Ex: SDL Command

Reconfigure a Carbon sensor at runtime with C++.

This example demonstrates how to send a Software Defined LiDAR (SDL) command to a Carbon sensor. SDL commands change the sensor’s operating state, field of view, frame rate, and waveform parameters at runtime — no restart required.

What You’ll Learn

• How to build an SdlCommandParams from the current sensor state
• How to apply settings with the recommended blocking path (sendSdlBlocking)
• How the non-blocking sendSdl / pollSdl path fits an event loop

Prerequisites

• Voyant SDK installed (see Installation)
• A Carbon sensor, or the bundled carbon_simulator running locally (pass --sim)

Example Code

View the complete example on GitHub: sdl_command.cpp

Key Concepts

Building the Command

Wait for a heartbeat, then build the command from the sensor’s current read-back with toSdlCommand() and override only the fields you want to change:

SdlCommandParams cmd   = toSdlCommand(state);
cmd.req_state          = static_cast<uint8_t>(SdlState::PointCloud);
cmd.hfov_deg           = 60.0f;
cmd.hfov_center_deg    = 0.0f;   // steering not yet supported — keep at 0
cmd.frame_rate_fps     = 10.0f;
cmd.ramp_bandwidth_ghz = 6.0f;
// ramp_length is firmware-fixed (16.384 µs) and read-back only; the build ignores it.

Applying It (Blocking)

sendSdlBlocking() sends the command and waits for the sensor to confirm. It returns an SdlStatus — SdlStatus::Applied on success:

SdlStatus status = client.sendSdlBlocking(cmd);
if (status != SdlStatus::Applied)
{
    std::cerr << "SDL command failed: SdlStatus(" << static_cast<int>(status) << ")" << std::endl;
    return 1;
}

Non-blocking Alternative

For event loops that must keep processing frames while a command is in flight, sendSdl() starts the command and pollSdl() drives it to completion. Poll until the status is no longer SdlStatus::Pending. The blocking path is recommended for normal use.

Building and Running

# Build the examples
mkdir build && cd build
cmake ..
make

# Run against a real sensor
./bin/sdl_command

# Or run against a local carbon_simulator
./bin/sdl_command --sim

Expected Output

Sending SDL command...
SDL command applied successfully.
Frame 1: Header{message type:2, device id:CAR-000, frame idx:41, ...}
Frame 2: Header{message type:2, device id:CAR-000, frame idx:42, ...}
...

Next Steps

• Live Client — inspect the frames your new configuration produces
• API Documentation — full CarbonClient and SDL reference