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ipro_le_audio_headset

LE Audio unicast headset: BAP unicast server, PACS, ASCS, CAP, CSIP, VCP, with LC3 decoded to the DAC. Tutorial: Getting Started with LE Audio

Item Details
Source apps/bluetooth/le_audio/ipro_le_audio_headset
Boards and configs Reef (defconfig_reef: DAC output to the headset jack and speaker); .config, DAC.config and UAC.config target the IPRO7 EVB
Console UART 115200
Build Reef: make -C apps/bluetooth/le_audio/ipro_le_audio_headset DEFCONFIG=defconfig_reef

Run it on the Reef

  1. Build

    make -C apps/bluetooth/le_audio/ipro_le_audio_headset DEFCONFIG=defconfig_reef

    The image is apps/bluetooth/le_audio/ipro_le_audio_headset/build_reef/build_out/ipro_le_audio_headset_IPRO7.bin.

  2. Flash: enter download mode, then from the IntelProCube directory run

    ./ipro_iot_tool_macos --chipname ipro7 --chip-variant IPRO7AI \
    --port /dev/cu.usbserial-XXXX --baudrate 921600 \
    --firmware <SDK>/apps/bluetooth/le_audio/ipro_le_audio_headset/build_reef/build_out/ipro_le_audio_headset_IPRO7.bin

    Check for [All Success], then press SW2.

  3. Run: open the console at 115200 baud. The board advertises as IPRO-LE-Audio; pair it from an LE Audio phone (numeric comparison is confirmed on the board automatically). leaudio_status at the console shows the connection and stream state. SW3, SW4 and SW5 are volume down, volume up and mute through VCP.

Status in this release

The application's README records that a phone connects, discovers the services and bonds at security level 4; media streaming from a phone is not validated yet.

README

The README as shipped

Below is the README that ships with the application (SDK V2.2.1), as written; only content unfit for publication was replaced.

Overview

LE Audio Unicast Headset bring-up application for the new IPRO BLE controller component and unified Zephyr-derived host.

Current validated status is profile/HCI ISO payload bring-up, not a finished customer audio product:

  • peripheral advertising as IPRO-LE-Audio
  • SMP/settings/bonding enabled
  • BAP unicast server, PACS, ASCS, CAS and VCP Volume Renderer enabled
  • CIS setup and ISO RX payload path validated with the two-board central test
  • UART shell enabled at 115200
  • controller config: link1_periph, feature profile bt54_iso2, EM 32 KiB
  • audio output/render is currently disabled; LC3 decode/render and acoustic validation remain open

The two-board automated peer used for this validation (ipro_ble_controller_central_test) is an internal test app and is not part of the SDK package; any LE Audio unicast client can act as the peer.

Android phone basic status:

  • Pixel 10 Pro / Android 17 can scan/connect to IPRO-LE-Audio.
  • Android GATT service discovery has found 1801,1853,1850,184e,1844.
  • Android system Bluetooth reports LE Audio connected and Volume Control connected.
  • Actual LE Audio media streaming is not yet validated; Android currently reports zero connected audio channels with this firmware.

