GPIO minimum voltage

What’s the minimum voltage that can be applied to the GPIO for them to be seen as HIGH?

Table 9 in shows it’s expecting 3.3V, but what’s the minimum that could work?

I have a board that supposedly outputs 3.3V but sometimes it’s closer to 2.7V, and it seems the Lime doesn’t notice it when it’s that low.

Probably a silly question, but what is the voltage on pin 2, is it 3.3 volts ?
Could it be a power issue where the LimeSDR is not getting enough power and what it thinks is 3.3 volts is a lower voltage. And because of that it is not behaving like a standard 3.3v CMOS&TTL for Vih.

Here my other “board” is an Arduino, and when I check what that Arduino outputs, it’s sometimes quite low, around 2.7V. When it’s like this, the Lime doesn’t see the GPIO as HIGH.

I’ll check the voltage on pin 2 when I’m back at my computer.

@andrewback @Zack Do you have any idea on the minimum voltage required for the Lime to detect it?