System Architecture

LibreScoot runs on two embedded Linux computers that communicate via Redis over USB Ethernet.

Overview

MDB · Middle Driver Board 192.168.7.1
vehicle-service battery-service ecu-service bluetooth-service alarm-service modem-service uplink-service update-service pm-service keycard-service settings-service version-service boot-led-service ums-service onboot-service
Redis
Battery BMS (I2C) · NFC · 4G Modem · GPS
USB Ethernet
DBC · Dashboard Computer 192.168.7.2
scootui dbc-backlight-service carplay-service brightness-reader valhalla update-service version-service onboot-service
Display · Sensors
CAN Bus
ECU

The Two Computers

MDB - Middle Driver Board

The main controller. Talks to the ECU, batteries, NFC reader, modem, and nRF52 co-processor.

Hardware interfaces:

  • CAN bus (ECU communication)
  • I2C/GPIO (battery BMS, sensors)
  • NFC reader (keycard authentication)
  • 4G modem (cellular connectivity)
  • GPS receiver

Key services:

  • vehicle-service - State machine, lock/unlock, LED control
  • battery-service - BMS communication, charge monitoring
  • ecu-service - Motor controller (Bosch/Votol)
  • uplink-service - Remote telemetry and commands
  • alarm-service - Motion detection

DBC - Dashboard Computer

Handles the user interface, navigation, and display.

Hardware interfaces:

  • LCD display (480x480)
  • Ambient light sensor

Key services:

  • scootui - Flutter dashboard UI
  • dbc-backlight-service - Display brightness control
  • carplay-service - CarPlay dongle support

Redis IPC

Services communicate through Redis pub/sub and hash fields. The redis-ipc library provides a common interface.

Key patterns:

  • State hashes - vehicle, battery:0, engine-ecu
  • Command queues - scooter:state, scooter:power
  • Pub/sub channels - Real-time state change notifications

The MDB runs the primary Redis instance. DBC connects to it over USB Ethernet (192.168.7.1:6379).

Power States

The scooter has two state machines: vehicle state (operational mode) and power manager state (power/suspend).

Vehicle States

stateDiagram-v2
    state "stand-by" as stand_by
    state "ready-to-drive" as ready_to_drive
    state "shutting-down" as shutting_down
    [*] --> stand_by: Boot
    stand_by --> ready_to_drive: Unlock (conditions met)
    stand_by --> parked: Unlock (kickstand down)
    ready_to_drive --> parked: Kickstand down (1s)
    parked --> ready_to_drive: Kickstand up + ready
    parked --> shutting_down: Lock
    shutting_down --> stand_by: ~5s

Ready-to-drive requires: dashboard ready, kickstand up, seatbox closed, handlebar unlocked.

Power Manager States

stateDiagram-v2
    state "suspending-imminent" as suspending_imminent
    state "hibernating-imminent" as hibernating_imminent
    [*] --> booting
    booting --> running: ~5s
    running --> suspending_imminent: Suspend request
    suspending_imminent --> suspending: ~60s delay
    suspending_imminent --> running: Abort
    suspending --> running: Wake
    suspending --> hibernating_imminent: Low battery / manual
    hibernating_imminent --> hibernating: ~20s
    hibernating --> booting: Wake (brakes 10s / BLE)

Wake from hibernation: hold both brakes 10s, or BLE connection. Keycard does not wake from hibernate.

OTA Updates

Updates are managed by update-service using Mender for atomic A/B partition updates.

  • Delta updates - Only download changed bytes
  • Channels - stable, testing, nightly
  • Independent updates - MDB and DBC update separately

Services Reference →