Connected audio unit
The audio unit handles background music, scheduled announcements and priority messages across professional venues. Content and scheduling are updated remotely from a central server, with no need to visit the site.
Designed and developed in France by EMBELEC.
Key points
High-quality audio playback
MP3 played at up to 320 kbit/s. Audio converter rated at 110 dB dynamic range.
Crossfade between tracks
Two tracks overlap: the sound atmosphere never breaks.
Playback continues without a network
Files live on an SD card. An Ethernet or cellular outage does not interrupt playback.
Managed and updated remotely
Playlists, configuration, messages and firmware updates all come from the server. No site visit required.
Strict network client
No listening service, no port exposed on the network.
Designed for CRA compliance
The European cyber-resilience regulation’s requirements are built in from the design stage.
Applications
Retail and store networks
Consistent musical atmosphere across the whole network, scheduled promotional announcements, central control from head office.
Hotels and restaurants
Continuous background music thanks to crossfading, with scheduling that varies by time of day.
Industrial sites and construction
Announcements and instructions on sites with no wired network, thanks to cellular connectivity.
Specifications
Processing
- Microcontroller
- Arm® Cortex®-M33 File decoding, crossfade, encrypted link to the server, SD-card playback
Audio
- File format
- MP3 (MPEG-1 Layer III) Bit rate up to 320 kbit/s (CBR) Sampling rate 44.1 kHz and 48 kHz
- Audio codec
- 110 dB dynamic range in differential stereo Output level 2 V RMS differential, 1 V RMS single-ended
- Crossfade
- Two simultaneous tracks, constant-power law, adjustable duration
- Audio output
- 3.5 mm stereo jack RCA connectors
- Built-in processing available
- Digital volume control, programmable per-channel gain, equaliser and biquad filters, programmable high-pass filter, low-jitter PLL
Network connectivity
- Ethernet
- 10/100 Mbit/s, RJ45 with integrated magnetics Galvanic isolation
- Architecture
- Strict TCP/IP client — no listening network service IP address: DHCP or static address Encryption: TLS with server certificate verification
- Cellular
- Optional 4G / 5G
Power supply
- Connector
- USB-C — power only, no data transfer function 5 V, no USB-PD
Storage and content
- Local storage
- SD card — MP3 files played locally File system: FAT32
- Offline playback
- Self-sufficient from locally stored content, independent of the network
- Scheduling
- Playlist defined and pushed to the board by the server
- Priority messages
- Played at fixed times, defined and pushed by the server
- Real-time clock
- Coin-cell backed — date and time retained when unpowered
Updates and monitoring
- Firmware
- Updated remotely by the server Cryptographically signed firmware and anti-rollback protection
- Content
- Updated remotely from the central server
- Monitoring
- Status reporting and remote diagnostics
- Local indicators
- Status LED
Security and compliance
- Cyber Resilience Act (EU 2024/2847)
- Designed for compliance — default category
- RED Directive (EU 2014/53)
- Applicable on account of cellular connectivity
- Default credentials
- No account and no password: the unit exposes no administration interface
- USB-C port
- Power only — no usable data interface
- Certificate validity
- Checked using the battery-backed real-time clock
- Software bill of materials (SBOM)
- Provided, in CycloneDX or SPDX format
- Logging
- Security events
- Debug interfaces
- Disabled in production configuration
Environment
- Operating temperature
- −20 °C to 85 °C
What sets this unit apart
Connectivity that suits every site
Many audio distribution products on the market rely solely on a wired or Wi-Fi link. The optional cellular connectivity covers sites where no wired network is available, with no additional installation work.
Playback does not stop when the network does
Files are stored locally on an SD card. If the Ethernet or cellular link drops, playback continues uninterrupted from the content already present. The network is there to refresh content and scheduling, not to feed playback.
A network architecture that reassures IT departments
The product operates purely as a client: it initiates connections to your server and exposes no service on the network. That is often the deciding factor when connecting third-party equipment to a corporate network.
An audio chain specified beyond the format
The chosen converter is rated at 110 dB dynamic range and 2 V RMS differential output — well beyond what an MP3 stream demands, even at its highest bit rate. Performance of the assembled product will be measured on prototype.
Regulatory compliance anticipated
From 11 December 2027, products with digital elements placed on the European Union market will have to comply with the Cyber Resilience Act. Its requirements are built in from the design stage: secure boot, signed firmware, software bill of materials, vulnerability management.
Full control of the design
Electronics, firmware and software are developed in-house: functional changes, custom adaptations and ongoing security maintenance do not depend on a third-party supplier.
Documentation supplied
- EU declaration of conformity
- Software bill of materials (SBOM) in CycloneDX or SPDX format
- Vulnerability disclosure policy and security contact point
- Installation and secure configuration guide
- Support and security patching commitment
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