What the 50MHz Cortex-M3 means on a legacy board
The LM3S1H16-IQR50-A1T is a Texas Instruments Stellaris ARM Cortex-M3 MCU clocked at 50MHz — that is the core speed ceiling, not the flash access speed. With 512KB of program Flash and 48KB of RAM, it fits firmware images that outgrew smaller Stellaris parts without a board spin. The 32-bit single-core Cortex-M3 handles the Thumb-2 instruction set, so code density is tighter than a pure ARM32 core — useful when the Flash is already half-full with a legacy application.
Memory and I/O for a field-swap decision
512KB of on-chip Flash and 48KB of SRAM (organized as 48K x 8) give this MCU enough room for a moderate control stack plus a small data logger. If your existing firmware image is near 480KB, this part still fits; if it crossed 512KB, you need a larger Flash variant in the same package. 33 general-purpose I/O lines in the 64-LQFP package — the 10x10mm body with 0.5mm pitch is a common footprint. The pinout is the same across several Stellaris parts in the same package, so a layout swap between siblings is possible without a respin. Connectivity covers I²C, SPI, SSI, UART/USART, LINbus, IrDA, and Microwire — enough for a sensor hub or a motor drive interface. The 8-channel 12-bit ADC samples at rates adequate for current sensing or temperature monitoring in an industrial control loop.
Obsolete — sourcing reality for the BOM line
Texas Instruments lists this part as Obsolete. The part is sourced through independent distribution channels — quantities are lot-specific and confirmed at RFQ.