The BA21 is a 32-bit low-power processor that delivers better performance than most processors of its size. Designed for deeply-embedded systems or as an auxiliary processor in larger systems, it is an especially effective choice for analog modules management, calibration, and configuration in energy- and cost-sensitive applications. The two-stage pipelined architecture minimizes standby/idle power and run-time energy consumption. The small silicon footprint of the CPU, and the smaller code memory requirement (due to the extreme code density of the BA2 instruction set), are critical for minimizing leakage currents during idle or standby modes and reducing dynamic power consumption. Furthermore, the processor allows for sophisticated power management, enabling dynamic clock gating or power shut off of unused units, and software or hardware controller dynamic frequency scaling of the bus and the CPU. Delivering more processing power per MHz than most processors in its class, the BA21 can be configured to operate at low frequencies to further save power, or to meet the most demanding embedded processing requirements, or any optimum combination of both. Its processing capabilities can be enhanced with the optional hardware multiplier, divider, multiply-accumulate, IEEE 754 compliant floating-point, and DSP instructions acceleration units. Interrupt response time can be optimized further with a vectored interrupt controller, and an optional memory protection unit can be used to protect application code and/or data from corruption. The system interface uses two AMBA? AXI4? or optionally two AHB-Lite? buses, one for data and one for instructions. Two tightly-coupled quick memory (QMEM) buses allow fast access for time-critical code and data, and can be used for inter-core communication in a multi-core architecture. The BA21 supports the variable instruction length BA2 instruction set, benefits from its extreme code density, and is binary compatible with other members of the BA2x processor family. Programing is facilitated with the included C/C++ tool chain, Eclipse IDE, architectural simulator, and ported C libraries. Advanced debugging capabilities and off-the-shelf development boards can further ease software development. Additional peripherals and bus infrastructure cores or complete subsystems can be ordered with the processor core to simplify SoC integration. Part of the royalty-free BA2x family, the BA21 processor core has been designed for easy reuse and integration, has been rigorously verified, and is production proven.