Yes you can, but everything plugged into a digital port gets 12V power, even sensors that cant take that voltage.

I thought the voltage regulator limited the voltage on the digital ports to 5 volts

The V4 doesn't have regulators. EZ Robot will have a 5v regulator to connect between the board and 5v devices like sensors. Not showing in the store yet, but the developers kit will include one.

Dynamixel servos will not operate with less than 6 volts

I wanted to connect sensors to some of the digital ports without having to add an additional voltage regulator but if the i2c ports are 5 volts, I should be able to use sensors that use that protocol is that correct?

Thanks

There are some 5V pins on the V4 from what I've read. ADC ports and I2C ports have 5V available at them however the current is unknown. It may be possible to "borrow" the Vcc from these to power your sensors etc.

It's not best practice to do this though but it's an idea/option.

Currently I have an arduino nano that I'm using for all my sensors and I'm running dynamixel servos off of the original controller that came with the kit., just for the power. I communicate with both through a bluetooth, it was feeble attempt to replicate the EZ B V3 so I could use the dynamixel servos. I'm programming with python because I'm comfortable with it and using Opencv for the image processing but ARC is sooo much easier.

I'm tired of reinventing the wheel!

I really like what DJ and his team have created here.

It would have been awesome if at least some of the digital ports on EZB4 were power reg'd for 5v for sensors