Prop object for Sensirion sht20, sht21, sht25 series
Tracy Allen
Posts: 6,656
I don't think I'd ever uploaded this. Did a bit more work on it over the weekend, demo+object. This object uses genuine i2c, so it can sit on a standard i2c buss.
-- sht2x is much cheaper than the sht1x or sht7x! I'm using it exclusively, except for projects that need the special geometry of the sht7x.
-- only one device address available, $40 7-bit ($80 8-bit). Kind of a bummer to allow only one on a buss.
-- 3.6V maximum Vdd
-- can also respond to the SHT11 protocol (like i2c but non-conforming).
This object uses conforming i2c and has options for either the clock-hold mechanism or the trigger and wait/poll mechanism. Demos both mechanisms. There is an option for the resolution vs speed tradeoff.
The math to go from the raw reading to °C and %RH differs from the SHT1x. There is no longer temperature compensation of RH required at least to first order.
There is also an sht3x series in the works, not yet in distribution AFAIK. Smaller with wider voltage range and again slightly different protocol, but at least it offers two addresses.
-- sht2x is much cheaper than the sht1x or sht7x! I'm using it exclusively, except for projects that need the special geometry of the sht7x.
-- only one device address available, $40 7-bit ($80 8-bit). Kind of a bummer to allow only one on a buss.
-- 3.6V maximum Vdd
-- can also respond to the SHT11 protocol (like i2c but non-conforming).
This object uses conforming i2c and has options for either the clock-hold mechanism or the trigger and wait/poll mechanism. Demos both mechanisms. There is an option for the resolution vs speed tradeoff.
The math to go from the raw reading to °C and %RH differs from the SHT1x. There is no longer temperature compensation of RH required at least to first order.
There is also an sht3x series in the works, not yet in distribution AFAIK. Smaller with wider voltage range and again slightly different protocol, but at least it offers two addresses.
Comments
Attached is a picture of the breakout board I made as a quick trial of the sensor. After looking at the date I was a bit shocked. I made that in December 2009, just over 5 years ago!
Are you using the SHT21 directly on your logger boards or did you make it into a module?
You saw my pcb back in posts #24 and #26 this thread SHT-22-and-Basic-Stamp. I promised to send you some of my boards at the time and I apologize if I slipped up on that. I can try it again. I have plenty of them, multi-up strips, small circular pcbs meant for probe mounting. My current application will affix the SHT21 directly on a larger circuit board along with air quality sensors, well ventilated with a fan.