I2c0 issues, i2c1 working

Products Support DragonBoard410c
#1

for some reason i2cdetect is only showing devices on i2c1 and not on i2c0, is this a known issue? using the latest debian 17.06.1

#2

Hi @ric96

In my setup(DB410c + Sensors Mezzanine) i2cdetect is showing devices connected to both i2c-0 and i2c-1 bus correctly.

I cannot test it directly without any mezzanine due to lack of 1.8v compatible sensors.

However, if you are using Sensors Mezzanine you should note that i2c-0 is 5v compatible and i2c-1 is 3.3v.

Thanks,
Mani

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#3

It’s working now. I was using the Audio Mezz, It’s electronically not very sane and has issues with it’s level shifting. It’s mow working with an external Logic level shifter
thanks

#4

FYI - The Level shifters on the Audio Mezzi are ‘active’ with speed-up circuits to improve the peak speeds. This is good if you are interfacing with fast devices, but bad if you have a long cable (15cm or more). The outputs of the level shifters break into oscillation when you attach a long cable due to the impedance discontinuity at the end of the wire. if you keep the leads really short (<2cm) the level shifters on the Audio Mezzi work fine.

Full disclosure: I am an employee of Qualcomm Canada, any opinions I may have expressed in this or any other post may not reflect the opinions of my employer.

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Connecting MCP3008 and Dragonboard
#5

that sort of defeats the purpose then… :frowning:
until I have a board design to go directly on top of the audio mezz, I can’t use the 5v gpio. and if I am going to design a board anyway, why would I do it specifically for the audio mezz, and not design a 1v8 compatible board for db410c