The STM32F051C8U6TR: 32-bit single-core MCU built around the ARM Cortex-M0 processor, running at up to 48 MHz.
Program memory is 64 KB of Flash, organized as 64K x 8 bits.
39 I/O and the peripheral set — what you can connect without external logic
With 39 I/O pins available, you can drive a 16x2 character LCD, read a dozen switches, and still have pins left for serial communication. The peripheral list includes DMA (for memory-to-peripheral transfers without CPU load), I²S (for digital audio), POR (power-on reset), PWM (for motor or LED dimming), and a watchdog timer. There is also an internal oscillator, so you can run without an external crystal for cost-sensitive designs, though accuracy will be lower.
Analog: 13-channel 12-bit ADC and one 12-bit DAC
Package: 48-UFQFN with exposed pad — hand-solderable?
The part comes in a 48-UFQFN exposed pad package (7x7 mm body).
The MCU operates from 2.0 V to 3.6 V on the Vcc/Vdd rail, which covers standard 3.3 V and 2.5 V logic levels.