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librescoot-battery (battery-service)

Description

The battery service monitors the two main battery slots (battery:0 and battery:1) via NFC readers. Each battery has an NFC tag that provides battery management data including state, charge level, cycle count, and fault codes. The service communicates with batteries through NFC when they are inserted and active.

Command-Line Options

Usage of battery-service:
  -battery1-active
        Enable battery 1 as active in addition to battery 0 (default: inactive)
  -keep-active-on-seatbox-open
        Keep a running battery active across seatbox open, but let seatbox events flow normally so asleep batteries go through the wake-up cycle and newly inserted batteries are detected without delay
  -debug
        Enable debug logging for detailed NCI/DATA messages
  -device0 string
        Battery 0 NFC device (default "/dev/pn5xx_i2c0")
  -device1 string
        Battery 1 NFC device (default "/dev/pn5xx_i2c1")
  -disable-battery1
        Disable battery 1 reader entirely
  -heartbeat-timeout uint
        Heartbeat timeout for standby mode in seconds (default 40)
  -log int
        Service log level (0=NONE, 1=ERROR, 2=WARN, 3=INFO, 4=DEBUG) (default 3)
  -log0 int
        Battery 0 log level (0=NONE, 1=ERROR, 2=WARN, 3=INFO, 4=DEBUG) (default 3)
  -log1 int
        Battery 1 log level (0=NONE, 1=ERROR, 2=WARN, 3=INFO, 4=DEBUG) (default 3)
  -off-update-time uint
        Update time when disabled in seconds (30 minutes) (default 1800)
  -redis-port uint
        Redis server port (default 6379)
  -redis-server string
        Redis server address (default "127.0.0.1")
  -version
        Show version information

Redis Operations

Hash: battery:0 and battery:1

Fields written:

  • state - Battery state ("unknown", "asleep", "idle", "active")
  • present - Battery presence ("true" or "false")
  • charge - State of charge percentage (0-100)
  • cycle-count - Battery cycle count
  • temperature:0 - Battery temperature sensor 0 (°C)
  • temperature:1 - Battery temperature sensor 1 (°C)
  • temperature:2 - Battery temperature sensor 2 (°C)
  • temperature:3 - Battery temperature sensor 3 (°C)
  • temperature-state - Temperature status ("unknown", "cold", "hot", "ideal")
  • current - Battery current (mA)
  • voltage - Battery voltage (mV)
  • state-of-health - Battery health percentage (0-100)
  • serial-number - Battery serial number
  • manufacturing-date - Manufacturing date
  • fw-version - Firmware version

Published channels and messages:

  • battery:0, battery:1 - Battery state change notifications
  • present - Battery presence changed
  • state - Battery state changed
  • charge - Charge level changed
  • temperature-state - Temperature state changed
  • fault - Fault status changed

Hash: settings

Fields read:

  • scooter.battery-keep-active-on-seatbox-open - Bool (true/false); runtime equivalent of the -keep-active-on-seatbox-open CLI flag. Keeps a running battery active across a seatbox open while still letting seatbox events flow. Hot-reloaded via settings pub/sub; a change restarts any mid-cycle active reader so the new value takes effect at once.
  • scooter.dual-battery - Bool (true/false); controls whether battery slot 1 is treated as active/present. true sets reader 1 to the active role (subject to the scooter.max-voltage-delta check); false sets it inactive (disabled). Read on startup and hot-reloaded via settings pub/sub; only takes effect when a slot 1 reader exists.
  • scooter.max-voltage-delta - Max voltage difference between batteries in mV before battery 1 activation is refused (default: 1000; 0 to disable). Updated live via settings pub/sub.
  • scooter.battery-aux-low-keep-active-enter-mv - Aux battery voltage in mV below which the keep-active-on-seatbox-open override engages automatically (default: 11500). Hot-reloaded via settings pub/sub.
  • scooter.battery-aux-low-keep-active-exit-mv - Aux battery voltage in mV at or above which the aux-low keep-active override disengages (default: 12000). Must be greater than the enter threshold. Hot-reloaded via settings pub/sub.

Hash: aux-battery

Fields read:

  • voltage - Auxiliary (12 V) battery voltage in mV; consumed to drive the aux-low keep-active override.

Subscribed channels:

  • aux-battery - Aux battery field change notifications
  • voltage - Recomputes the keep-active-on-seatbox-open override using Schmitt-trigger hysteresis (engages when below the enter threshold, disengages when at or above the exit threshold). On a transition, active readers are restarted so the FSM walks through the wake-up sequence.

