I am trying to interface a single bidirectional data pin cheaply and with as little components as possible.
On each side I have an AVR, so I can use the pullup on its GPIO pin if that helps/eliminates any external components.
One AVR will be running 5V from USB, the other AVR might be 2.5V-5V. I plan on having each AVR switch between input with pullup enabled OR output ground.
The thing is that I only want a 2 pin connection to the 2.5V-5V AVR. Ground and data. I found this BSS138 shifter, but it shows LV coming from the lower voltage device which would be 3 pins which I don't want.