BMS STM32F412 + ADBMS6830

Simple Battery Management System firmware for an STM32F412 master board using Analog Devices ADBMS6830 battery-monitor ICs.

The project reads cell voltages, temperatures, current sensor data and contactor feedback, then sends the important information over CAN to the Powertrain Bus.

Main hardware

• STM32F412RET6 microcontroller
• ADBMS6830 battery monitoring ICs
• isoSPI daisy chain for the BMS slaves
• CAN bus for telemetry and commands
• External EEPROM for saved configuration
• IVT-S current / voltage sensor
• Precharge, AIR+, AIR- and discharge contactors
• PWM fan output

Main features

• Cell voltage measurement
• Thermistor temperature measurement
• Open-wire detection
• Passive cell balancing
• Precharge state machine
• Contactor feedback service
• CAN telemetry using powertrain_t26.dbc
• Fault manager with active fault tracking
• SOC estimate using cell voltage and IVT-S ampere-second counter
• UART debug output using DMA
• Watchdog reset detection
• CAN bootloader jump command

Basic firmware flow

1. main.c initializes the STM32 peripherals.
2. brain_start() initializes CAN, EEPROM, fan control, analog readings, IVT-S, precharge and fault handling.
3. brain_loop() runs forever.
4. Depending on the BMS state, the firmware reads the ADBMS6830 chain, balances cells, checks faults and sends CAN messages.
5. If a serious fault happens, the system can open the contactors and move to a safe state.

CAN communication

The firmware uses the powertrain_t26.dbc and handcart_t26.dbc files.

CAN is used for:

• Slave cell voltages
• Slave temperatures
• Module status
• Master board status
• Fault reporting
• IVT-S sensor readings
• Precharge commands
• Cell balancing commands
• Bootloader jump command

Cell balancing

Balancing is passive and controlled through the ADBMS6830 discharge outputs.

The firmware:

• Finds the lowest valid cell voltage in the Accumulator
• Compares every cell against that minimum
• Enables discharge on cells that are too high
• Stops balancing when the cells are inside the configured delta

Fault handling

The fault manager tracks active faults and stores context such as:

• Time of the fault
• Measured value
• Threshold value
• Slave index
• Cell index
• CAN channel
• Contactor mismatch bits

Faults are also sent over CAN.

Build target

This project is made for STM32CubeIDE / STM32 HAL and targets:

STM32F412RET6