Hash: vehicle

Fields read:

  • state - Vehicle state (monitored to adjust battery behavior)
  • seatbox:lock - Seatbox lock state ("closed" or "open")

Subscribed channels:

  • vehicle - Vehicle state change notifications
  • state - Vehicle state changed
  • seatbox:lock - Seatbox lock state changed

Sets: battery:0:fault and battery:1:fault

Fault codes stored as set members:

  • Hardware faults (1-16): Temperature, voltage, current protection faults
  • Software faults (32+): Communication errors, NFC reader errors

Stream: events:faults

Fault events written:

  • group - Source (e.g., "battery:0")
  • code - Fault code (positive for set, negative for cleared)
  • description - Human-readable fault description

Hardware Interfaces

NFC Readers

  • Device 0: /dev/pn5xx_i2c0 (default, configurable via --device0)
  • Device 1: /dev/pn5xx_i2c1 (default, configurable via --device1)
  • Chip: PN7150 NFC controller (I2C interface)

Each battery slot has a dedicated NFC reader to communicate with the battery's NFC tag.

Battery Communication Protocol

The service uses NFC Type 4 Tag operations to communicate with battery NFC tags:

Read Operations:

  • 0x0300 - STATUS0: Voltage, current, firmware version, remaining/full capacity, fault code, temperatures 0-1, state of health, low SOC flag
  • 0x0310 - STATUS1: Battery state (4 bytes), serial number (12 bytes)
  • 0x0320 - STATUS2: Serial number continuation (4 bytes), manufacturing date (8 bytes), cycle count (2 bytes), temperatures 2-3

Write Operations:

  • 0x0330 - COMMAND: 4-byte command code to control battery state

Battery Commands:

  • BMSCmdOn (0x50505050) - Enable high-current path
  • BMSCmdOff (0xCAFEF00D) - Disable high-current path
  • BMSCmdInsertedInScooter (0x44414E41) - Battery inserted notification
  • BMSCmdSeatboxOpened (0x48525259) - Seatbox opened notification
  • BMSCmdSeatboxClosed (0x4D4B4D4B) - Seatbox closed notification
  • BMSCmdHeartbeatScooter (0x534E4A41) - Keep-alive heartbeat

Battery States:

  • BMSStateUnknown (0x00000000) - Cannot determine state
  • BMSStateAsleep (0xA4983474) - Lowest power mode
  • BMSStateIdle (0xB9164828) - Systems on, high-current path disabled
  • BMSStateActive (0xC6583518) - High-current path enabled

Configuration

Systemd Unit

  • Unit file: /usr/lib/systemd/system/battery-service.service
  • Started by: systemd at boot
  • Restart policy: Always

Observable Behavior

Startup Sequence

  1. Opens NFC device interfaces for both battery slots
  2. Connects to Redis
  3. Initializes NFC readers (PN7150 chips)
  4. Starts periodic battery polling
  5. Publishes initial battery state

Runtime Behavior

When Battery Inserted

  1. NFC tag detected
  2. Battery woken from sleep (if asleep)
  3. Battery parameters read via NFC
  4. State published to Redis battery:N hash
  5. Publishes to battery:N channel

Polling Intervals

  • Active mode (non-standby): 10 seconds between status updates
  • Active mode (standby): 40 seconds between status updates (configurable via --heartbeat-timeout)
  • Inactive mode: 30 minutes between status updates (configurable via --off-update-time)
  • Tag discovery (seatbox open): 100ms polling interval for fast detection
  • Tag discovery (seatbox closed): 2500ms polling interval for power efficiency

Battery States

  • unknown: Cannot determine battery state
  • asleep: Battery in lowest power mode
  • idle: Battery systems on, high-current path disabled
  • active: High-current path enabled, ready for driving/charging

State transitions are triggered by:

  • Vehicle state changes (monitored via vehicle hash and channel)
  • Seatbox lock state changes (monitored via vehicle hash and channel)
  • Battery role (active/inactive) and enabled state
  • Battery internal conditions (SOC, faults)
  • NFC communication status

Battery Control

Battery behavior is controlled by:

  1. Battery Role:
  2. active - Can provide power (battery 0 is always active)
  3. inactive - Cannot provide power (battery 1 by default, use --battery1-active to make active)

Voltage delta protection: Battery 1 activation is refused if the voltage difference between both batteries exceeds scooter.max-voltage-delta (default: 1000 mV). Checked on startup, on setting change, and on battery swap; clears when a compatible battery is inserted.

