EFM8BB Busy Bee 8-Bit Microcontrollers Silicon Labs EFM8 EFM8BB Busy Bee 8-Bit Microcontrollers provide state-of-the-art performance by integrating 12-bit ADC, internal temperature sensor, and up to two 12-bit DACs into small packages. Using an efficient, pipelined 8051 core with maximum operating frequency at 50MHz, various communication interfaces, and four channels of configurable logic, the Silicon Labs EFM8BB MCUs are well-suited for many embedded and general-purpose applications.