The LM3S101-IQN20-C2T is a Stellaris ARM Cortex-M3 core running at 20 MHz. With 8 KB of flash and 2 KB of SRAM, it fits control loops, UART-to-SPI bridges, and simple sensor aggregation — not a GUI stack or heavy protocol handler. Eighteen general-purpose I/O lines and internal oscillator mean you can start a basic design without an external crystal or a large BOM. The 48-LQFP package (7x7 mm) is hand-solderable and routes on two-layer boards if you keep the fan-out clean.
If your design has legacy 5 V peripherals, budget a level shifter or use open-drain with pull-ups to 3.3 V. Not rated for under-hood automotive or engine-bay environments.
The base product number LM3S101 covers the whole family; the -IQN20-C2T suffix identifies the 20 MHz speed grade, industrial temp, and 48-LQFP package variant.