How to use I2C with Pynq Z1?

Hi, I am not sure how you connect MSP430 to the board. If you build your own overlay and have your AXI IIC controller in your overlay, along with correct pin mapping in constraint file, you can use AXI IIC.

Otherwise, if you connect through Pmod/Arduino interface and want to use the base overlay, you will need to use microblaze IIC driver for it. Examples are here.