80 MHz Cortex-M4 with 128 KB Flash — the mid-range STM32L4 sweet spot
The STM32L431RBT6TR: It belongs to the STM32L4 series, ST's ultra-low-power line built on a 40 nm process, targeting battery-operated and energy-harvesting designs where every microamp matters.
Memory map and analog front-end
The 128 KB Flash and 64 KB SRAM partition leaves roughly 40-50 KB of SRAM free after a typical RTOS and HAL footprint, which is adequate for a 16-channel ADC scan buffer or a small audio frame. The 52 GPIOs in the 64-LQFP package give enough headroom for a parallel LCD interface or a bank of pushbuttons and LEDs alongside the serial peripherals.
Connectivity and peripheral set
The STM32L431RBT6TR includes CANbus, multiple I2C and SPI ports, UART/USART with LIN and IrDA support, plus a Quad-SPI interface for external Flash — a connectivity set that covers industrial fieldbus and sensor networks. A dedicated SAI (serial audio interface) and SWPMI (single-wire protocol master interface) are also present, expanding the part's reach into audio processing and smart-card reader applications.
The part is ROHS3 compliant, meeting the latest EU directive on hazardous-substance restrictions.