BMP280 i2c Nightmare !

Hi,

Has anyone had any luck with the cheap bmp280 modules off Ebay, I could not get my first 6 pin versions to work so I sent for a 4 pin version, I have tried all sorts to get these working via i2c, the first lot did not show up on an i2c scannerbut the second lot with 4 pins show up as 0x76 but I don't seem to be able to talk to them, tried pull up resisters and different sketches, any ideas welcome

thanks
in advance
Stuart

On eBay, fakes are common. You don't even get what you pay for.

Are you using 3.3V or 5V Arduino? In case of the latter you must have level shifters (some breakout boards have this included).

Hi vmarle,

I am using 3.3 volts, however after your suggestion I popped a couple of mosfets on the i2c line out and now it is talking and giving me pressure, Altitude and Temperature, no Humidity but I am not sure if these devices give it, I will try all my other ones now and see if I can get them working, thanks for your input much appreciated.

Stuart

Hi,

I have found this webpage which shows a picture of my 6 pin purple BME/BMP280's that I purchased from Ebay, so I downloaded and installed the libraries for i2c and spi, however the 2 sketches will not compile as certain items are not declared, if anyone can have a look and maybe shed some light on this that would be great.

Thanks
Stuart

I recommend you try the BMP280 drivers and web tutorials on Adafruit or SparkFun web sites. They both sell similar modules and the eBay modules from China also work with their drivers and example sketches. Since the eBay modules may have the I2C address wired differently, you may only need to change the I2C address in the code (when initializing the library in the sketch). SPI sketches will work as is.

Hi Borland,

Yes I know the i2c addresses of the purple units 0x76 sdo low & 0x77 sdo high, I have made sure that tjhe sketches I used set the i2c address, I think I have found the correct libraries and sketches above but they will not compile, so I am just going to see if anyone (Arduino Expert) will be kind enough to take a look and see if they can shed any light on it.

thanks
Stuart

Just tie the SDO pins via a resistor to +3.3 resp GND and you have the addresses set, much easier. Then try to use the test sketches to read your sensors, remember to change the I2C address in the sketch.