BQ76952 Battery Monitor Library (STM32, no_std, Rust)

This project provides a Rust implementation of the Texas Instruments BQ76952 3‑to‑16‑cell battery monitor and protector.

It is based on TI’s reference documentation, rewritten to use no_std and embedded-hal traits with a mockable I²C interface.

The goal is to expose a safe, typed API for configuration, telemetry, protection, and FET/balancing control.

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Purpose of the Library

TI’s BQ76952 uses a command/data‑memory architecture that requires:

• structured subcommands
• checksummed data‑memory writes
• specific sequencing rules

Vendor examples often rely on blocking I²C and manual register handling.

This Rust port provides:

• a no_std Rust API
• safe data‑memory access with automatic checksum
• predictable behavior under concurrency
• compatibility with any embedded-hal I²C backend
• a fully testable driver using mock I²C interfaces

The functional behavior matches TI’s reference implementation.

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Upstream Source

This driver is based on:

• https://github.com/skriachko/bq76952

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Hardware

• Monitor/Protector: Texas Instruments BQ76952
• Cells: 3–16 series Li‑ion / Li‑polymer / LiFePO₄
• Target MCU: STM32 (or any embedded-hal compatible MCU)
• Interfaces: I²C, ALERT pin, TSx thermistors, FET drivers, cell inputs

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Rust Setup

The driver uses:

• embedded-hal for I²C
• no_std
• mockable I²C for testing

It exposes:

• register access
• subcommand access
• data‑memory read/write
• voltage, current, temperature telemetry
• protection configuration
• permanent fault monitoring
• FET and cell‑balancing control
• security/unseal handling
• sleep/shutdown mode control

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Telemetry

The BQ76952 provides:

• Cell voltages (1–16)
• Stack voltage
• Min/max cell voltage
• Current measurement (CC2)
• Temperatures: internal die, TS1/TS2/TS3, HDQ, DCHG, DDSG

Kelvin‑to‑Celsius helpers included.

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Protection Modes

Supported protection categories:

• Cell overvoltage / undervoltage
• Charge/discharge overcurrent
• Short‑circuit protections
• Temperature protections
• Permanent Faults (PF)

The driver exposes:

• Safety Status A/B/C
• PF Status
• threshold and delay configuration
• recovery behavior

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Security States

The BQ76952 supports:

• Sealed
• Unsealed
• Full Access

The driver includes unseal key handling and state tracking.

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FET & Balancing Control

Supported operations:

• Charge FET
• Discharge FET
• Combined FET control
• Manual cell balancing

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Power Modes

Supported:

• Normal
• Sleep
• Shutdown

Driver includes helpers for entering/exiting modes.

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Data Memory Access

The BQ76952 uses a structured data‑memory map with checksums.

The driver provides:

• safe read/write
• automatic checksum
• typed accessors
• raw access for advanced configuration

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Examples

• monitor — full monitoring loop: voltages, current, temperatures, safety status

Run examples:

cargo run --example monitor

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Documentation

• BQ76952 Technical Reference Manual
  https://www.ti.com/lit/ug/sluuby2a/sluuby2a.pdf (ti.com in Bing)
• Datasheet
  https://www.ti.com/lit/ds/symlink/bq76952.pdf (ti.com in Bing)
• Software Development Guide
  https://www.ti.com/lit/an/sluaa11a/sluaa11a.pdf (ti.com in Bing)