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                    PC/Smartphone (LE Audio Source)              │
│                                                                   │
│  ┌──────────────┐   ┌──────────────┐   ┌──────────────┐        │
│  │  Music App   │   │ Volume Ctrl  │   │ Media Ctrl   │        │
│  └──────┬───────┘   └──────┬───────┘   └──────┬───────┘        │
│         │                  │                   │                 │
│         ▼                  ▼                   ▼                 │
│  ┌────────────────────────────────────────────────────┐         │
│  │         BLE LE Audio Unicast Client (CAP)          │         │
│  │  ┌──────────┐  ┌──────────┐  ┌──────────┐         │         │
│  │  │   BAP    │  │   VCP    │  │   MCP    │         │         │
│  │  └──────────┘  └──────────┘  └──────────┘         │         │
│  └────────────────────────────────────────────────────┘         │
└───────────────────────────────┬─────────────────────────────────┘
                                │ BLE Link (CIS)
                                │ LC3 Encoded Audio
                                ▼
┌─────────────────────────────────────────────────────────────────┐
│              IPRO7 LE Audio Unicast Headset                     │
│                                                                   │
│  ┌────────────────────────────────────────────────────────┐     │
│  │              BLE LE Audio Server Stack                 │     │
│  │  ┌──────────┐  ┌──────────┐  ┌──────────┐  ┌──────┐  │     │
│  │  │ BAP      │  │ VCP      │  │ MCP      │  │ CCP  │  │     │
│  │  │ Unicast  │  │ Server   │  │ Server   │  │      │  │     │
│  │  │ Server   │  │          │  │          │  │      │  │     │
│  │  └────┬─────┘  └────┬─────┘  └────┬─────┘  └──────┘  │     │
│  └───────┼─────────────┼─────────────┼───────────────────┘     │
│          │             │             │                           │
│  ┌───────▼─────────────▼─────────────▼───────────────────┐     │
│  │         GAF (Generic Audio Framework)                  │     │
│  └────────────────────────┬───────────────────────────────┘     │
│                           │                                      │
│  ┌────────────────────────▼───────────────────────────────┐     │
│  │              Audio Data Path                           │     │
│  │  ┌──────────┐  ┌──────────┐  ┌──────────┐             │     │
│  │  │ ISOOHCI  │→ │   LC3    │→ │   Ring   │             │     │
│  │  │ Receive  │  │ Decoder  │  │  Buffer  │             │     │
│  │  └──────────┘  └──────────┘  └────┬─────┘             │     │
│  │                                    │                    │     │
│  │  ┌──────────┐  ┌──────────┐  ┌────▼─────┐             │     │
│  │  │ ISOOHCI  │← │   LC3    │← │   Ring   │             │     │
│  │  │ Transmit │  │ Encoder  │  │  Buffer  │             │     │
│  │  └──────────┘  └──────────┘  └──────────┘             │     │
│  └────────────────────────┬───────────────────────────────┘     │
│                           │                                      │
│  ┌────────────────────────▼───────────────────────────────┐     │
│  │              USB Audio Class (UAC)                     │     │
│  │  ┌──────────────────┐      ┌──────────────────┐       │     │
│  │  │  UAC Playback    │      │  UAC Capture     │       │     │
│  │  │  (Speaker Out)   │      │  (Mic In)        │       │     │
│  │  └────────┬─────────┘      └────────▲─────────┘       │     │
│  └───────────┼──────────────────────────┼─────────────────┘     │
└──────────────┼──────────────────────────┼───────────────────────┘
               │                          │
               ▼                          │
        ┌─────────────┐          ┌───────┴──────┐
        │   Speaker   │          │  Microphone  │
        └─────────────┘          └──────────────┘

Key Features

Audio Profiles

  • BAP (Basic Audio Profile): Unicast audio streaming with CIS (Connected Isochronous Stream)
  • VCP (Volume Control Profile): Remote volume control from source device
  • MCP (media control) and CCP (call control) are not enabled in the shipped .config (no CONFIG_BT_MCC / CONFIG_BT_MCS)

Audio Capabilities

  • Codec: LC3 (Low Complexity Communications Codec)
  • Sample Rates: 16kHz, 24kHz, 32kHz, 48kHz
  • Frame Duration: 7.5ms, 10ms
  • Bitrates: 32kbps - 96kbps (configurable)
  • Bidirectional Audio: Simultaneous playback and capture

Advanced Features

  • Auto-reconnection: Automatically reconnect to paired devices
  • Battery Service: Report battery level to connected device
  • Device Information Service: Expose device info (model, firmware version)
  • GATT Caching: Faster reconnection with cached GATT database
  • Smart Power Management: Optimized for low power consumption

Shell Commands

# Volume Control
volume get                    # Get current volume
volume set <0-255>           # Set volume level
volume mute                  # Mute audio
volume unmute                # Unmute audio

# Media Control
media play                   # Start playback
media pause                  # Pause playback
media next                   # Next track
media prev                   # Previous track

# Connection Management
gap disconnect               # Disconnect from source
gap advertise <on|off>       # Control advertising

# Audio Control
audio status                 # Show audio stream status

DEMO Application Scenarios

Scenario 1: Wireless Music Listening

Use Case: Listen to music from smartphone/PC wirelessly

Setup:

  1. Power on IPRO7 headset → auto-start advertising
  2. On smartphone: Open Bluetooth settings → Connect "IPRO-Headset"
  3. Open music app → Select IPRO-Headset as audio output
  4. Play music → Audio streams via BLE LE Audio

User Experience:

  • High-quality audio with LC3 codec (better than SBC)
  • Low latency (~20-40ms)
  • Phone volume controls work seamlessly
  • Media play/pause buttons control smartphone playback

Scenario 2: Video Conference with Bidirectional Audio

Use Case: Join video conference call with microphone support

Setup:

  1. Connect IPRO7 headset to PC
  2. Join Zoom/Teams meeting
  3. Select "IPRO-Headset" for both speaker and microphone
  4. Bidirectional audio automatically established

User Experience:

