The LM3S5651-IQC80-C0 is a 32-bit ARM Cortex-M3 MCU from the Stellaris® 5000 series, clocked at 80 MHz. It packs 128 KB of Flash and 32 KB of RAM, with USB OTG, CAN, and multiple serial interfaces. The 100-LQFP package exposes 67 GPIOs and a 16-channel 10-bit ADC, rated for -40 to 85 °C.
80 MHz Cortex-M3 — what it means for the control loop
At 80 MHz the Cortex-M3 executes a single-cycle multiply and a hardware divide, so a PID loop or a Modbus packet handler finishes in deterministic time. The 128 KB Flash is enough for a moderate firmware image with a real-time kernel; the 32 KB RAM leaves headroom for a few protocol buffers but not a full TCP/IP stack with large data arrays.
Obsolete — sourcing reality and replacement path
Connectivity and I/O — industrial gateway fit
USB OTG plus CAN and a full set of UART/SPI/I²C ports make this MCU a natural fit for an industrial gateway or an HMI controller that talks to both a fieldbus and a host PC. The 67 GPIOs in a 100-pin LQFP give enough headroom for a parallel LCD interface or a keypad matrix without an external port expander.