I have BMP180, BME280, HTU21D and SHT31 since longtime inside a Davis shield. I can say, that the Bosch sensors are surprisingly different in measuring. HTU21D and SHT31 are nearly identical. There are no other electronics than the sensors inside the Shield. What all sensors have in common: They react quite identical on changes. What also can be a problem: errors in the used arduino libraries. I prefer I2C on this sensors to omit some calculation errors.
Here you see, that the difference between the two Bosch Sensors is around 1° I think they are designed for mobile phones, where you cannot expect exact weather measurements.
Bosch sensors tend to go very quickly to 100% humidity imho
Yes, the BME280 is not made for temperature measurement (as also stated in the datasheet), for temperature I use the easy to use and easy to place DS18B20 so far. That humidity goes fast to 100% is a real pain yes @BoRRoZ. Maybe I will change it one day…
At least I need temperature, humidity and pressure, and I would like to not interact with too much different sensors…
Maybe this one would be a nice candidate to test, maybe someone has already used it?
https://www.aliexpress.com/item//32803871022.html
It is a small breakout wich holds a Si7021 and BMP280.
there is also is lesser discussed aspect of those cheap I2C sensors… some of them don’t have a ‘real’ I2c bus.
the manufactures do that to avoid license fees.
sure they work with the available libraries, a problem can occure when you put the mcu in deepsleep and then wake up, for example the older sensirion (SHT) sensors had that 'problem
@mat89 did you buy that davis shield online in the ELV shop ? … I can’t find it ( need more coffee)
this tindie UK shop is specialised in sensors (and very helpfull to)
edge connectors- for outdoors use the longer ones So you can mount an O-ring
sorry @BoRRoZ, I’ve missunderstand your question, you mean where I got my Davis shield from, not the cheap shields .
I got it from Switzerland from this shop: http://www.meteo-shop.ch/7714?keyword=7714&category_id=0
OK, thank you for the input about the SHT sensors and also the link to tindie. Maybe I should simply try the one from ali and test if it does work or not.
Indeed, but I don’t regret it as after a first session of use I really appreciate it.
Associated with a pico projector, nice for group work.
and I’m still waiting… … looks great and good to hear that your happy with it.
did you bought that one lens to increase the workspace separate ?
Yes I bought it. It is a little bit too effective, I have to set the base of the gantry all the way to the top of the steel tube to get a focusable view.
But it actually leave a lot of room for soldering which is good.
If something like a x0.75 one exists it would probably be enough.
Also see:
- Redirecting...
Note: Somewhere he writes “It’s a bit hard to read the legend. The red points are the BME280 data, the olive points are the DHT22 data, the blue points are the HTU21D-F data, green points are the SHT31-D data, and, finally, the purple points are the Si7021 data.”
But that is incorrect (he apparantly has difficulty reading the legend colors himself): Blue is the SHT31-D and green is the HTU21D-F. - Testing and Comparing Low Cost Hygrometers
- Compare DHT22, AM2302, AM2320, AM2321, SHT71, HTU21D, Si7021, BME280
- Compare DHT22, AM2302, SHT31, SHT71, Si7021, BME280.
- DHT22 / AM2302 / DHT11 / SHT71 : How fast?
DIY StevensonScreen made from 'upside down plastic bowls
absoluyely nottoscale model LoRa tracker antenna BoRRoZ™
basically its a 50% rotating reflector around a stationairy 3 dbi antenna
the reflector only comes out when the signal is getting weaker, direction is controlled by gps
real tube dia = ca 34 cm … not tested yet but found the parts so I’m gonna build it… someday
theoretically it could work
FRAM … connecting it was the easy part
I’ve asked the manufacturer for more info … can it be 'hacked for EU use ? ( $88.69)
update : I translated the chinese datasheet and basically they have 2 types, wifi / gsm both connect to a private network… lorawan A,C @ 433mhz , my guess… forget it
for further info : Shenzhen Moron Technology Co., Ltd
when storing sensordata in FRAM you need to timestamp it … so an onboard RTC.
there are these DS3231 mini pcb’s… if you remove the header they are pretty small.
mini RTC DS3231
test I2c bus again
set the RTC time with help from the excellent J.Christensen library
A lot of construcion work done this sunday afternoon: 2 gateways! one IMST and one RK831. now lets look for a nice housing.
Please no PVC thats no good for RF. Sorry.