80 MHz Cortex-M4 with FPU — compute headroom for sensor fusion and control loops
The STM32L431CBY7TR: The 49-WLCSP package measures 3.14 x 3.13 mm. The 80 MHz Cortex-M4 core includes a single-precision FPU and DSP instructions, giving it the compute margin for sensor fusion, motor-control FOC loops, or audio processing without offloading to a separate DSP. The 128 KB Flash is adequate for mid-complexity application code with a RTOS; the 64 KB SRAM leaves room for several large buffers or a modest heap.
WLCSP package — PCB layout and rework considerations
The 49-WLCSP package requires a fine-pitch PCB footprint and solder-mask-defined pad layout.
Peripheral set — CAN, QSPI, multiple serial interfaces
Connectivity includes CANbus, I²C, SPI, UART/USART, QSPI, SAI, and SWPMI — enough for gateway nodes, multi-sensor aggregators, or human-machine interfaces.
The base product number STM32L431 covers multiple Flash and package variants, so the family roadmap is stable.