BME280 not working

[oetaelse]

I have a BME280 sensor (temp, pres and hum) connected to an Node MCU board with build 120.
The device is found on the i2c bus as 0x77 BMP085/MS5607/MS5611 howevever no data is shown in the web interface.
I noticed that this is a different BME model as show in the supported hardware page, i have a model from adafruit.
The device is working properly if it's connected to an Arduino UNO.
Is there a way to get this device working?

Thx, Rob

[Drum]

I have one (adafruit module) on an esp12 and it works fine. What is it not doing? How is it connected? Any resisters between SDA/SCL and 3.3v?

[oetaelse]

Hi Drum, there's no data shown in the web interface.

VIN is connected to 3.3V
GND is connected to ground
SCK is connected to D1
SDI is connected to D2

There are no resistors used.

I have a GY-30 Luxmeter connected to the MCU on the same ports (D1 and D2), this device is working fine.

[oetaelse]

Got it fixed, connected SDO to Ground, this changes the I2C address from 0x77 to 0x76.
Now it's recognized as BME280/BMP280/MS5607/MS5611.
Furthermore I connected CS to VCO, this will add more stability and disables SPI.

[Drum]

I set up a new one over the weekend and when I look at the old one I saw I also had that connection. I Expect I had the same problem and also had to connect SD0 to Ground, just did not remember why.

[nightshark]

Mine was working fine for 2 days. Now this morning it's showing up as the BMP085. I'll try the SDO/ground option later today.

Thanks for the info!

[NDR008]

I have one LoLin nodeMCU running BMP-280 without problems.
I have a second Amica nodeMCU running another BMP-280 with problems (the value is correct, and occasionally goes completely crazy - like -137.5degC and 1254.80mbar.

What could be the issue with the second one?

[TD-er]

What version of ESPeasy are you running?
I changed a lot for the Bosch sensors in the Mega branch.

[NDR008]

On the working node - not sure.
(It says custom but I think I compiled dev12)

On the glitchy one - the very latest 2018 build.
mega-20180104

Could it be the floating sdo?

[grovkillen]

On the working node - not sure.
(It says custom but I think I compiled dev12)

On the glitchy one - the very latest 2018 build.
mega-20180104

Many mega releases has been published after your version.

https://github.com/letscontrolit/ESPEasy/releases

[NDR008]

GIT version: mega-20180117
Also not working well.

Could it be the floating sdo?

[NDR008]

I will try to wire it better tonight to eliminate weak connection.

I am now using Dupont header like wires

[TD-er]

Hmm the I2C address in your start post just triggered something here.

Taken from the datasheet:

The 7-bit device address is 111011x. The 6 MSB bits are fixed. The last bit is changeable by
SDO value and can be changed during operation. Connecting SDO to GND results in slave
address 1110110 (0x76); connection it to VDDIO results in slave address 1110111 (0x77), which
is the same as BMP280’s I²C address. The SDO pin cannot be left floating; if left floating, the
I²C address will be undefined.

With the Mega branch and BMx280 as plugin, you should see an immediate update (after save) next to the address selection indicating the detected device.
For example on my setup: [Detected: BME280]

So please have a look at the SDO pin and it may also help to add 10k pull-up resistors between SDA and Vcc (3.3V) and also one for the SCL line.

[NDR008]

It looks like the SDO might have been the culprit.
Which is weird - my other BMP280 had no issues except that I connected it on a breadboard so maybe somehow to metal contact on the breadboard helps? Or manufacturing tolerance?
Anyway, I ground SDO, and am so far having no abnormal readings so far.

[NDR008]

Is it me, or the polarity of the 2 i2c lines seem to not matter?

[TD-er]

Is it me, or the polarity of the 2 i2c lines seem to not matter?

What do you mean? Switching SCL and SDA? or signal level polarity?
That last one seems quite odd, since you'll have to do some very strange wiring to do that.

[NDR008]

Switching SCL and SCD

[TD-er]

Switching SCL and SCD

Maybe the Bosch sensor has some intelligence to do that.
But it's not standard behavior.