Cableless real-time audio

The goal of this project is to create a device for digital high-quality low latency audio transmission.

The desired parameters are:

  • >= 16-bit resolution
  • <=5ms latency
  • >5h of battery life
  • >= 20m plain field range
  • Configurable input and output type (line, mic, phono…)
  • Channel-based operation to select one of many devices

Rev.:A overview

  • ESP32
  • AK4619VN codec (24/32 bit, 192kHz)
  • DWM1000 (6GHz, 6.8Mbps UWB transceiver)

Rev. A PCB design can be found here.

Known issues

During SW development, it turned out that ESP32 wasn't the best choice for this type of application as it is struggling to receive the WiFI packets at the rate needed.
Initial tests with DWM1000 proved that it might be usable, but continual transmission violates the EU UWB regulations that allow only a duty cycle of 5%/min and 0.5%/hr with bursts <=5ms.

To solve those issues ESP32S3-based Rev. B is being developed.
Redesigned as CRTA Alpha.

CRTA Alpha

Due to many hardware changes, a new design was created.
This design is closer to the final look and form factor.
Another revision is planned, as the configurable audio in/out is not currently implemented.
The UWB transceiver was removed due to regulatory issues, and the ESP32 was replaced with the newer ESP32C6 (alternatively, ESP32S3).
The board is designed for use with either ESP32C6 or ESP32S3. This is achieved by solder jumpers, as both modules are mostly pin-compatible.
A second USB-C connector was added because both ESP32s are equipped with USB peripherals. For the ESP32S3, this enables the possibility of implementing UAC to use the device as a USB audio sink/source.
An OLED display and buttons (or a 5-way switch) have also been added.
The PCB size was reduced mainly to allow it to be mounted on top of a flat 2Ah Li-Pol battery.

The new PCB design for CRTA Alpha is in this branch.

We are awaiting the manufacturing of the PCBs.