  • Clear voice transmission with LC3 encoding
  • Echo cancellation enabled
  • Low latency for natural conversation
  • USB audio seamlessly bridges BLE and PC

Scenario 3: Gaming with Low-Latency Audio

Use Case: Play mobile games with minimal audio delay

Setup:

  1. Connect to gaming smartphone
  2. Launch game application
  3. Audio automatically routes to headset with optimized latency

User Experience:

  • Fast audio response (<30ms typical)
  • Synchronized audio and visual feedback
  • Volume adjustable without leaving game

Scenario 4: Smart Home Voice Assistant

Use Case: Interact with voice assistant (Siri/Google Assistant)

Setup:

  1. Connected to smartphone
  2. Trigger voice assistant with button or wake word
  3. Audio I/O handled by headset

User Experience:

  • Clear voice command capture
  • Assistant responses play through headset
  • Hands-free operation

Build Instructions

Prerequisites

  • IPRO SDK properly set up
  • RISC-V toolchain installed (/opt/toolchain/riscv_ipro7/)

Build Command

cd <SDK root>
PATH=/opt/toolchain/riscv_ipro7/bin:$PATH \
IPRO_SDK_BASE=$(pwd) \
make -C apps/bluetooth/le_audio/ipro_le_audio_headset -j8

Build Output

  • Binary: apps/bluetooth/le_audio/ipro_le_audio_headset/build/build_out/ipro_le_audio_headset_IPRO7.bin
  • Latest recorded basic build: 521080 B, SHA256 55074c89ae853bb462af90f3cdd0129a4ccad42cd8163d9774ac2ad20be6473f.

Flash to Device

# $CUBE_UTILS is the utils/ directory of your IntelProCube installation.
# The port name changes with the USB adapter - check `ls /dev/cu.*` rather
# than assuming, and use cu.* not tty.* (the latter blocks on carrier detect).
python3 "$CUBE_UTILS/ipro_probe_ctl.py" \
  dl --port /dev/cu.usbmodemXXXX

"$CUBE_UTILS/ipro_flash.sh" \
  --chipname ipro7 \
  --port /dev/cu.usbmodemXXXX \
  --firmware apps/bluetooth/le_audio/ipro_le_audio_headset/build/build_out/ipro_le_audio_headset_IPRO7.bin

IPRO7AI Reef board

make -C apps/bluetooth/le_audio/ipro_le_audio_headset DEFCONFIG=defconfig_reef
# -> build_reef/build_out/ipro_le_audio_headset_IPRO7.bin
ipro_iot_tool_macos --chipname ipro7 --chip-variant IPRO7AI --port /dev/cu.usbmodemXXXX \
    --firmware apps/bluetooth/le_audio/ipro_le_audio_headset/build_reef/build_out/ipro_le_audio_headset_IPRO7.bin

defconfig_reef is the DAC variant with CONFIG_IPRO7AI_REEF instead of CONFIG_EVB, and CCI analysis off (it claims GPIO0/1/2/11: camera D0-D2 and SW5 on this board). Board behaviour comes from ipro7ai_reef_board_config.h:

  • Output: DAC A feeds both the J2 headphone buffer and the PAM8302A speaker amp (enable GPIO25). While a plug is in J2 (GPIO26 low) the amp is off; it follows the jack during playback. The speaker path is trimmed by -12 dB (dac spk <dB>), because the PAM8302A's 15-30 V/V gain is far above the EVK amp the volume curve was set on. The EVK speaker EQ is off.
  • Keys: SW3 volume down, SW4 volume up, SW5 mute, all through the VCP volume renderer, so the phone's slider follows.
  • 512 kHz output path (dac os 1, the Reef default): the GPDAC runs at 512 kHz and src/dac_ns.c expands each 32 kHz sample with interpolation and first-order noise shaping, which takes the 10-bit quantisation hiss out of the audio band. dac os 0 is the original 32 kHz path, dac os 2 second-order shaping. The expander costs about 8% CPU (ps). It runs at priority 5, below the BLE host threads: at priority 30 the stream lost 4-13% of its ISO packets; at 5, none in 13 000 packets on either path (bench, 2026-10-06). ps and long dacprof/dac status dumps stall it for a moment and can cause a short glitch.

Host test for the shaper: sh test_host/run.sh.

