Skip to content

BaseBoard Boot-up & Network Watchdog

Boot-up Sequence & Timings

Defines the hardware initialization of BaseBoard and the FreeRTOS thread startup sequence, specifying the golden time when the PC can start UDP communication.

Initialization Flow

  1. Entry Point: main() → FreeRTOS scheduler starts → app_main() thread creation
  2. System Init thread: Actual I/O and network stack(lwIP) initialization proceeds sequentially in a separate system_init thread
  3. Boot Done: When all initialization succeeds, it switches to bootDone = true and periodic data publishing begins

Key Wait Times and Availability Points

  • Initialization wait times vary depending on the board revision.
  • PC communication start condition: Even if the UDP socket(T_SOCKET) is open, the firmware can only confirm the counterpart's IP address and send a response after receiving at least one packet from the PC.
Stage Main Tasks Accumulated Wait Time(min) Remarks
T0 Power On and Kernel Start 0s Run LED fast blinking
T1 HW Initialization and Stabilization Approximately 6~10s I2C, SPI, IMU, Audio Initialization
T2 Ethernet PHY Reset/Stabilization Approximately 12~16s Includes fixed 6s wait
T_SOCKET Open UDP Receive Socket Approximately 15~20s PING reception possible from this point
T_BOOT Initialization Complete(Boot Done) Approximately 20~30s Start periodic Topic publishing

Available Functions by FW Status Section

  • Command processing is possible between T_SOCKET and T_BOOT, but periodic Publish is not yet available.
  • Recommended PC-side behavior: Immediately after power-on, PING may be dropped for up to 20 seconds. Implement a retry logic and keep trying until the first ECHO response is received.
Section UDP Reception Command Processing(PING/SHUTDOWN/ESTOP etc.) Periodic Publish(IVT/GenericStatus etc.)
T0 ~ T_SOCKET X (packet drop) X X
T_SOCKET ~ T_BOOT ✓ ✓ X
After T_BOOT ✓ ✓ ✓

UDP Port & Packet

Port Map

All ports are based on the offset from PORT_BASE = 49152. IN/OUT is based on the BaseBoard.

Name Value Direction Usage
MAIN_COMS_IN_PORT 49158(PORT_BASE + 6) PC → FW Command Reception (COMS_CMD_*)
MAIN_COMS_OUT_PORT 49157(PORT_BASE + 5) FW → PC Status Packet / PING ECHO

PING/ECHO Packet Structure

Direction Type Size Payload
PC → FW MAIN_COMS_PACKET 12 B NetPacketHeader(4) + COMS_CMD cmd(4) + COMS_ARG arg(4)
FW → PC PING_ECHO_PACKET 12 B MAIN_COMS_PACKET_HEADER(8) + uint32_t seq_num(4)

  • PC → FW

    • cmd = COMS_CMD_PING
    • arg = sequence number.

  • FW → PC

    • type = MC_PACKET_TYPE_PING_ECHO
    • seq_num reflects the arg exactly as received.

Peer Discovery

The FW has no fixed target IP and undergoes the following dynamic learning process:

  1. First reception: Immediately upon receiving the first packet sent by the PC(e.g., PING), it learns the counterpart's IP.
  2. Target confirmation: Subsequently, the destination address of all Out-Stream(IMU, BMS, etc.) is uniformly updated to that IP.
  3. WOL(Wake On Lan) preparation: Stores the counterpart's MAC address through ARP(Address Resolution Protocol) query.

Heartbeat(Ping) & Network Watchdog

A mechanism that mutually monitors connection status(heartbeat) and performs self-recovery (watchdog) in case of failure.

Heartbeat Mechanism

  • PC → FW: Periodically send COMS_CMD_PING packets(recommended interval: 1Hz, maximum less than 2.5s).
  • FW → PC: Immediately respond with MC_PACKET_TYPE_PING_ECHO. At the same time, call internal NetworkWatchdog::Feed() to reset the watchdog timer.

Network Watchdog Configuration

Constant Value Meaning
kProbeIntervalMs 2500 ms Time of PING no response detection = ICMP probe start reference
kRetryIntervalMs 1000 ms Retry interval on ICMP failure
kMaxProbeFails 2 Allowed number of consecutive ICMP failures(initial probe + 2 retries = total 3 times)
kMaxRecoveries 5 Maximum number of PHY resets
kPhyResetLeadTimeMs 6000 ms Stabilization wait after PHY reset
PING_RCV_TIMEO 500 ms lwIP ping receive timeout

Recovery Scenario

Situation Action and Judgment Measure
Normal PING Received within 2.5 seconds Watchdog Feed → Timer Reset
No PING Response No response exceeding 2.5 seconds FW directly sends ICMP Echo(Ping) to PC
ICMP Success PC response confirmed Judged as connection maintained(Log: "Probe success") → Timer restart
ICMP Failure Retry every 1 second(initial + 2 retries = total 3 attempts) If all fail, enter hardware recovery stage
Network Recovery After 3 consecutive failures, Ethernet PHY hardware reset then wait 6 seconds → retry Up to 5 attempts for reset
Recovery Abandonment PHY reset failed 5 times Probe permanently stopped(PauseUntilFeed). Automatically restarts with Feed() when PC sends PING again

Graceful Shutdown(Shutdown Logic)

When the user presses the power button to attempt shutdown, the FW does not just cut the power but checks the PC's shutdown status.

  1. If main_coms.IsConnected() is true(meaning there has been communication with the PC at least once before), replace the Watchdog handler with GracefulShutdownHandler.
  2. Send ICMP probes at 1-second intervals.
  3. If there is no response for 10 consecutive times(10 seconds), consider the PC fully shut down and cut the baseboard power.
  4. If the PC responds before that or sends COMS_CMD_SHUTDOWN, immediately proceed with the shutdown routine.