50 MHz Cortex-M0 — USB throughput without stalling
The 50 MHz core speed on the Cortex-M0 is enough to handle USB interrupt-driven transfers without the CPU stalling on every packet. For designs running a USB HID or CDC class, the combination of a 50 MHz clock and the USB engine keeps the bus responsive without needing a DMA workaround.
32 KB Flash and 6 KB RAM — firmware budget
With 32 KB of Flash and 6 KB of RAM, the firmware footprint must be managed. The USB stack, application code, and bootloader together need to fit inside that 32 KB. The 6 KB RAM is tight for large data buffers — plan to stream data rather than buffer entire packets.