Q: Why did you choose this particular MCU?
A: STM32 in one of the most popular ARM Cortex-M implementations. The STM32 MCU family offers a wide variety of options and advanced peripherals. STM32F091 is the smallest and cheapest MCU in the family with six hardware UART ports, which makes it perfect for hexagonal (and smaller shapes). Some modules might use bigger MCUs to get more hardware resources but STM32F091 is suitable for most of our modules.