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Bosch Sensortec BMP280 vs BME280 Sensor Confusion
#11
Hi,

Thanks.  Yes that's exactly the seller I found on ebay.com (I guess the price is US$ not NZ$), but with free ("Economy") shipping.    Wink

Cheers,  Alan.
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#12
(14-01-2019, 02:38)AllyCat Wrote: AFAIK the SHT3x humidity sensors are 2.4 - 5.5 volts tolerant so shouldn't need any level shifter?  Wink

Yes, that is true, they are 5V tolerant, but those ones without the level shifter (the two FETs) can't be connected to the extended I2C bus on the TX interface.
Without a second I2C bus extender chip on the sensor side, they will work too, but not for so long. The reason is related to the current demanded by the I2C extended bus chip on the TX board, the SHT31 can only drive 5mA. The modules that have the two FETs, do an excellent job here as they isolate the SHT31 chip from the I2C extended bus.
Hope my poor English makes this understandable.

The info above comes from a research and experiments done by t3gathome
MeteoCercal - Air Quality Data
Click here to watch at my ThingSpeak channel



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#13
This link supplied a BME280;

https://www.ebay.co.uk/itm/192783393464?...2783393464

and I now have this Closed Cube SHT31 outside which comes complete with filtercap,

https://www.ebay.co.uk/itm/ClosedCube-SH...2974536376

These cheaper SHT31 seem to have rather more limited life though they are fine while they work;

https://www.ebay.co.uk/itm/New-SHT31-SHT...1958217394?
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