In this paper a complete implementation and design of a fully-synthesized 32-bit microcontroller in a 130nm CMOS technology is presented. This is the first microcontroller featuring the open source RISC-V instruction set all mounted through AXI4-Lite and APB buses for communication process. The microcontroller contains a 10-bit SAR ADC, a 12-bit DAC, an 8-bit GPIO module, a 4kB-RAM, an SPI AXI slave interface for output verification, and an SPI APB slave interface for checking the correct behavioral of the APB bridge. All peripherals are controlled by a RISC-V and an SPI AXI master interface that is used for programming the device and checking the data flowing through all the slaves. A total power density is reported as 167μW/MHz and the area for this RISC-V microcontroller has a reduced footprint of 798μm×484μm.