www.tme.eu/fr/details/box-sens-white/boitiers-dappar-dalarme-et-de-capt/supertronic/

[ahmedadelhosni]

Hello @tbowmo

Doesn't the atmega328 has only 2 pins which are D2 and D3 from external interrupts ?
I am wondering why do we waste the usage of D2 since the IRQ pin is not used in the library ?

[Anticimex]

@ahmedadelhosni because it is not in use by the library <yet>. Would be a shame if the library some day gets updated with support for a radio that can enter low power sleep and still wake when needed.

[tbowmo]

@ahmedadelhosni

What @Anticimex said.. And at the time when I created the sensebender, I didn't know that the interrupt wasn't used (I was relatively new to the project) so I thought that we had to have it connected..