Bmp280 and Bme280

[dr pepper]

I wanted a pressure/temp/humidity sensor for a wifi project.
Being tight I bought a Bmp280 because they were a little cheaper.
Fell into a trap, the Bmp280 doesnt measure humidity, just temp & pressure, the Bme measures all 3.
If you come here as a result of a google search beware of this.
Oh and the default address is sposed to be 0x77, for my module its the alternative 0x76, it must be linked internally.

 

[Nigel Goodwin]

Thanks very much, I was looking at ordering some just the other day - but in the end I didn't, like you I was confused by the lower price and hadn't realised the cheaper one doesn't do humidity.

As for the address, I find it's a good idea to simply run an I2C address tool and read it out

I've spent ages in the past messing around, simply because I didn't measure the address and beleived the literature.

 

[dr pepper]

Glad to be of help.
I found the address not by using a scanner, I found an example program that looks for all the addresses the chips are capable of inhabiting.
Despite the fact it doesnt do humidity the accuracy is still pretty good.
I'm still going to be ordering the correct ones though.
Edit: Interestingly the sparkfun Bme280 driver works with this Bmp280, once you change the address using mySensor.setI2CAddress(0x76), just that the humidity reads 0.

 

[DrG]

In my case, I bought what was clearly advertised as a BME280 and explicitly stated temperature, pressure and humidity.

Here is the board:

Close up of the component:

That 'KS' identifies the chip as a BMP280 and not a BME280 (see here for links and discussion - I'm not even saying it is a genuine Bosch chip). It gives the sensor ID as 0x58, also identifying it as a BMP280. I went through a similar sequence with software as Pommie Dr Pepper and then did some reading that I should have done before clicking "buy". In my defense, it was only US$1.08, including shipping.

I just bought another one. This one was only US$0.99 with shipping but it has the correct 'UP' marking on the chip in the advert. I'll let you know in a couple of months when it arrives.

 

[Nigel Goodwin]

In my case, I bought what was clearly advertised as a BME280 and explicitly stated temperature, pressure and humidity.

I just bought another one. This one was only US$0.99 with shipping but it has the correct 'UP' marking on the chip in the advert. I'll let you know in a couple of months when it arrives.

Be interesting to hear what arrives - although you can't go by what's printed on components, as they commonly remove the markings and relabel them.

 

[DrG]

Be interesting to hear what arrives - although you can't go by what's printed on components, as they commonly remove the markings and relabel them.

RE: relabel, fake label, fake chip and so on.....Yes!

In this case, what I could have gone on, what I should have gone on, was several review comments stating that it was not a BME but a BMP, but I didn't read them at the time of purchase. Even though there were several other comments saying, "yes, it is a BME", it should have been enough to convince me to steer clear. In this case, I was just being carefree...with $1.

The new purchase has over 100 sales and no reviews saying it is a BMP...I am optimistic, but by the time it arrives, I may have forgotten all of this and will wonder..."now why did I buy this?"

 

[Nigel Goodwin]

RE: relabel, fake label, fake chip and so on.....Yes!

Well as long as you identify it as fake pretty quickly, get back in touch and get your money back - I've had no problems getting refunds from China for broken or faulty goods. The fake DS18B20's I had unfortunately got stuck in a draw, and by the time I got round to using one it was far too late to do anything, and I couldn't even remember where they had cone from

 

[dr pepper]

I just checked the listing again for mine, it does say Bmp280 not Bme, however the listing clearly states that it does humidity, even states the accuracy.
The seller probably doesnt even know what they are selling.
I've had fake parts before, very annoying.

 

[DrG]

Be interesting to hear what arrives - .

The two that I ordered arrived yesterday. Despite the advert that clearly mentioned both BME and humidity, what I received were BMP280s. The total cost for the two (no shipping charge) was US$1.96. I explained that they were not BME280s as advertised and I received a refund of US$1.96. No request to return them and no communication at all from the seller - just the refund.

Undaunted by the missteps and determined to get an actual BME280 (or clone), I ordered from another vendor. This time it is a US seller and the advert, again, clearly mentions BME280 and humidity. I decided that the compulsion demanded an increase in investment and I ordered a single one at US$4.94. It should arrive in the next 10 days and I am anxious to see what I get.

I add two points:
1) A BMP280 for US$1 is dirt cheap - why wouldn't they simply advertise it as such (don't answer that, it is rhetorical).
2) I need another humidity sensor like I need hemorrhoids, but it is the principle - which is apparently, "I want one".

 

[dr pepper]

Check the accuracy of the bmp's temperature reading, mines way off.

 

[DrG]

Check the accuracy of the bmp's temperature reading, mines way off.

I only casually looked at their accuracy and they all *looked* reasonable. I need to get one very good temperature measuring device and just use that as a standard - it is something of a short cut but reasonable for most of what I am interested.

BTW: I have been working on a BLE data logger and the sensor bank (a TI SensorTag) has multiple temperature sensors, including a BMP280. Here is what a correlation between the two looks like over a relatively small range.

Clearly the measures are close to each other with about a 1.0 degree bias - of course that means little alone. I would not mind having something like this handy.

