It can be a challenge to interface 5volt stuff with modern 3.3volt microcontrollers like an ARM or MSP430. This app note covers several circuits for voltage translation on input, output, and bidirectional pins.
The interfacing of the 3-V MSP430x1xx and MSP430x4xx microcontroller families to circuits with a supply of 5 V or higher is shown. Input, output and I/O interfaces are given and explained. Worst-case design equations are provided, where necessary. Some simple power supplies generating both voltages are shown, too.