The TI MSP430™ family of ultra-low-power microcontrollers consists of several devices featuring different sets of peripherals targeted for various applications. The architecture, combined with extensive low-power modes, is optimized to achieve extended battery life in portable measurement applications. The device features a powerful 16-bit RISC CPU, 16-bit registers, and constant generators that contribute to maximum code efficiency. The digitally controlled oscillator (DCO) allows the device to wake up from low-power modes to active mode in 3.5 µs (typical). The MSP430F522x series are microcontrollers with four 16-bit timers, a high-performance 10-bit ADC, two universal serial communication interfaces (USCIs), a hardware multiplier, DMA, a comparator, and an RTC module with alarm capabilities. The MSP430F521x series include all of the peripherals of the MSP430F522x series with the exception of the ADC. All devices have a split I/O supply system that allows for a seamless interface to other devices that have a nominal 1.8-V I/O interface without the need for external level translation. For complete module descriptions, see the MSP430F5xx and MSP430F6xx Family User’s Guide. For design guidelines, see Designing With MSP430F522x and MSP430F521x Devices.