favorite I2C temp + humidity sensor

Sensirion was one of the first to offer temperature and humidity integrated circuit sensors - I ran into them around 2002.

Newark/element 14 lists some 33 of their parts, and stocks about half of those.

is the cheapest, but they have no stock - it is shipped as full reels

is twice the price but they have 169 in stock and it does ship in single units (on cut tape).

Thanks, Bill. I had a folder of their stuff in my computer, but hadn't been taking a good look at them. I like what I see.

I had the Sensirion sensors in some products. They have a somewhat modified view of the I2C/TWI protocol. Also, the sensors had a tendency of locking up without any external trigger, so we had to add a power switch FET to their feed to reset the lockup.

Ouch, I don't have that on my production PCB.

Hey, Win, what don't you like about the BME280? Just the extra cost? I designed them into a few different airborne boxes to monitor the environmental conditions. Convenient and tiny.

--Spehro Pefhany

I do like the BME280, and will still have one in my beehive monitor. But we need to spread T+H sensors around inside the hive, and it seems strange to have pressure at each spot. We'd also like redundancy.

Are there any such sensors that specify min- and max values. Specifying only typical values, as with th BME280, does not enhance my confidence in those products.

Whaddya want for dirt cheap?

The data sheet for the Sensirion SHT21 talks about a low power state and a "soft reset command" sent over the serial bus to get it going again.

You haven't specified which part you used, nor whether the "locking up" feature you observed was a bug - not mentioned in the data sheet or the supporting literature - or a feature which happened to have been ignored by the engineer that set up the system.

I've had to tidy up enough systems that were put together by slap-dash engineers working under time pressure to be aware that some people don't seem to be able to find the time to read datasheets carefully and comprehensively.

Dana subota, 13. travnja 2019. u 20:33:15 UTC+2, korisnik Winfield Hill napisao je:

Hi, I'm using TI HDC1080.

Wow, I didn't know they had one! How much experience do you have with it, are you happy with it?

SHT21 is a different beast than SHT11.

The lockup affected the analog part of the sensor, its I2C traffic was flowing well but feeding meanless values.

Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:

snip

Wow from me too... It looks like a really good device.

I am going to make an ESD strap test station module with a humidity readout.

That way, a worker noticing a low humidity can alert the manager about the unsafe electronic component atmosphere.

Anything below 35% RH is too low (I put my line at 40%). Folks dismiss it as being an issue, but I have seen the damage first hand, and damage that did not immediately present itself. ESD kills electronics circuitry and one needs not notice 'a spark' for said damage to happen.

Sounds like it'll be a useful product.

napisao

So far I used HDC1000 (old discontinued part). First I used on my table for testing and now using in my own thermostats. For me it's better and cheape r than SHT15. Now I ordered HDC1080 and redesign PCB adapter. Still waiting PCB from manu facturer.