Using emUSB-Device Audio, an embedded device can be transformed into an audio recorder or an audio speaker. An audio jack and dedicated audio hardware is not necessarily available on every design. emUSB-Device Audio allows the device to handle audio data irrespective of the available hardware, for example audio data played from a PC (Linux/Windows/Mac) can be saved directly onto an SD card.
The audio class is the foundation for any embedded device handling audio data. Whether it has a microphone or speaker, or whether it simply functions as an audio editor.
Typical applications range from speaker phones, conferencing systems, or headsets, to music instruments, voice recorders, music players, or sports wearables.
USB sound card
SEGGER’s implementation of the Audio class V1.0 is designed with minimal resource usage in mind, especially targeted to embedded devices. The implementation supports the usage of a “speaker” (input/output audio terminal with a feature terminal for controls) and a “microphone” (input/output audio terminal).
The speaker and microphone can be used independently of each other; both can be enabled at the same time allowing audio transfer in either direction.
The Audio class supports adaptive synchronization for OUT endpoints, asynchronous synchronization for IN endpoints and synchronous synchronization type for both directions; commands SET_CUR, GET_CUR, SET_MIN, GET_MIN, SET_MAX, GET_MAX, SET_RES, GET_RES for the speaker interface feature unit controls are supported (volume, mute, etc.).
emUSB-Device-Audio does not provide drivers/codecs for any audio peripherals. Writing a driver to interface with the audio hardware is the responsibility of the customer.
With emUSB-Device-Audio Audio data is transferred in the PCM encoding. The Audio class transfers multiple audio samples in a single packet. In the demo below the speaker interface of the audio class is configured with 2 channels (stereo) and 16 bit data per channel.
Download the emUSB-Device Audio demo for the emPower board:
- Program the emPower with the default application using Embedded Studio
- Connect the HS USB connector to your PC
- Select the emUSB-Device Audio demo as your default sound output and sound input device
- Play audio which will be saved onto the SD card
- Loopback the emUSB-Device Audio microphone to your speakers to listen to the audio demo
Enhance your embedded device with audio capabilities!