Smart 4-Cell Li-ion BMS

I’m building a college prototype powered by one to four 18650 Li-ion cells (3.6 V-3.7 V nominal, 4.2 V full) and I need a compact, smart BMS board that I can drop straight in. The circuit must monitor each cell individually, balance them during charge, and guard the pack against over-voltage/under-voltage, over-current/short-circuit, and temperature events.

All cell-level data has to reach an ESP32 or STM32; I’d like the primary interface to be I²C, though UART or SPI compatibility is welcome if it comes for free. Low quiescent current matters because the board will stay wired even when the system’s off. A clear register map or simple firmware hooks are essential so I can pull per-cell voltages, pack voltage, current, and thermistor readings inside my own code.

Here’s what I need from you:
• Schematic built around proven BMS/AFE parts (feel free to suggest TI BQ-series, LTC, or your favourite alternative)
• PCB layout with Gerber and drill files, sized for a four-cell holder
• Fully annotated BOM with globally available part numbers
• Firmware (if a local MCU is used) or configuration guide that lets me read/write the BMS over I²C from my host MCU

Acceptance checks on my bench:
1. Individual cell voltages appear on the ESP32/STM32 within ±10 mV of a DMM reading.
2. Balancing engages when any cell exceeds 4.15 V by ≥20 mV.
3. Protections trip at roughly 4.25 V or 2.5 V per cell, 7 A discharge, or 70 °C, then recover without a reset once conditions return to normal.

Please include a quick note on the ICs/topology you plan to use and how the I²C register set will look so I can be sure it aligns with my firmware timeline. I’m aiming for a clean, reproducible design that I can present confidently at university and then send straight to fabrication.