Astrid: I debugged an I2C bus just recently - I had 3 devices, a DS3231 real time clock, a BME680 environmental sensor and a BNO055 inertial motion unit. I had a lot of trouble with the last one.
Two suggestions: First, use the i2cdetect and i2cdump utilities. The basic commands to check i2C bus 2 (pins P9_19 and P9_20) are: I2cdetect -l I2cdetect -r 2 You can google "i2cdetect BBB” to find more info. Using these rules out any problems with Python. If your device is not showing up, check your wiring. If it is showing up and i2cdump works too, then you may want to check the python libraries. Second, if you have access to an oscilloscope, use it to check SDA and SCL. My BNO was appearing in i2cdetect and working intermittently in Python. When I looked at it with the ’scope, it was clear that low to high transitions on SDA where taking far too long. A 1KΩ pull-up resistor fixed this (add it close to the sensor between SDA and 3V3). If you don’t have a scope, try adding the pull up resistor. My devices each had a 10KΩ pull up, but this was not enough. Be careful that the combined load does not exceed the 6 mA the BBB pins can safely sink. In case you need it, here’s the full list of python libraries I installed. The first one is included in a fresh install, but check to see if it needs upgrading. You can ignore the last 3 and use the one for your sensor instead. Nothing else is needed. There is a lot of old information still posted; these should work on a fresh install. Note the odd underscore in lis3dh is correct. sudo pip3 install Adafruit_BBIO -U sudo pip3 install adafruit_circuitpython-lis3dh sudo pip3 install adafruit-circuitpython-busdevice sudo pip3 install adafruit-circuitpython-register sudo pip3 install adafruit-circuitpython-ds3231 sudo pip3 install adafruit-circuitpython-bme680 sudo pip3 install adafruit-circuitpython-bno055 Hope this helps, -Steve > On Jan 25, 2021, at 8:06 AM, Astrid Hochart <ast...@qzabre.com> wrote: > > Hello everyone, > > I'm new to this subject but I'm trying to collect temperature data from this > sensor : https://www.mikroe.com/thermo-9-click by using Python and a > BeagleBone Black Rev C. The BBB is new and I don't have any SD card so I > flashed nothing on it. My problem is that when I connect the sensor (where I > moved the resistance to allow I2C mode) the BBB detects nothing : do you have > any idea why ? Should I "enable" I2C pins ? > > I'll be grateful if someone can help me. > > Best regards, > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/307d5c0a-d2ff-4f0a-a914-67ad2e4fdf92n%40googlegroups.com > > <https://groups.google.com/d/msgid/beagleboard/307d5c0a-d2ff-4f0a-a914-67ad2e4fdf92n%40googlegroups.com?utm_medium=email&utm_source=footer>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/26B1FAB2-B2A3-4E06-BAA6-3115856BB5AB%40gmail.com.
