Signal Generator Example

Example demonstrating bidirectional communication with automatic parameter updates.

Overview

The signal_generator example shows:

Input and output reports
Command interface usage
Automatic parameter cycling
Bidirectional data flow

Schema

Features both input and output reports:

device_name: "Signal Generator"
vendor_id: "0xCAFE"
product_id: "0x4000"

input_report_id: 2   # Device → PC
output_report_id: 1  # PC → Device

sensor_name: "signal_gen"
gpio_name: "signal_params"
frame_id: "signal_gen_frame"
update_rate: 250
publish_rate: 100.0

# Input fields (device sends to PC)
inputs:
  - name: "timestamp"
    type: "float32"
  - name: "result"
    type: "float32"

# Output fields (PC sends to device)
outputs:
  - name: "amplitude"
    type: "float32"
  - name: "frequency"
    type: "float32"
  - name: "phase"
    type: "float32"

How It Works

The signal generator demonstrates bidirectional communication:

Device (firmware) receives parameters (amplitude, frequency, phase) via output report
Device computes: result = amplitude * sin(frequency * t + phase)
Device sends result via input report
Controller automatically cycles through different parameter combinations every 10 seconds
Controller publishes current parameters to ~/current_params topic

Building

colcon build --packages-select signal_command_controller signal_generator_bringup

Running

ros2 launch signal_generator_bringup signal_gen.launch.py

Monitoring

Monitor Generated Signal

# Watch the signal output from device
ros2 topic echo /signal_gen_broadcaster/signal_gen_states

Monitor Current Parameters

# Watch the parameters being sent to device
ros2 topic echo /signal_command_controller/current_params

The controller automatically cycles through parameter combinations:

Amplitude: 0.5, 1.0, 1.5, 2.0
Frequency: 0.5, 1.0, 2.0, 3.0 Hz
Phase: 0, π/4, π/2, π

Parameters update every 10 seconds (configurable via update_interval parameter).

Source Code

See the example package for implementation.