Cortex-M3 core at 20 MHz — on-chip memory budget
The LM3S101-IGZ20-C2T is a Stellaris® ARM® Cortex®-M3S 100 microcontroller from Texas Instruments, built around a 32-bit ARM Cortex-M3 core clocked at 20 MHz. The 8 KB on-chip Flash and 2 KB SRAM define the application ceiling: a lightweight control loop with a small state machine fits comfortably, but a full RTOS with a TCP/IP stack overflows the RAM budget before the first task runs.
Package, footprint, and thermal pad
The exposed paddle is the primary thermal path — a layout without the via pattern leaves the die near the abs-max junction temperature at full load in a 85°C ambient.
Peripheral set and serial interfaces
On-chip serial connectivity includes Microwire, SPI, SSI, and UART/USART — enough for a SPI flash, a UART debug console, and a sensor interface without external GPIO expansion. Internal oscillator eliminates the external crystal for cost-sensitive BOMs, though the accuracy is lower than a ceramic resonator for timing-critical CAN or USB applications (neither is on this part). Brown-out detect, POR, PWM, and WDT are built in, reducing the need for external supervisory ICs.