The STM8L151G3U6TR is an 8-bit STM8 microcontroller from the STM8L EnergyLite series, built for battery-powered and thermally constrained applications where every microamp matters. It runs at 16 MHz from a 1.8 V to 3.6 V supply, packing 8 KB of Flash program memory, 1 KB of RAM, and 256 bytes of EEPROM — enough for a sensor node firmware image with calibration tables stored in the nonvolatile EEPROM block. The 28-pin UFQFPN package (4x4 mm) keeps board area small, while the 18-channel 12-bit ADC lets you multiplex multiple analog inputs without an external mux.
On the board — package and power
Hand-rework needs a hot-air station and a microscope; the pad pitch is tight enough that solder bridging between adjacent pins is a real risk without proper stencil design. The internal oscillator saves an external crystal for many applications, though the I²C and SPI peripherals will benefit from the external clock if tight timing accuracy is required.