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CMX655D Codec made easily accessible to Raspberry Pi enthusiasts

The global popularity of the SBC (Single Board Computer) has opened up a world of embedded developments that are not easily achievable by any other means. These powerful tools have allowed engineers, software developers and hobbyists to rapidly design solutions to a multitude of problems.

Arguably, the release of the Raspberry Pi kick-started this move towards low-cost projects and product development. Access to a rich ecosystem of open-source software, online forums and hardware ready interfaces has helped grow this sector into every technological corner.  The Raspberry Pi is the most recognised of these SBCs.

The CML CMX655D Ultra-low Power Voice Codec is ideal for use in low power projects and developments typical of those where the Raspberry PI may be found.  The CML CMX655D integrates two matched channels supporting a large variety of digital MEMS (Micro-Electromechanical System) microphones and signal processing capability along with a 1 Watt high-efficiency Class D speaker amplifier.

The EV6550DHAT brings together the CMX655D and the Raspberry Pi by taking the essence of the EV6550D Evaluation board and applying it to the Raspberry Pi HAT hardware.

The Raspberry Pi HAT (Hardware Attached on Top) is a hardware standard defining an add-on board that mounts directly onto the Raspberry Pi and attaches to the 40 way GPIO header. The EV6550DHAT conforms to this standard and integrates the functionality of the CMX655D into the Raspberry Pi environment.

This defined hardware platform along with open-source software simplifies software and hardware development.


The EV6550DHAT:

  • Demonstrates CMX655D functionality.
  • Includes two digital top-ported MEMS microphones.
  • Provides an easy screw connection for 4-8Ohm external speaker.
  • The flexibility to use local or off-board power for the PA.
  • Accessibility to GPIO and test pads enables further options, including alternative MEMS microphones or alternative power supply.
  • Includes an option to add line out phono connector.
  • Provides a simple GUI interface with open-sourced drivers.
  • Conforms to the HAT definition.
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