BME280 on the LoPy

[ledbelly2142]

I am trying to use the same library with a BME280 and am experienceing the exact same issue with firmware version 1.7.4.b1
same error:

Traceback (most recent call last):                                                                                      
  File "main.py", line 9, in <module>                                                                                   
  File "bme280.py", line 198, in init                                                                               
  File "bme280.py", line 204, in _load_calibration                                                                      
  File "bme280.py", line 164, in readU16LE                                                                              
  File "bme280.py", line 147, in readU16  

Did anyone get this to work?

[Butch]

@ledbelly2142 said in BME280 on the LoPy:

I am trying to use the same library with a BME280 and am experienceing the exact same issue with firmware version 1.7.4.b1
same error:

Traceback (most recent call last):                                                                                      
  File "main.py", line 9, in <module>                                                                                   
  File "bme280.py", line 198, in init                                                                               
  File "bme280.py", line 204, in _load_calibration                                                                      
  File "bme280.py", line 164, in readU16LE                                                                              
  File "bme280.py", line 147, in readU16  

Did anyone get this to work?

Try my fork of the library: https://github.com/ButchAnton/LoPy_BME280

[ledbelly2142]

@Butch
yup, thats what I'm using. I forked it. Why the init.py file?

[Butch]

@ledbelly2142 That makes it into a package: https://docs.python.org/2/tutorial/modules.html#packages

[ledbelly2142]

@Butch
I still have the same issue, just updated to the latest firmware 1.7.5.b2
In the main.py I'm just trying to print out values in the console, I have:

import pycom
from machine import I2C
import time
import bme280 # from bme280

i2c = I2C(0, I2C.MASTER, baudrate=100000)
i2c.scan()
#i2c = machine.I2C(0, pins=('GP11', 'GP10'))
bme = bme280.BME280(i2c=i2c)

pycom.heartbeat(False)

temp = BME280.temperature()
humid = BME280.humidity()
press = BME280.pressure()
alti = BME280.altitude()

#for cycles in range(10): # stop after 10 cycles
while(true):
    print(temp) # read temperature
    time.sleep(2)
    print(humid) # read humidity
    time.sleep(2)
    print(press) # read Pressure
    time.sleep(2)
    print(alti) # read altitude
    time.sleep(2)

[Butch]

@ledbelly2142 Try following the line of logic I tried in the python REPL: import, instantiate, and initialize:

>>> from machine import I2C
>>> import bme280
>>> i2c = I2C(0, I2C.MASTER, baudrate=100000)
>>> bme = bme280.BME280(i2c=i2c)

See where that takes you.

The original problem I ran into and ultimate fixed was that the 8- and 16-bit writes needed the value to be written to be a bytearray, not the raw value. Beyond that, all I added was a wrapper for altitude.

[ledbelly2142]

@Butch

For me, the issue comes up from :
bme = bme280.BME280(i2c=i2c)

Thats where I get the errors indicating an I2C bus error.

I SDA on pin 9 and SCL on pin 10.

Could it be a bad sensor?

So I unplugged the BME280 sensor and got the same error.

[Butch]

@ledbelly2142 It's possible that it's a bad sensor. Do you have another one to try? You might also check to make sure that i2c.scan() is returning the same address that is used in the BME280 library. If it isn't, you'll have to change the address in the library.

[ledbelly2142]

@Butch
That looks to be it. The I2C address was 77, not 76... weird. I did not think to check the I2C address.

Thanks!

[Devang Sharma]

Hello Everyone,
I'm using LoPy and I've got the similar type of error as @binux got.

I'm getting the following error:

This is my code:

Please guide me solving this!
Thank You.

[robert-hh]

@devang-sharma The required positional argument is 'little' in the call of from_bytes(). The API was changed a while ago. You have to modify the script BM280.py into:

        result = int.from_bytes(
            self._i2c.readfrom_mem(self._address, register, 2), little) & 0xFFFF

The same in function readU8().

[Devang Sharma]

@robert-hh I've done changes as you said but got the NameError as:

"name 'little' is not defined". How can I solve it?
Thank You.

[robert-hh]

@devang-sharma Sorry, it should be a string:

        result = int.from_bytes(
            self._i2c.readfrom_mem(self._address, register, 2), 'little') & 0xFFFF

[Devang Sharma]

@robert-hh, that worked! Thanks, but the same error for write8:

Is there any link to the changed API or library? That would be better than posting every single error! :'D

EDIT: Solved the error. Replaced value.to_bytes(1) with "value"! No more Errors!

[robert-hh]

@devang-sharma No specific API doc needed, since it is standard Python behaviour now. It was incompatible before, but I'm not shure, for which MicroPython version. It may be that the Pycom branch always was compatible to the Standard.
And yes, even in that case changes toward language compliance may break code, so it should be noted.

[robd]

Hello,
There are quite a few entries on the BME280.
I have been reading them and I am still not able to fix my issues.
I have tried several of the libraries and I am just at a stand still.
When I do a scan of the I2C port I get 0x76 so I know that the sensor is there.
What I get is as follows (firmware rev 1.10.2.b1)

Thank you,

[robert-hh]

@robd Actually, which bme280 code are you using at the moment? I'm a little bit lost too.

[Devang Sharma]

@robd I've faced a similar issue and added argument 'little' as @robert-hh suggested which worked for me. I don't know which library you're using. But I've been using this:

https://github.com/LoRaWeather/BME280-LoPy-TTN/tree/master/Program/lib

[seb]

This post is deleted!

[robd]

@devang-sharma thank you for the link. I really hate learning curves. I tried the TTN libraries and I still have issues. How are you calling the library?
I am trying with (firmware version 1.10.2.b1)

from machine import I2C
import BME280
i2c = I2C(0,I2C.MASTER, baudrate=100000)
bme = bme280.BM280(i2c=i2c)

print('Temp = ', bme280.temperate())

the errors I am getting are

I then tried to see if my sensor was readable and I did

from machine import I2C
i2c = I2C(0, I2C.MASTER, baudrate=100000)
i2c.scan()

which returned 118 (0x76)
then I did the following

Any pointers to my errors?

Thank you