[Pytrack] Problem getting an extra I2C sensor working on different bus, pins

[Marco den Hartog]

Hi all,

I have a Pytrack and added a BME280 sensor as follows on the External IO Headers.

VCC - Pin 3
GND - Pin 1
SCL - Pin 7 (P10)
SDA - Pin 8 (P11)

My code:

i2c_env = machine.I2C(1, machine.I2C.MASTER, baudrate=400000, pins=('P11', 'P10'))

What happens is that the program hangs on this initialization. Probably I misunderstand something with initializing the I2C on a different bus and pins.

Thanks.

[Xykon]

@marco-den-hartog Have you tried adding external pull-ups on the bus.

[Marco den Hartog]

@xykon Hi. Yes I tried that and also soldering it the SDA to PIN 6 (P9) and SCL to PIN 7 (P10). I am using the WiPy 3.0 with the latest firmware. When initializing it on I2C bus 1 is hangs. When I use bus 2 then the device crashes. Now I have connected the BME280 directly to the configured PINS on the Pytrack for I2C bus 0 and everything runs smoothly.

Looks like there is something not correctly or on the Pytrack board or on the software side. My guess is on the software site because I get some voltage on the pins when using the External IO headers.

[Xykon]

@marco-den-hartog OK thanks for the update. I will investigate this further tomorrow as I do not have the necessary hardware at home.

You can also try downloading an older firmware here: https://software.pycom.io/downloads/WiPy.html

I'd suggest you try WiPy-1.17.0.b1.tar.gz first and then WiPy-1.16.0.b1.tar.gz

[Marco den Hartog]

@xykon Hi I didnt't told you but have tried 1.16.0.b1 and 1.15.0.1 with both the same results. But with some wires soldered it is working fine.

The following schema now is running:

External IO Header :
PIN 1 - GND
PIN 4 - VCC 3V3 SENSORS

Header(connected a wire underneath the board)
P22 - SDA
P21 - SCL

I have now a working demo device for this week :)