EFM8BB51 & EFM8BB52 Busy Bee 8-bit MCUs Silicon Labs EFM8BB51 and EFM8BB52 Busy Bee MCUs are multi-purpose microcontrollers with a comprehensive feature set in compact packages. These devices offer high value by integrating advanced analogue and communication peripherals into a small footprint, making them ideal for space-constrained applications. With an efficient 8051 core, 5V capable I/O, precision analogue and enhanced pulse-width modulation, the EFM8BB51 and EFM8BB52 MCUs are optimal for embedded applications.