BTW: Still waiting on my "BME280" which was supposed to arrive here on two days ago - USPS 1st class.

 

[dr pepper]

Nope mines 6 degrees celcius different.
I have access to a calibrated 0.1 degree c temp gauge.

 

[DrG]

The BME280 cam in....and it works!

Temperature = 26.76 *C
Pressure = 1006.60 hPa
Approx. Altitude = 55.52 m
Humidity = 50.40 %

 

[dr pepper]

Excellent, can you send me a link to the seller I'll get a couple.

 

[DrG]

Excellent, can you send me a link to the seller I'll get a couple.

Yeah, I believe I got it here https://www.ebay.com/itm/BME280-Temperature-Humidity-Barometric-Pressure-Digital-Sensor-Module-Arduino/202678765887?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649

I think you already know this, but I feel like I should write it anyways...I have nothing to do with that seller and have no idea how good or bad they are - in this case, however, I am happy with the purchase.

Here is the board:

Looking closely at the BME280E, you can see the markings 109 and UP.

Looking again at this site, which I mentioned previously, that UP marking is the only one to indicate a BME while there are many others signifying a BMP. That has now been my experience as well.

For the heck of it, I put a DS18B20 right next to this BME280 and ran some comparison temperature reads (see below - those are 30 second intervals).

BME    DS1820  Diff
24.64  23.62   1.01
25.00  24.19   0.81
25.11  24.37   0.74
25.20  24.50   0.70
25.20  24.62   0.58
25.24  24.69   0.55
25.30  24.75   0.55
25.37  24.81   0.56
25.41  24.87   0.53
25.43  24.94   0.49
25.46  25.00   0.46
25.48  25.00   0.48
25.50  25.06   0.44
25.52  25.06   0.46
25.53  25.12   0.41
25.55  25.12   0.42
25.59  25.19   0.40
25.61  25.19   0.42
25.63  25.25   0.38
25.62  25.25   0.37
25.66  25.31   0.35
25.67  25.31   0.36
25.68  25.31   0.37
25.71  25.31   0.40
25.73  25.37   0.35
25.76  25.44   0.32
25.77  25.44   0.33
25.79  25.44   0.35
25.80  25.44   0.36
25.82  25.50   0.32
25.85  25.50   0.35
25.85  25.56   0.29
25.86  25.56   0.30
25.86  25.56   0.30
25.87  25.56   0.31
25.86  25.56   0.30
25.86  25.56   0.30
25.83  25.56   0.27
25.85  25.56   0.29
25.87  25.56   0.31
25.87  25.56   0.31
25.85  25.56   0.29
25.86  25.56   0.30
25.86  25.56   0.30
25.88  25.56   0.32
25.89  25.56   0.33
25.88  25.56   0.32
25.88  25.56   0.32
25.86  25.56   0.30
25.86  25.56   0.30
25.84  25.62   0.22
25.82  25.62   0.19
25.83  25.62   0.20
25.81  25.62   0.18
25.75  25.62   0.12
25.78  25.56   0.22
25.77  25.56   0.21
25.81  25.56   0.25
25.77  25.56   0.21
25.76  25.56   0.20
25.74  25.56   0.18
25.70  25.56   0.14
25.70  25.56   0.14
25.70  25.56   0.14
25.70  25.56   0.14
25.70  25.56   0.14
25.75  25.56   0.19
25.73  25.62   0.10
25.72  25.62   0.09
25.74  25.62   0.11
25.74  25.62   0.11
25.74  25.62   0.11
25.75  25.62   0.12
25.74  25.62   0.11
25.71  25.62   0.08
25.74  25.62   0.11
25.76  25.62   0.14
25.77  25.62   0.15
25.74  25.62   0.11
25.72  25.62   0.09
25.71  25.56   0.15
25.74  25.56   0.18
25.75  25.62   0.12
25.82  25.62   0.19
25.87  25.62   0.25
25.92  25.69   0.23
25.97  25.69   0.28
25.99  25.75   0.24
25.96  25.75   0.21
26.00  25.75   0.25
25.99  25.75   0.24
25.96  25.75   0.21
25.98  25.75   0.23
25.97  25.75   0.22
25.99  25.75   0.24
25.97  25.81   0.16
25.95  25.81   0.14
26.00  25.75   0.25
26.01  25.75   0.26
25.98  25.75   0.23
26.00  25.75   0.25
25.98  25.75   0.23
25.99  25.75   0.24
26.01  25.81   0.20
26.01  25.75   0.26
26.02  25.81   0.21
26.01  25.81   0.20
26.02  25.81   0.21
25.98  25.81   0.17
26.02  25.87   0.15

After some "settling", the two sensors produce very similar values.

 

[dr pepper]

No responsibilty assumed.
Mute point anyway I'm in the Uk and the seller doesnt ship here.
I sent them a Pm just in case they do and its not really expensive, I heard shipping rates over there are silly.

 

[DrG]

Decided to evaluate the humidity sensor on the BME280 (using NaCl, MgCl, LiCl and KCl) . It could have been much better as I observed up to a +/-5.5% error (calculated an average error of 8.86%), but calibration in software is easy enough to do and seems reasonable in this case.

 

[dr pepper]

At least its linear and repeatable.