Wipy 2.0 and BME280 sensor



  • Hello!

    Was anybody able to use I2C BME280 sensor? It works flawlessly on Wipy 1.0 using a driver from Paul Cunnane (https://bitbucket.org/oscarBravo/wipy_bme280), but I get strange errors on Wipy 2.0:

    >>> from machine import I2C
    >>> import bme280
    >>> i2c = I2C(0, I2C.MASTER, baudrate=100000)
    >>> bme = bme280.BME280(i2c=i2c)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/flash/lib/bme280.py", line 186, in __init__
      File "/flash/lib/bme280.py", line 106, in write8
    TypeError: object with buffer protocol required
    

    It looks like this operation fails:
    i2c.writeto_mem(0x76, 0xF4, 0x3F)

    I can see the device on I2C bus, so the wiring should be OK. I also have a HD44780 display with PCF8574 backpack connected to I2C bus and it works.

    I am using the latest firmware 0.9.4b1.

    One last thing - I am connected to Wipy via telnet (Putty) and the REPL is almost unusable. After few lines of code it hangs or key presses start to generate weird characters.

    Michal



  • @Jiemde

    Hi, It works with my Wipy 2.0, i think the only change i made was:

    def write8(self, register, value):
    """Write an 8-bit value to the specified register."""
    value = value & 0xFF
    self._i2c.writeto_mem(self._address, register, bytes([value]))


  • Pybytes Beta

    Hi michal,

    Also try to use the bme280 sensor ( working with the wipy1 ok! ) but have the same errors with the wipy 2!
    Had you resolve this ? If yes could you tell me how ?

    Best regards

    Jiemde



  • @Baruch1966
    Hi!

    Here is the repository with driver from Dave Hylands:
    https://github.com/dhylands/python_lcd

    Here is the sample code:

    from machine import I2C
    from i2c_lcd import I2cLcd
    
    i2c = I2C(0, I2C.MASTER, baudrate=100000)
    lcd = I2cLcd(i2c, 0x27, 4, 20)
    lcd.putstr("It Works!")
    

    I use this display: http://www.santy.cz/zobrazovace-c7/lcd-2004-blue-i2c-i9/
    and this level converter: http://www.santy.cz/moduly-omezovacu-a-prevodniku-c34/i2c-uart-level-konvertor-3v-5v-4way-i223/

    Michal



  • @michal said in Wipy 2.0 and BME280 sensor:

    I can see the device on I2C bus, so the wiring should be OK. I also have a HD44780 display with PCF8574 backpack connected to I2C bus and it works.
    I am using the latest firmware 0.9.4b1.

    Can you share a example code with PCF8574?


  • administrators

    Hi Michal,

    Thanks for the quick feedback, glad that it works now :-)

    I got confused with I2C Quick Reference (https://docs.pycom.io/wipy2/2wipy/quickref.html#i2c-bus) which is the same for both versions of Wipy.

    It's our fault, we need to make the API accept an integer as well. Will be fixed shortly.

    Cheers,
    Daniel



  • Hi Daniel!

    I can confirm, that it works with bytes object:-)

    >>> from machine import I2C
    >>> import bme280
    >>> i2c = I2C(0, I2C.MASTER, baudrate=100000)
    >>> bme = bme280.BME280(i2c=i2c)
    >>> print(bme.temperature, bme.pressure, bme.humidity)
    24.07C 967.63hPa 64.16%
    

    I got confused with I2C Quick Reference (https://docs.pycom.io/wipy2/2wipy/quickref.html#i2c-bus) which is the same for both versions of Wipy.

    Thanks a lot for your help!

    Michal


  • administrators

    @michal when you do the i2c.scan() are you able to see the sensor connected?

    TypeError: object with buffer protocol required

    This error occurs because the function expects a bytes object and you are trying to send an integer. Could you try with:

    i2c.writeto_mem(0x76, 0xF4, bytes([0x3F]))
    

    ?

    Obviously we should make the drivers fully compatible with the old ones. We'll definitely fix it, but please try the workaround above to confirm the problem. Thanks.

    Cheers,
    Daniel


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