Overview:
ReSpeaker 4-Mic Array for Raspberry Pi is a quad-microphone expansion board for Raspberry Pi designed for AI and voice applications. This means that we can build a more powerful and flexible voice product that integrates Amazon Alexa Voice Service, Google Assistant, and so on.
Developed based on AC108, a highly integrated quad-channel ADC with I2S/TDM output transition for high definition voice capture, which allows the device to pick up sounds in a 3 meters radius. Besides, this 4-Mics version provides a super cool LED ring, which contains 12 APA102 programable LEDs. With that 4 microphones and the LED ring, Raspberry Pi would have ability to do VAD(Voice Activity Detection), estimate DOA(Direction of Arrival), do KWS(Keyword Search) and show the direction via LED ring, just like Amazon Echo or Google Home.

Features:
Raspberry Pi compatible(Support Raspberry Pi Zero and Zero W, Raspberry Pi B+, Raspberry Pi 2 B and Raspberry Pi 3 B)
4 Microphones
3 meters radius voice capture
2 Grove Interfaces
12 APA102 User LEDs
Software Algorithm: VAD(Voice Activity Detection), DOA(Direction of Arrival) and KWS(Keyword Search)
Note:
There is no audio output interface on ReSpeaker 4-Mic Array for Raspberry Pi. It is only for voice capture. We can use the headphone jack on Raspberry Pi for audio output.

Application Ideas:
Voice Interaction Application
AI Assistant

Hardware Overview:

MIC: 4 analog microphones
LED: 12 APA102 programable RGB LEDs, connected to SPI interface
Raspberry Pi 40-Pin Headers: support Raspberry Pi Zero, Raspberry Pi 1 B+, Raspberry Pi 2 B and Raspberry Pi 3 B
AC108: highly integrated quad-channel ADC with I2S/TDM output transition
I2C: Grove I2C port, connected to I2C-1
GPIO12: Grove digital port, connected to GPIO12 & GPIO13
Note:
If we want to use the APA102 RGB LEDs, please write HIGH to GPIO5 first to enable VCC of the LEDs.

[User Guid & Resource]
please refer to the [Download Link]