https://github.com/scttnlsn/bms
Battery management system for 4-series li-ion packs
https://github.com/scttnlsn/bms
arm battery battery-management-system bq76920 cortex-m zephyr
Last synced: 6 months ago
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Battery management system for 4-series li-ion packs
- Host: GitHub
- URL: https://github.com/scttnlsn/bms
- Owner: scttnlsn
- Created: 2017-08-07T17:30:05.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2021-06-16T19:03:17.000Z (over 4 years ago)
- Last Synced: 2025-03-23T20:43:43.636Z (7 months ago)
- Topics: arm, battery, battery-management-system, bq76920, cortex-m, zephyr
- Language: C
- Homepage:
- Size: 210 KB
- Stars: 56
- Watchers: 8
- Forks: 31
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# BMS
Integrated battery management system for 4-series li-ion packs (based on the [BQ76920](http://www.ti.com/product/BQ76920) from Texas Instruments).
* programmable over/under voltage protection for each cell
* programmable short-circuit detection
* auto cell balancing
* cell voltage monitoring
* coulomb counting for accurate state-of-charge tracking
* status available over BLE
## Hardware
Full schematic and PCB layout available in the `hardware` directory.
* [TI BQ76920](http://www.ti.com/product/BQ76920) analog front-end
* [Nordic nRF51822](https://www.nordicsemi.com/eng/Products/Bluetooth-low-energy/nRF51822) ARM Cortex-M host controller
* FETs for enabling or disabling charge/discharge
* shunt resistor for current measurement
## Firmware
The host controller firmware is based on the [Zephyr RTOS](https://www.zephyrproject.org). It communicates with the BQ76920 via I2C and handles various error states that may occur in the BQ76920. It also exposes a BLE peripheral for wireless monitoring.
### Build
Requirements:
* [GNU ARM Embedded Toolchain](https://developer.arm.com/open-source/gnu-toolchain/gnu-rm)
* [OpenOCD](http://openocd.org)
* [Zephyr RTOS](https://www.zephyrproject.org) (included as submodule)
* [elftools](https://github.com/eliben/pyelftools)
Setup:
* `git submodule update --init`
* `./setup.sh`
Compile and flash:
* `make`
* `make flash`
### Configuration
There are various configuration options which can be specified via Kconfig. Run `make menuconfig` to browse the available options and override any of the default values.
* `CONFIG_BMS_BOOT_DEVICE` (default: `GPIO_0`)
* `CONFIG_BMS_BOOT_PIN` (default: `21`)
* `CONFIG_BMS_ALERT_DEVICE` (default: `GPIO_0`)
* `CONFIG_BMS_ALERT_PIN` (default: `22`)
* `CONFIG_BMS_BLINK_DEVICE` (default: `GPIO_0`)
* `CONFIG_BMS_BLINK_PIN` (default: `18`)
* `CONFIG_BMS_OVP_ENABLE` (default: `3550` mV)
* `CONFIG_BMS_OVP_DISABLE` (default: `3350` mV)
* `CONFIG_BMS_UVP_ENABLE` (default: `3000` mV)
* `CONFIG_BMS_UVP_DISABLE` (default: `3100` mV)
* `CONFIG_BMS_SCD_DELAY` (default: `10000` ms)
* `CONFIG_BMS_OCD_DELAY` (default: `10000` ms)
## BLE Protocol
The BMS implements a Bluetooth Low Energy peripheral for monitoring cell voltages, current draw and state-of-charge. All status data is part of a single characteristic.
Peripheral UUID: `8D9D7800-5B61-412A-AB71-5C7E0E559086`
Characteristic UUID: `8D9D7801-5B61-412A-AB71-5C7E0E559086`
Value structure (MSB to LSB):
* status [1 byte]
* cell 1 (mV) [2 bytes]
* cell 2 (mV) [2 bytes]
* cell 3 (mV) [2 bytes]
* cell 4 (mV) [2 bytes]
* current (mA) [2 bytes signed]
* charge used (mAs) [4 bytes signed]
* state of charge (percent) [1 byte]