CMX655D was designed for digital voice and sensor applications. The device includes the whole signal chain, from dual matched digital MEMS microphone interfaces to a 1W Class D speaker driver, with decimation, filtering, signal processing and digital gain. For connectivity, the device provides an I2S/PCM audio interface and SPI control interface. It is a single-chip, ultra-low-power solution for advanced voice coding/decoding.
The EV6550DHAT uses its 40-pin extended GPIO connector to connect to any Raspberry Pi and is powered by the Raspberry Pi. It also has a connection for an external power source in case other HATs are using the Raspberry Pi’s power supply.
The EV6550DHAT’s open-source software is accessible through apps and projects including GTK3+. GEANIE and GLADE, making the GUI used to access the EV6550DHAT easily modifiable and accessible.
Features include access to pre-recorded sample files, as well as the ability to record and playback audio files in the .wav format, allowing the play back of pre-recorded samples at different rates and levels. This allows the easier comparison of settings and how they influence audio quality. Configurable parameters include sample rate (8, 16, 32 or 48ksample/s), volume and level (dB). Audio input gain can be set between -12dB to +3dB, while playback volume can be set between -90dB to 0dB. Muting and ‘smoothing’ is also supported.