The Cloud2GND Bumblebee LE Audio Demonstrator, featuring the Panasonic PAN1783 Bluetooth LE module, demonstrates high-fidelity Bluetooth LE Audio applications. The Bumblebee board includes amplifiers, drivers, audio connectors, and other components to provide an out-of-box Bluetooth LE Audio experience. The board is configurable for various use cases, such as point to point connected audio, stereo audio to left/right devices (aka “True Wireless Stereo”), and audio broadcast (AuracastTM ).
Key Features
- PAN1783 Bluetooth Low Energy 5.3 Module
- Diodes Inc. PAM8965 class D amplifier
- AKM AK4558 stereo ADC/DAC
- Infineon IM69D130 MEMS microphone
- Left and right speaker connections
- Line-in and line-out 1⁄8” audio jacks
- Powered over USB or external power supply
- NFC type 4 tag
Applications
- True Wireless Stereo audio (TWS) to left/right receivers
- Multi-channel audio broadcast (1-to-N) (AuracastTM)
- Connected bi-directional audio
LE Audio Specification
Unidirectional CIS/BIS: 16-bit 48 kHz audio sampling, 96 kbps LC3 encoding (per channel)
Bi-directional CIS (LINE IN): 16-bit, 48 kHz audio sampling, 64 kbps LC3 encoding
Bi-directional CIS (MIC): 16-bit, 16 kHz audio sampling, 64 kbps LC3 encoding
Audio Performance (ADC/DAC)
Supported speaker impedance: 4 – 16 ohms, 10W max in to 4 ohms (1% THD+N)
Noise Floor ADC->DAC Shorted Input
< 6 uV RMS unweighted (-104 dBV) (10-22.4 kHz)
< 4 uV RMS A-weighted (-108 dBV)
THD+N 1 kHz ADC->DAC
900mV (-1 dBV) input: 0.004% (-88 dB) typical unweighted
700mV (-3 dBV) input: 0.003% (-90 dB) typical unweighted
THD+N 1 kHz DAC only
0 dBFS 900mV (-1 dBV) out: 0.0025% (-92 dB) typical unweighted
-60 dBFS 900uV (-61 dBV) out: 0.5% (-45 dB) typical unweighted
THD+N (dB) versus signal level for ADC in to DAC out. Clipping occurs above 900 mV RMS input.
ADC in (1 kHz, 880 mV RMS) to DAC out. 64K FFT, AP Equiripple window, 32 averages.
nRF5340 generated 1 kHz 0 dBFS DAC out. 64K FFT, AP Equiripple window, 32 averages.
nRF5340 generated 1 kHz (approx.) -60 dBFS DAC out. 64K FFT, AP Equiripple window, 32 averages.
Audio Performance (Amplifier)
The Bumblebee board includes a 2 channel amplifier that can output up to 10 watts into a 4 ohm load.
Amplifier measurements were made with a 4 ohm + 30uH load and used an AES-17 filter to reduce the switching noise seen by the AudioPrecision measurement instrument. The right channel was used, with +18 dB gain. 20 Hz – 22.4 kHz measurement bandwidth.
Measurements
Noise floor: <160 uV RMS -76 dBV (ADC in shorted → DAC → AMP output)
THD+N: < 0.03% 1 kHz at 500 mV (ADC in → DAC → AMP output)
PAM8965 limiter example with +18 dB gain setting. ADC in → DAC out → AMP out. Beyond 900 mV in the ADC will start hard clipping.
Power Sources
- USB-C (2 amp USB standard may limit speaker output level)
- 2.1 mm center-positive barrel connector
- Greater than 3 amp supply recommended for 2 channel output at max power
Typical current draw with amplifier disabled is less than 40 mA.
Settings
The following tables show the functions of the major switches and jumpers on the Bumblebee board for the initial firmware release. Many of these functions are controlled by firmware and are subject to change when firmware is updated. In addition, not all combinations of settings are valid. See the Bumblebee LE Audio Demonstrator User’s Guide for detailed configuration and operating instructions.
SW1 – Application
| Setting | Description |
| 1 | Unidirectional Connected |
| 2 | Bi-directional Connected |
| 3 | Unidirectional Broadcast |
| 4 | Reserved |
SW3 – Role
| Setting | Description |
| A | Behavior varies by application |
| B | Behavior varies by application |
| C | Reserved |
| D | Reserved |
SW4 – Audio Input
| Setting | Description |
| USB | USB connector |
| Mic | MEMS microphone |
| Line | Line In connector |
| Test | Reserved |
SW6 – Option
| Setting | Description |
| W | 48 kHz sampling |
| X | 16 kHz sampling |
| Y | Reserved |
| Z | Reserved |
SW2 – TWS / ID
| Bit | Description |
| 7 | Received Audio Channel ON=Left, OFF=Right |
| 6:0 | Board ID (for pairing) |
J11 – Pwr Sel
| Bit | Description |
| USB | Powered over USB |
| Ext | Powered over 5V connector |
J15 – AMP Dis
| Option | Description |
| Off | AMP is disabled |
| On | AMP is controlled by firmware |
| Open | AMP is always on |
J20 – Gain
| Option | Description |
| +6 | +6 dB |
| +26 | +26 dB |
| Open | +18 dB |
Revision History
| Revisions | Date | Description |
| 1.0 | 1/10/2024 | Initial release. |
Legal Notice
All contents © 2023 Cloud2GND, LLC and its subsidiaries.
This document and its contents are intended only for use with Cloud2GND products or in relation to Cloud2GND services. Use of this document or its contents in any other manner violates these terms and duplication, reproduction, or any other use of this document is expressly prohibited without prior written permission.
ALL INFORMATION IS PROVIDED AS-IS. CLOUD2GND MAKES NO REPRESENTATIONS OR WARRANTIES ON ANY KIND RELATED TO THE INFORMATION CONTAINED IN THIS DOCUMENT. IN NO EVENT SHALL CLOUD2GND OR ITS SUBSIDIARIES, PARTNERS, OR REPRESENTATIVES BE LIABLE FOR INDIRECT, SPECIAL, PUNITIVE, INCIDENTAL, OR CONSEQUENTIAL LOSS, DAMAGE, COST, OR EXPENSE OF ANY KIND RELATED TO THIS INFORMATION OR ITS USE.
For additional information please contact [email protected]
TradeMarks
The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. The AuracastTM word mark and logos are trademarks owned by Bluetooth SIG, Inc. Any use of such marks by Cloud2GND is under license. Other trademarks and trade names are those of their respective owners.
