Sometimes a single requirement is going eliminate a whole range of MCU chips.

For example, suppose you need four 16-bit hardware timers.

Or four UARTs.

Or sixteen ADC inputs.

(Assuming you want all in the one MCU.)

 

Sometimes a single requirement is going eliminate a whole range of MCU chips.

For example, suppose you need four 16-bit hardware timers.

Or four UARTs.

Or sixteen ADC inputs.

(Assuming you want all in the one MCU.)

Indeed. In my last application I needed 4 hardware timers, an UART, an ADC, SPI, and like 10 GPIOs. Those requirements fastly helped me select the MCU. For the timers, STM32 family is pretty good at it.