The AT32F421 is based on the high-performance ARM®Cortex®-M4 32-bit RISC core running up to 120 MHz. The Cortex®-M4 core features a full set of DSP instructions and a memory protection unit (MPU). The AT32F421 incorporates high-speed embedded memories (up to 64 Kbytes of internal Flash memory and 16 Kbytes of SRAM), enhanced GPIOs and peripherals connected to two APB buses. Any block of the embedded Flash memory can be protected by the “sLib”, functioning as a security area with code-executable only. The AT32F421 offers one 12-bit ADC, one analog comparator (CMP), five general-purpose 16-bit timers, one advanced timer and one low-power ERTC, as well as standard and advanced communication interfaces: up to two I 2C interfaces, two SPIs (all multiplexed as I 2S), two USARTs and one infrared transmitter. The AT32F421 operates in the -40 to +105 °C temperature range, from a 2.4 to 3.6 V power supply. A comprehensive set of power-saving mode allows the design of low-power application. The AT32F421 offers devices in different package types. Depending on the different packages, the pin-to-pin is completely compatible among devices, and also the software and functionality. Only different sets of peripherals are included