Cortex-M3 core at 80 MHz with 512 KB flash
The LM3S1D21-IBZ80-A1 is a Stellaris-series ARM Cortex-M3 microcontroller running at 80 MHz — the 32-bit single-core pipeline delivers 1.25 DMIPS/MHz, so the effective throughput is about 100 DMIPS before flash wait-states cut in. The internal oscillator eliminates the external crystal for the core clock, though the RTC or USB (if used) still needs a 32.768 kHz watch crystal.
Peripheral set and connectivity options
67 GPIOs are available on the 108-ball BGA package, with an external bus interface (EBI/EMI) that can gluelessly connect to SRAM, NOR flash, or an FPGA over a 16-bit parallel bus. Serial connectivity covers I²C, SPI, SSI, UART/USART, IrDA, LINbus, and Microwire — enough to talk to sensors, displays, and fieldbus transceivers on the same chip. On-chip peripherals include an 8-channel 12-bit ADC, a PWM module for motor or LED control, a DMA controller for memory-to-peripheral transfers without CPU intervention, plus brown-out detect, POR, and a watchdog timer. The industrial temperature range (-40°C to 85°C) makes it suitable for factory-floor controllers and outdoor equipment enclosures.
Texas Instruments has marked the LM3S1D21-IBZ80-A1 as obsolete. No last-time-buy window remains open with the factory. For a BOM that already carries this MCU, the 108-BGA (10x10 mm) footprint and 1.235-1.365 V core rail are the critical dimensions for a drop-in replacement search. Any alternative must match the ball map and the narrow supply range to avoid a board spin.