component

Modular BMS

Public Made by Adom

by adom

Modular Battery Management System — a composable BMS built from Adom molecules. TI BQ76952 monitor/protector with MSP430 host firmware, supporting 18650 cylindrical and EVE LF105 prismatic cell carrie

hardwarebmsbatterybq76952msp430platformio18650lifepo4modular
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Modular BMS

A composable Battery Management System built from Adom molecules. Uses the TI BQ76952 battery monitor/protector IC with an MSP430 host MCU, supporting both 18650 cylindrical and EVE LF105 prismatic LiFePO4 cell carriers.

System Architecture

The Modular BMS is composed of the following molecules:

Molecule Purpose
molecule-bq76952-v2 BMS brain — BQ76952 monitor, FET control, cell balancing, protection
molecule-18650-battery Dual 18650 cylindrical cell carrier (Keystone 54 holders)
molecule-18650-jumper Series interconnect between 18650 carriers
molecule-eve-lf105-prismatic EVE LF105 105Ah prismatic LiFePO4 cell carrier

Requirements

  • Minimum 3 cells in series
  • MSP430F5529LP eval board (for SBW programming)
  • BQ76952EVM or the BQ76952 BMS Molecule v2

Firmware

The MSP430 firmware lives in PlatformIO/MSP430_BQ76952/ and provides:

  • I2C communication with the BQ76952 (UCB1: P4.4=SCL, P4.5=SDA)
  • UART telemetry output (UCA1: P4.2=RX, P4.3=TX) in human-readable or JSON format
  • Periodic cell voltage, current, and temperature readings
  • CHG/DSG FET control via GPIO buttons (P3.3=DSG, P3.4=CHG)
  • Full protection monitoring (OV, UV, OCD, SCD, PF)
  • Configurable n-cell mode via VCellMode

Build & Flash

# Install PlatformIO, conda with Python 2.7 for MSP430 toolchain
conda create -n py27 python=2.7
conda activate py27
export LD_LIBRARY_PATH="/root/miniconda3/pkgs/python-2.7.18-h42bf7aa_3/lib:$LD_LIBRARY_PATH"

# Build and upload
pio run -t upload

Cell Count Configuration

Default is 3S. To change, edit in main_MSP430FR2355_I2C.cpp:

#define NUM_CELLS 3
#define NUM_CELLS_BITS 0x0007   // enable Cell1..Cell3

Output Modes

set_output_mode(OUTPUT_HUMAN);  // readable console logs
set_output_mode(OUTPUT_JSON);   // Hydrogen-style JSON notifications

Notes

  • To reset the system, power cycle the MSP EZ-FET Lite molecule
  • If the BQ76952 is stuck, pull RST_SHUT high (or to REG1)
  • PACK pin voltage reads ~0V when FETs are open (normal)
  • Current is signed — cast CC2Current to int16_t

Source