The XMOS VocalFusion Stereo Dev Kit for Amazon AVS (Digi-Key part number 880-1130-ND) is a Raspberry Pi specific dev kit to help with the development of “far-field voice capture and processing” applications for the Amazon Alexa Voice Service (AVS). “Far-field voice capture” technology “aims to enable smart devices to recognize distant human speech (usually 1m to 10m).” Through the Amazon AVS technology, it is not necessary to “train” a voice recognition system. The system is ready to go out of the box. Figure 1: XMOS VocalFusion Stereo Dev Kit for Amazon AVS. (Image source: XMOS)
What’s included:
Linear array of 4 omni-directional microphones: up to 180° capture, for ‘edge of the room’ applications
Low-jitter audio clock
Configurable user input buttons and LEDs
I2S audio and I2C control connectivity
USB power, with optional USB 2.0 device audio and control connectivity
40-pin Raspberry Pi interface cable (see Figure 3 for the pinout)
What’s not included but needed:
Raspberry Pi – Digi-Key part number 1690-1025-ND
Power adapter (minimum 2 A recommended) – Digi-Key part number 1690-1022-ND
SD card (minimum 16 GB recommended) – Digi-Key part number 1582-1004-ND
Speaker
USB keyboard
USB mouse – Digi-Key part number CH969-ND
Monitor with HDMI input or Raspberry Pi touchscreen – Digi-Key part number 1690-1007-ND
HDMI cable – Digi-Key part number Q396-ND (not needed if you are using 1690-1007-ND)
Ethernet connection with internet connectivity
VocalFusion Stereo Dev Kit block diagram is shown in Figure 2. It includes:
VocalFusion XVF3500 Voice Processor
Four MEMS microphones on a separate board
A micro-USB connector for power (and optionally USB 2.0 device connectivity)
Extension headers for I2S and I2C control connectivity
Four general purpose push-button switches
13 user-controlled LEDs
Low-jitter clock source
An xSYS connector for an xTAG debug adapter
Figure 2: VocalFusion Stereo Dev Kit Block Diagram. (Image source: XMOS)
XMOS provides a straight-forward setup guide. One note to keep in mind, the 40-pin Pi connector is not keyed so it is worth a second check to make sure the connector is placed correctly (see Figure 3). Figure 3: RPi 40-pin connector. (Image source: XMOS)
Please see Figure 4 for additional information on the Raspberry Pi pinout. Figure 4: Raspberry Pi Cable Pinout. (Image source: XMOS)
Install Raspbian
Download Raspbian Stretch by following this link.
Put the SD card into the computer via the SD card slot or a USB adapter.
Install the downloaded image onto the SD card by following these instructions (based on the OS you are using):
Linux Terminal
Ctrl-Alt-T will open a new terminal window.
At the command prompt type l***lk to get the address of the SD card, it could be either /dev/mmcblk0 or /dev/sdb or something similar.
Run Etcher and select the 2018-06-27-raspbian-stretch.zip.
Select the SD card drive.
Click “Flash”.
Wait until the image is written and eject disk.
Install and Setup Amazon AVS
Follow this link to the Raspberry Pi Quick Start Guide, which will walk you through the process of installing the necessary dependencies and getting the Amazon AVS up and running. When this is finished, type: sudo reboot.
Run Amazon AVS
Figure 1: XMOS VocalFusion Stereo Dev Kit for Amazon AVS. (Image source: XMOS)
Figure 2: VocalFusion Stereo Dev Kit Block Diagram. (Image source: XMOS)
Figure 3: RPi 40-pin connector. (Image source: XMOS)
Figure 4: Raspberry Pi Cable Pinout. (Image source: XMOS)
