How do you determine ID of an I2C peripheral when using machine library

Arduino Boards
1

I am using OpenMV on an Arduino Nicla Vision and am trying to use the machine.I2C class.

From the TOF sensor example I can see that the I2C ID is 2

from machine import I2C
tof = VL53L1X(I2C(2))

Where can I find that ID in the documentation?

I was trying to use the external I2C port (the one on the header) and I determined by trial and error that it’s ID was 1.

I assume that is in a config file somewhere ,but don’t know where to look.

I can see some reference to I2C_ID in the file openmv/omv_boardconfig.h at master · openmv/openmv · GitHub, but I don’t see a value for the TOF sensor and ID =1 is the FIR (not sure what this is on the Nicla Vision)
#define FIR_I2C_ID (1)

2

It’s not documented anywhere as far as I know, you can find which bus connects to what from the schematics.

3

Ok, thx. I can see the I2C connections on the schematic.

I was just thinking that since the OpenMV IDE handles multiple boards that there must be a file that indicates what the IDs are for the different boards. Like the variant pin files on the Arduino IDE.

I thought the file that I referenced “openmv/src/omv/boards/NICLAV/omv_boardconfig.h” was the correct place to look, but it doesn’t correlate exactly to the schematic. I’ll just accept that there is some sort of magic that gets that done.

4

If you just want to know what I2C are available/enabled for MicroPython, see:

However, this doesn’t tell you which devices are on which bus, it’s just the list of enabled buses.

5

Thanks, that’s helpful.