Flash and SRAM sizing for firmware strategy
The 64 KB SRAM (organized as 64K x 8) provides enough buffer space for Ethernet packet handling (two full 1500-byte frames plus protocol overhead) and a modest heap for dynamic allocation. If your application requires over-the-air update staging, budget the Flash footprint: the bootloader plus two image slots typically consume 200-300 KB, leaving 200+ KB for the active application.
Boot and debug considerations
The Cortex-M3 boots from internal Flash with BOOT0 sampled at reset; the JTAG/SWD debug port remains active even with the watchdog enabled, which simplifies firmware bring-up. The 80 MHz PLL requires adjusting Flash wait states before raising the core clock above the default speed — failing to do so causes a hard fault on the first instruction fetch from Flash. The internal oscillator provides a 12 MHz reference for the PLL, but for Ethernet applications requiring precise timing, an external crystal should be considered.