Basic Android phone smoke

With the headset app running on A:

cd <SDK root>
PATH=/opt/toolchain/riscv_ipro7/bin:$PATH \
IPRO_SDK_BASE=$(pwd) \
python3 apps/bluetooth/le_audio/ipro_le_audio_headset/tools/verify_le_audio.py \
  --port /dev/cu.usbmodemXXXX \
  --baud 115200 \
  --duration 45 \
  --device IPRO-LE-Audio \
  --expect-ascs \
  --log /tmp/ipro_android_leaudio_smoke_board.log \
  --json /tmp/ipro_android_leaudio_smoke.json

Latest recorded r48 result:

  • Android found IPRO-LE-Audio, connected, and discovered 1801,1853,1850,184e,1844.
  • The phone bonded successfully; the DUT reported security level 4.
  • This verifies phone visibility/profile connection, not media streaming.

Configuration

Kconfig Options

Key configuration options in .config (DAC.config and UAC.config switch the audio output between the on-chip DAC and a USB Audio Class device):

# LE Audio roles (Zephyr host)
CONFIG_BT_AUDIO=y
CONFIG_BT_AUDIO_RX=y
CONFIG_BT_BAP_UNICAST_SERVER=y
CONFIG_BT_PACS=y
CONFIG_BT_ASCS=y
CONFIG_BT_CAP_ACCEPTOR=y
CONFIG_BT_CSIP_SET_MEMBER=y
CONFIG_BT_VCP_VOL_REND=y

# LC3 decoder
CONFIG_COMPONENTS_LC3_ENABLE=y

Audio Parameters

Configurable in src/app_audio.h:

#define APP_AUDIO_SAMPLE_RATE      48000   // Hz
#define APP_AUDIO_FRAME_DURATION   10      // ms
#define APP_AUDIO_BITRATE          96      // kbps
#define APP_AUDIO_CHANNELS         2       // Stereo

Development Roadmap

Phase 1: Core Features ✅ (Completed)

  • [x] Basic BAP unicast audio streaming
  • [x] LC3 codec integration
  • [x] USB audio bridge
  • [x] VCP volume control
  • [x] Auto-reconnection support

Phase 2: Enhanced User Experience (Q1 2026)

  • [ ] Multipoint Connection: Connect to 2 devices simultaneously
  • [ ] Fast Pair Support: Google Fast Pair for quick pairing
  • [ ] AVRCP Fallback: Support classic Bluetooth for older devices
  • [ ] Battery Optimization: Extend battery life by 30%
  • [ ] Custom EQ: User-configurable audio equalization

Phase 3: Advanced Audio Features (Q2 2026)

  • [ ] Broadcast Audio Scan: Scan and join Auracast broadcasts
  • [ ] Audio Sharing: Share audio with another headset
  • [ ] Spatial Audio: 3D audio positioning support
  • [ ] Hearing Aid Features: Customizable audio amplification
  • [ ] Active Noise Cancellation: ANC integration

Phase 4: Ecosystem Integration (Q3 2026)

  • [ ] CCP Full Implementation: Complete call control profile
  • [ ] HAP Integration: Hearing Access Profile for accessibility
  • [ ] TMAP Support: Telephony and Media Audio Profile
  • [ ] Multi-language Voice Prompts: Localized user feedback
  • [ ] OTA Firmware Update: Over-the-air update via BLE

Phase 5: AI and Smart Features (Q4 2026)

  • [ ] AI Noise Reduction: Deep learning-based noise cancellation
  • [ ] Voice Enhancement: AI-powered voice clarity
  • [ ] Context Awareness: Automatic audio mode switching
  • [ ] Personalized Audio: Learning user preferences
  • [ ] Health Monitoring: Heart rate/activity tracking integration

Technical Specifications

Performance Metrics

  • Audio Latency: 20-40ms (typical)
  • Connection Range: Up to 10 meters (Class 2)
  • Battery Life: 8+ hours continuous playback
  • Standby Time: 200+ hours
  • Charging Time: ~2 hours

Memory Usage

  • Flash: ~550 KB
  • RAM: ~140 KB (OCRAM)
  • PSRAM: ~2 MB (audio buffers)

Supported Platforms

  • IPRO7 Development Board
  • IPRO7 Commercial Modules
  • Future: IPRO8 platform

Troubleshooting

Common Issues

Issue: Headset not discoverable

  • Solution: Check if advertising is enabled: gap advertise on

Issue: No audio output

  • Solution: Verify USB connection and check audio status command

Issue: Poor audio quality

  • Solution: Check RSSI (gap status) and ensure strong BLE signal

Issue: Volume control not working

  • Solution: Ensure VCP is enabled in configuration and source device supports it

Issue: Disconnection during audio playback

  • Solution: Check for interference, reduce distance, or update firmware

References

License

Copyright (c) 2024-2026 INTELPRO Inc. All rights reserved.

Contact

For technical support or questions:

  • Email: support@intelpro.com.tw
  • Website: https://www.intelpro.com.tw