Smart BMS Circuit Design

I need a compact Battery-Management System circuit that can talk seamlessly to either an ESP32 or an STM32 host, leaving me free to drop the module into different projects later. Communication over I2C is my first choice because it keeps wiring simple, yet I will accept SPI or UART if you can explain the trade-offs.

Core protection functions must be built in: over-charge, over-discharge and temperature safeguards. On top of that I also require active or passive cell balancing plus precise single-cell voltage measurement for 4- to 5-series-cell packs.

Please deliver:

• Complete, production-ready schematic
• Annotated bill of materials with readily available parts
• Brief firmware example that shows register map / commands for the chosen protocol so I can verify data from each cell on an ESP32 or STM32

Design files in KiCad, Altium, or a comparable mainstream EDA are fine as long as I receive the editable source. Documentation should let me move from prototype to small-scale manufacturing without guesswork.