Your Bafang SW102 display, completely reprogrammed.

Open-source firmware that replaces the stock SW102 firmware entirely - a redesigned cockpit, a full settings menu, and Bluetooth OTA updates, built from scratch for genuine Bafang mid-drive controllers (BBS01/BBS02/BBSHD/M400/M420/M620).

View on GitHub → v0.0.9

nRF51822 · Free & open source · Bluetooth OTA updates

Cockpit

Everything a factory display shows - redesigned.

Battery voltage and percentage (Standard, or Precise - computed locally from measured voltage)
Speed, in large digits, with a selectable second layout that shows just the whole-number speed even larger
Motor power, in watts
Assist level - two selectable layouts, with a bar-graph or an arrow-based indicator, plus light/Bluetooth/brake status icons
Trip distance, odometer, and an estimated range based on your own riding history
Average and current energy consumption (Wh/km or Wh/mile)

Settings menu

A full menu, built from scratch.

Unit switch (km/h / mph), wheel size, speed limit, auto power off
Current and voltage calibration for shunt-modded controllers or an off-reading voltage divider
Odometer correction, trip reset, and full factory reset
Battery percentage mode (Standard or Precise) with configurable min/max pack voltage
Cockpit layout options - assist-level layout, indicator style, separators
Screen test and firmware/hardware info

Under the hood

Built for genuine Bafang controllers.

UART

Native Bafang protocol

Speaks the standard Bafang display UART protocol directly - no intermediate box, no adapter.

OTA

Bluetooth updates

Update the firmware over Bluetooth after the first flash - no need to open the display again.

Accurate battery %

Optional Precise mode computes the battery percentage locally from the display's own measured voltage, for controllers whose own reporting runs inaccurate.

Range estimator

A real energy-use model blends your riding history with your current style into a live range estimate - not a static number.

GPL

Open source

Built on top of the community anszom/SW102_LCD fork, itself GPL-3.0 licensed.

SIM

Terminal emulator

A Rust-based emulator compiles and runs the real firmware C code on a PC, for testing layout and logic without hardware.

MCU

nRF51822

Runs on the display's existing Nordic nRF51822 BLE SoC - no hardware modification needed.

Compatible controllers

BBS01/BBS01B, BBS02/BBS02B, BBSHD, M400, M420, M620/G510 Ultra - the standard Bafang display protocol family.

✓

Nothing leaves the display.

This is firmware, not an app - it has no internet connection of any kind. It talks to the motor controller over a wired UART cable, and to a phone over Bluetooth only for firmware updates (DFU) - nothing is ever sent anywhere online.

✓No internet connectivity, ever

✓No account, no analytics, no tracking

✓Bluetooth used only for firmware updates

✓Riding data stays on the display itself

Your Bafang SW102 display, completely reprogrammed.

Running on an actual SW102 display.

Everything a factory display shows - redesigned.

A full menu, built from scratch.

Built for genuine Bafang controllers.

Nothing leaves the display.

Get the firmware.