  1. Enabled State (for active batteries):
  2. Automatically controlled based on seatbox lock state
  3. When seatbox closed: battery enabled

  4. When seatbox open: battery disabled (unless -keep-active-on-seatbox-open is set, or it auto-engages when the aux battery is low)

  5. Battery State Machine:

  6. Service sends appropriate commands (on/off) based on enabled state
  7. Monitors battery compliance with commands
  8. Raises BMSFaultBMSNotFollowingCmd if battery doesn't respond correctly

State Machine

Each battery reader implements a hierarchical state machine:

Top-level states:

  • StateInit - Waiting for initial vehicle/seatbox state from Redis
  • StateNFCReaderOff - NFC reader deinitialized (during recovery)
  • StateNFCReaderOn - NFC reader initialized and operational

Discovery states (under NFCReaderOn):

  • StateDiscoverTag - Parent state for tag discovery
  • StateWaitArrival - Actively polling for tag arrival
  • StateTagAbsent - No tag detected, periodic checking

Tag present states (under NFCReaderOn):

  • StateTagPresent - Parent state when battery inserted
  • StateCheckPresence - Verifying battery responds to commands
  • StateWaitLastCmd - Waiting for minimum time between commands (400ms)
  • Seatbox open path:
    • StateSendOff - Sending OFF command
    • StateSendOpened - Sending SEATBOX_OPENED command
    • StateSendInsertedOpen - Sending INSERTED_IN_SCOOTER command
  • Seatbox closed path (heartbeat):
    • StateHeartbeat - Setting up heartbeat timer
    • StateHeartbeatActions - Performing heartbeat sequence
    • StateSendClosed - Sending SEATBOX_CLOSED command
    • StateSendOnOff - Sending ON or OFF command based on enabled state
    • StateCondStateOK - Checking if battery state matches expected
    • StateWaitUpdate - Waiting for next heartbeat interval
    • StateSendInsertedClosed - Sending INSERTED_IN_SCOOTER for recovery

State machine features:

  • Event-driven transitions (tag events, timeouts, vehicle state changes)
  • Hierarchical states with parent-child relationships
  • Automatic recovery from communication failures
  • Suspend inhibitor management during critical operations
  • Discovery polling rate adapts to seatbox state

Error Recovery

The service implements multiple recovery mechanisms:

  1. NFC Read Verification:
  2. Double-read all battery data
  3. Compare reads to detect corruption

  4. Retry up to 4 times on mismatch

  5. Arbiter Busy Recovery:

  6. Detect NFC arbiter busy condition
  7. Call SelectTag(0) to reset arbiter

  8. Retry operation

  9. Communication Failure Recovery:

  10. Track consecutive communication failures
  11. After failures, transition to StateNFCReaderOff
  12. Deinitialize NFC reader
  13. Wait 2 seconds
  14. Full reinitialization with power cycle

  15. Resume normal operation

  16. Zero Data Recovery:

  17. Detect when battery returns all-zero data
  18. Increment recovery counter
  19. Retry up to 10 times with heartbeat

  20. After threshold, enter passive discovery (long polling intervals)

  21. Heartbeat Timeout Recovery:

  22. Monitor battery state compliance
  23. If state incorrect after timeout, force tag rediscovery

  24. Prevents endless stuck states

  25. Cold Boot Recovery:

  26. Detect PN7150 cold boot semantic errors (status 0x06)
  27. Automatically reinitialize reader
  28. Resume discovery

Fault Detection and Reporting

The service monitors for battery faults using a debounced fault management system:

Hardware Faults (from BMS):

  1. ChgTempOverHighProt - High temperature during charging
  2. ChgTempOverLowProt - Low temperature during charging
  3. DsgTempOverHighProt - High temperature during discharge
  4. DsgTempOverLowProt - Low temperature during discharge
  5. SignalWireBrokeProt - Signal wire disconnected
  6. SecondLvlOverTemp - Critical temperature level
  7. PackVoltHighProt - Battery pack overvoltage
  8. MosTempOverHighProt - Power transistor overheating
  9. CellVoltHighProt - Cell overvoltage
  10. PackVoltLowProt - Battery pack undervoltage
  11. CellVoltLowProt - Cell undervoltage
  12. CrgOverCurrentProt - Charging overcurrent
  13. DsgOverCurrentProt - Discharge overcurrent
  14. ShortCircuitProt - Short circuit detected

Software Faults (detected by service):

  • BMSNotFollowingCmd (32) - Battery not responding to commands (5s set debounce, 10s reset debounce)
  • BMSZeroData (33) - Battery data unavailable (critical, immediate)
  • BMSCommsError (34) - Battery communication failed (critical, 5s set debounce, 10s reset debounce)
  • NFCReaderError (35) - NFC reader malfunction (critical, 30s set debounce)

