Using 1.8V and 5V expansion leads to strange behavior

I’m trying to drive an external DAC via I2C with a level shifter. I use the 5V pin as power (it’s just a DAC so current draw is minimal) and 1.8V pin as reference from the expansion headers. However, when I connect them both to my level shifter the screen changes to a yellowish hue and the file system suddenly becomes read-only. I can see the device with i2cdetect and write to it sometimes but the OS usually needs a reboot just a few seconds after connecting these 2 pins to my board. Disconnecting one of the two causes the screen to return to normal but the file system remains read only.

I’m on a Beagleboard xM rev C running Xubuntu.

Does anyone know what could be causing this?

Thank you,

Any chance you could provide a schematic?




Well, I have no idea. Looking at this schematic, I do not see the BeagleBoard connector at all. Looking at what you have seems OK. Are you using the expansion header or the LCD headers?


I don’t see any capacitors on power lines.
Second, what type of level shifter do you use?

It’s hard to find a black cat in a dark room