Author Topic: Sensirion SHT85: New Humidity & Temperature Sensor Replacement  (Read 1285 times)

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Online galfert

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Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« on: October 22, 2018, 08:41:38 PM »
Looks like the new Sensirion SHT85 humidity and temperature sensor will soon be available. Both Mouser and Digikey have it listed and you can pre-order. Mouser says availability is December 3rd and Digikey is saying November 14th.

From the spec sheet it looks like this will replace the SHT75 as their flagship product. The SHT75 was starting to become dated where in some respects the SHT35 was better. Good timing from Sensirion on coming out with the SHT85.

This new sensor will only be I2C compatible. Which means current Davis stations will not be able to use it. Although some work is being done by rdsman on this forum to try and convert I2C to sensibus via clever technique of drop and insert into the sensibus signal using both an old a new type sensors simultaneously.

It is possible that some newer devices like Ambient Weather WS-2000 or WS-2902A and also Acurite with the Atlas line, that they could get hacked and replace the existing SHT3x in those devices for the SHT85. These new devices are most likely using the new I2C protocol versions of the  SHT3x and should make replacement with the SHT85 straight forward. Of course there might be mounting or soldering hacking involved. Ambient is using the SHT30 and Acurite is using the SHT31.

Really would be nice to see Davis finally release a VP3 that uses the I2C protocol with a brand new SHT85 to rule the roost. Unless Davis has hoarded up sufficient amounts of old discontinued stock of SHT31 sensors with the old legacy LSS protocol, they will need to come out with a new VP3 soon. Let's hope that they update their display consoles too while they are at it.

Is anyone planning on experimenting with the SHT85 sensor? Price of this new sensor is around $30.

UPDATE: Back when I wrote this not enough was known about the new up and coming SHT85. Now we know that the SHT85 is nothing but a board mounted SHT35. Same sensor chip.
« Last Edit: July 07, 2020, 08:29:45 AM by galfert »
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Offline HansR

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #1 on: July 07, 2020, 02:40:26 AM »
Thanks for the post.
I was looking for compatibility of SHT85 with the 75 or the 35. Clear answer here.
Davis did not come up yet with a VP3 though ;)

Offline mcrossley

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #2 on: July 07, 2020, 06:03:18 AM »
Afaik the SHT85 is just a board-mounted SHT35, just like the SHT75 was a board-mounted SHT15.

A more convenient package for us to play with, but not a new sensor.
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Offline HansR

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #3 on: July 07, 2020, 07:32:38 AM »
Afaik the SHT85 is just a board-mounted SHT35, just like the SHT75 was a board-mounted SHT15.

A more convenient package for us to play with, but not a new sensor.
Interesting because Galfert says:
This new sensor will only be I2C compatible. Which means current Davis stations will not be able to use it. Although some work is being done by rdsman on this forum to try and convert I2C to sensibus via clever technique of drop and insert into the sensibus signal using both an old a new type sensors simultaneously.

It is exactly the board mounted, protective sheet covered, which drew me to this and I started searching. From what I found I think Mark is right, but now not so sure.
So, who's right  :???: ;)
Anybody tried to proof the pudding?

Offline johnd

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #4 on: July 07, 2020, 07:40:40 AM »
There's no contradiction AIUI. Some members of the SHT series such as SHT31 (but not SHT35 AFAIK) are produced with (at least) two different interfaces - the so-called Sensibus which is an older protocol and the one that Davis use and 'full' I2C. The two interfaces are related but are incompatible. So a non-Sensibus but I2C SHT35 could not talk to a VP2 SIM board.

That's my understanding at least.
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Offline HansR

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #5 on: July 07, 2020, 08:24:42 AM »
There's no contradiction AIUI. Some members of the SHT series such as SHT31 (but not SHT35 AFAIK) are produced with (at least) two different interfaces - the so-called Sensibus which is an older protocol and the one that Davis use and 'full' I2C. The two interfaces are related but are incompatible. So a non-Sensibus but I2C SHT35 could not talk to a VP2 SIM board.

That's my understanding at least.
But the question is: can the SHT85 talk sensibus (so can be used as a replacement in the Davis) or not.
Galfert says : No
mcrossley says: Yes

Pardon me, but I see that as a contradiction.

Online galfert

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #6 on: July 07, 2020, 08:31:12 AM »
Back when I wrote this in 2018 about the SHT85 coming out, not enough was known about the new up and coming SHT85. But since it's release and specs we know that the SHT85 is nothing but a board mounted SHT35. Same sensor chip. Like the SHT35, the SHT85 is only available in I2C version. No Sensibus.
« Last Edit: July 07, 2020, 08:38:29 AM by galfert »
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Online galfert

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Re: Sensirion SHT85: New Humidity & Temperature Sensor Replacement
« Reply #7 on: July 07, 2020, 08:33:59 AM »
There's no contradiction AIUI. Some members of the SHT series such as SHT31 (but not SHT35 AFAIK) are produced with (at least) two different interfaces - the so-called Sensibus which is an older protocol and the one that Davis use and 'full' I2C. The two interfaces are related but are incompatible. So a non-Sensibus but I2C SHT35 could not talk to a VP2 SIM board.

That's my understanding at least.
But the question is: can the SHT85 talk sensibus (so can be used as a replacement in the Davis) or not.
Galfert says : No
mcrossley says: Yes

Pardon me, but I see that as a contradiction.

I never said the SHT85/SHT35 would support Sensibus. I said that there was a forum member working on a project that would cleverly replace Sensibus data with I2C data by using both chips at the same time.

Mcrossley did not say it would talk Sensibus either. He said that the package difference was single chip versus mounted chip. This comment had nothing to do with the supported protocol.

Everyone is in agreement.
« Last Edit: July 07, 2020, 08:40:22 AM by galfert »
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