Fault Reporting:

  • Faults stored in Redis sets: battery:N:fault
  • Fault events logged to Redis stream: events:faults
  • Fault changes published to battery:N channel with message "fault"
  • Critical faults cause battery to report as not present

Log Output

The service logs to journald with leveled logging:

Log Levels:

  • 0 = NONE - No logs
  • 1 = ERROR - Only error messages
  • 2 = WARN - Warning messages and errors
  • 3 = INFO - Informational messages (default)
  • 4 = DEBUG - Detailed debug messages

Configuration:

  • --log - Service-wide log level (default: 3)
  • --log0 - Battery 0 reader log level (defaults to --log)
  • --log1 - Battery 1 reader log level (defaults to --log)
  • --debug - Enable detailed NCI/DATA messages from NFC HAL

Common log messages:

  • NFC communication errors and recovery
  • Battery state transitions
  • Fault activation and clearing
  • Tag arrival/departure events
  • State machine transitions (debug level)
  • NCI protocol messages (debug mode only)

Viewing logs: 

journalctl -u battery-service -f           # Follow logs
journalctl -u battery-service --since today # Today's logs

Dependencies

  • Go runtime - CGO_ENABLED=0 for static binary compilation
  • PN7150 NFC readers - Must be accessible via I2C at /dev/pn5xx_i2c0 and /dev/pn5xx_i2c1
  • Redis server - Must be running at specified host:port (default: 127.0.0.1:6379)
  • Battery NFC tags - Batteries must have functional NFC Type 4 tags
  • pm-service - Holds a block inhibitor via pm-service's /tmp/suspend_inhibitor socket during NFC transactions, so the MDB does not suspend/hibernate mid-write.
  • Linux kernel - I2C support and device nodes

Go Dependencies:

  • github.com/redis/go-redis/v9 - Redis client
  • golang.org/x/sys - System calls for I2C and systemd integration

Librescoot Implementation

The Librescoot battery-service is a complete Go reimplementation with architectural improvements:

Key Features

  • Per-battery log levels: Separate --log0 and --log1 flags for independent log control
  • Service-wide log level: Global --log flag with per-battery override capability
  • Build-time information: Git revision and build time embedded in binary (--version)
  • Enhanced NFC error handling: Robust recovery from I2C errors and NFC reader failures
  • Temperature state management: Four-state temperature monitoring (unknown/cold/hot/ideal)
  • Debounced fault management: Prevents fault flapping with configurable debounce times
  • Suspend inhibitor integration: Blocks system suspend during critical NFC transactions
  • Dual battery support: Independent control of two battery slots with configurable roles
  • Seatbox safety: Automatic battery disable when seatbox opens (unless overridden)

Architecture Improvements

  • Goroutine-based concurrency: Each battery reader runs in its own goroutine with independent state machine
  • Event-driven design: Tag arrival/departure events, vehicle state changes, seatbox updates processed asynchronously
  • Clean NFC HAL: Hardware abstraction layer for PN7150 with error classification (transient vs. fatal)
  • Read verification: Double-read verification for critical data to prevent corruption
  • Arbiter busy handling: Automatic retry with tag reselection on NFC arbiter conflicts
  • Heartbeat monitoring: Configurable heartbeat timeouts with automatic recovery
  • State machine recovery: Automatic NFC reader reinitialization on communication failures
  • Redis transactions: Atomic updates to battery hashes with pipelined operations

Building

# Build for ARM target (ARMv7)
make build                  # Output: bin/battery-service

# Build for AMD64 (development/testing)
make build-amd64           # Output: bin/battery-service-amd64

# Build for current platform
make build-native

# Development build (with debug symbols)
make dev-build

# Clean build artifacts
make clean

Build system:

  • Static linking (-extldflags '-static')
  • Version information embedded via linker flags
  • Cross-compilation support for ARM and AMD64
  • Minimal dependencies (CGO_ENABLED=0)

Compatibility

Librescoot battery-service maintains full Redis compatibility with original firmware:

Compatible interfaces:

  • Same hash fields in battery:0 and battery:1
  • Same channel publication patterns
  • Same fault reporting mechanisms
  • Same vehicle state monitoring

Behavioral improvements:

  • More robust error recovery
  • Better fault classification
  • Enhanced logging
  • Configurable timeouts

Not a drop-in replacement for:

  • Command-line options changed (original used different flag names)
  • No battery:N:power list consumption (control is internal based on vehicle/seatbox state)