NANO 33 BLE I2C problems (caused in mbed Wire.cpp) - read/write bit on I2C scan

[ratio-x]

Are you experienced with pullups on NANO 33 BLE?

I'm working throughout with 3,3 V and 100 kHz on the I2C bus.
The schematics file shows 2x 4k7 on SDA1/SCL1 (internal I2C bus).
For me it's not clear, if the external I2C bus has built-in pullups. From schematics I would say no, multimeter reading shows a resistance of around 10M.

Not sure if pinMode is applicable on analog pins, so I tried this (without any effect noticable):

pinMode(A4, INPUT_PULLUP);   // SDA
pinMode(A5, INPUT_PULLUP);   // SCL

I tried with external resistors (2x 4k7 and 2x 2k2) on SDA/SCL, without any effect.

I found two more hints here

Fully understand pins_arduino.h for the Nano 33 BLE

Klaus_K: Power pins are not accessible by software, so they are not defined. The controller has more physical pins than the module/pcb. Some of these pins are connected on the pcb. For instance there is a RGB LED right next to the BLE module. I suspect copy and paste from different sources. Thanks Klaus_K. Your answers are very useful. I was suspecting the copy and paste from different sources, as I tried (3u), (3), 3 and all seemed to work for redefining something. I am also starting to…

and here

Cannot connect to I2C accelerometer sensor

but I'm not sure about how to apply.

pinMode(PIN_ENABLE_I2C_PULLUP, OUTPUT);

P1_0 pin, which is the pullup for the I2C bus

If ghost addresses are an indicator for non present or too high pullup resistors on SCL/SDA, what else could I try if 2x 2k2 did not help? Just ignoring, because communication with present I2C devices is possible without glitches?