jktool-rs

Rust implementation of jktool — a command-line tool for communicating with JIKONG (JK) Battery Management Systems.

Supports the JK02 (24S/32S) and JK04 protocol variants, with automatic detection based on the BMS model string. Provides a reusable library (jk_bms) and a CLI (jktool).

Features

• Multi-transport: Serial, Bluetooth (optional), with the same transport:target syntax as the original
• Protocol support: JK02_24S, JK02_32S (PB2/BD/HY series), JK04 (auto-detected from info frame)
• Live data: Cell voltages, temperatures, SOC/SOH, power, errors, MOSFET states
• Settings read/write: Full register map with human-readable names, scaling, and write frame generation
• Output formats: Text, CSV, JSON (with pretty-print)
• BLE frame assembly: Handles fragmented BLE notifications with CRC verification
• Frame assembler: Reassembles 300-byte JK frames from small BLE MTU chunks

Building

cargo build

With Bluetooth support:

cargo build --features bluetooth

Usage

Transports are specified as transport:target[,options] — same syntax as the original jktool.

Serial

jktool -t serial:/dev/ttyUSB0,9600

Bluetooth

jktool -t bt:01:02:03:04:05:06,ffe1

Read live data (default)

jktool -t serial:/dev/ttyUSB0,9600

Read settings

jktool -t bt:01:02:03:04:05:06 settings

Write a setting

jktool -t serial:/dev/ttyUSB0,9600 set max_charge_current 50.0
jktool -t bt:01:02:03:04:05:06 set charging on

List supported settings

jktool list-settings

Output to file (JSON)

jktool -t serial:/dev/ttyUSB0,9600 -f json -o pack.json

Scan for Bluetooth devices

jktool scan

Library

The jk_bms crate provides the core protocol implementation:

use jk_bms::{MybmmPack, FrameAssembler, getdata, get_info_command, get_cell_info_command};

let mut pack = MybmmPack::new("pack1");
let mut assembler = FrameAssembler::new();

// Feed raw bytes from any transport
assembler.feed(&bytes);
if let Some(frame) = assembler.try_decode() {
    let flags = getdata(&mut pack, &frame);
    println!("Voltage: {:.3} V", pack.voltage);
    println!("Cells: {}", pack.cells);
}

Protocol versions

Version	Models	Cell voltages	Max cells
JK02_24S	JK-B2AxxS	2-byte LE mV	24
JK02_32S	JK_PB2, JK-BD, JK_HY	2-byte LE mV (16-byte offset)	32
JK04	Older JK-BMS	IEEE 754 float	24

Auto-detected from the BMS info frame model string.

License

MIT