5.2.3 LED Strip Control

The chest LED strip control interface provides enhanced visual interaction capabilities.

Key Features

  • Independent RGB component control

  • Multiple display modes supported

LED Strip Control Service

Service Name

Data Type

Description

/aimdk_5Fmsgs/srv/SetPmuLed

SetPmuLed

LED Strip Control

Attention

The LED strip service responds slowly; expect ~5 seconds for a full call. For multitasking, run this service in a separate thread or use asynchronous calls.

Caution

As standard ROS DO NOT handle cross-host service (request-response) well, please refer to SDK examples to use open interfaces in a robust way (with protection mechanisms e.g. exception safety and retransmission)

While the robot is in Stable Standing Mode or Locomotion Mode, DO NOT launch ROS nodes in rapid bulk (no more than 2 nodes per second is recommended), as a large number of nodes joining DDS discovery within a short period causes communication congestion and degrades motion control real-time performance, which may cause the robot to lose balance and fall

  • SetPmuLed ros2-srv @ hal/srv/SetPmuLed.srv

    # LED Strip Control
# Service: /aimdk_5Fmsgs/srv/SetPmuLed

# Request
CommonRequest request  # Request header
string trace_id        # Source trace ID

uint8 led_strip_mode  # LED mode (0: steady, 1: breathing, 2: blinking, 3: flowing)
uint8 r  # Red component, 0–255
uint8 g  # Green component, 0–255
uint8 b  # Blue component, 0–255

int32 priority        # Priority (higher value = higher priority, initial threshold is 0)
bool reset_priority   # When true, resets the threshold to 0

---

# Response
ResponseHeader header  # Response header
uint16 status_code  # Status code (0: success, 0x1024: insufficient priority, others: failure)

    led_strip_mode description:

    Value

    Mode

    Description

    0

    Steady

    1

    Breathing

    4-second cycle, sinusoidal brightness transition

    2

    Blinking

    1-second cycle, toggles every 0.5s

    3

    Flowing

    2-second cycle, lights move left → right, then turn off simultaneously

    ≥4

    Invalid

    Unsupported mode value; the request will be rejected

Priority Mechanism

  • The system maintains a priority threshold (initially 0). A new request is accepted only when its priority is greater than or equal to the threshold, and the threshold is then updated to that value.

  • When priority is lower than the threshold, the request is rejected and returns status_code = 0x1024.

  • reset_priority = true means forced preemption: skips the priority check, resets the threshold to 0, and executes the request (the priority field is ignored and does not update the threshold). This is intended for urgent scenarios (e.g. when task_manager needs to forcibly take over the LED strip during faults or boot).

Attention

Avoiding LED strip control conflicts:

At runtime, the task_manager module automatically controls the LED strip during boot, state transitions, and fault diagnosis, which may override user settings. To retain persistent control of the LED strip, run the following command on the Motion Control Computing Unit (PC1) to stop the task_manager module:

aima em stop-app task_manager

If task_manager is not stopped, users can still call SetPmuLed, but note the following:

  • User LED strip settings may be forcibly preempted at any time by task_manager’s automatic control (task_manager uses reset_priority=true to skip the priority check and override directly).

  • Subscribe to the /aima/hal/pmu/led_state topic to monitor LED strip state changes and re-apply settings after an override.

LED Strip State Topic

Topic Name

Data Type

Description

QoS

Frequency

/aima/hal/pmu/led_state

PmuLedState

Current LED strip state

BEST_EFFORT+TRANSIENT_LOCAL

1Hz

  • PmuLedState ros2-msg @ hal/msg/PmuLedState.msg

    # PMU LED strip state
MessageHeader header             # Message header (not enabled; see note below)
string trace_id                  # Source trace
uint8 led_strip_mode             # LED strip mode (0 (LED_STRIP_MODE_CONSTANT constant), 1 (LED_STRIP_MODE_BREATH breath), 2 (LED_STRIP_MODE_FLASH flash), 3 (LED_STRIP_MODE_FLOW flow))
uint8 r                          # Red component 0-255
uint8 g                          # Green component 0-255
uint8 b                          # Blue component 0-255
int32 priority                   # Currently effective priority

Note

led_state field usage notes:

  • header: The MessageHeader field is currently not filled (stamp/frame_id/sequence are all default zero values); do not use it for time synchronization.

  • Semantics: This topic publishes the parameter values from the most recent SetPmuLed request that passed the priority check, not the actual hardware state read back from the LED. Requests rejected due to insufficient priority (returns 0x1024) do not update mode/r/g/b; requests whose SDK call fails still update the values.

Programming Examples

For detailed programming samples and explanations, refer to: