Synaptics AudioSmart User manual

Synaptics AudioSmart® 2-Mic Development Kit for
Amazon AVS
PN:
511-000841-01 Rev C

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 2
Contents
1. Introduction ...................................................................................................................................................... 5
1.1. Target Audience .................................................................................................................................... 5
1.2. References ............................................................................................................................................ 5
1.3. Definitions, Acronyms, and Abbreviations........................................................................................... 5
2. Overview ........................................................................................................................................................... 6
2.1. CX20921 Evaluation Board.................................................................................................................. 7
2.2. Pin Definition......................................................................................................................................... 8
3. Using the Development Kit.............................................................................................................................. 9
3.1. Hardware Setup .................................................................................................................................... 9
3.1.1. Connecting the Evaluation Board to the RPi3 ...................................................................... 9
3.2. Software Setup ................................................................................................................................... 12
3.2.1. Writing Raspbian OS to the MicroSD Card.......................................................................... 12
3.3. Install, Configure, and Build the SDK ................................................................................................ 13
3.4. Running the Setup .............................................................................................................................. 17
3.5. Verifying the Setup.............................................................................................................................. 19
4. Installing the Cypress Siena USB-to-I2C Device Driver ................................................................................. 20
4.1. Flashing New Firmware ...................................................................................................................... 22
5. Troubleshooting.............................................................................................................................................. 24
6. Revision History.............................................................................................................................................. 25

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 3
List of Figures
Figure 1. Development Kit Components .................................................................................................................... 6
Figure 2. CX20921 Evaluation Board: Connections, Interfaces and Devices.......................................................... 7
Figure 3. RPi3 pinout................................................................................................................................................... 8
Figure 4. CX20921 evaluation board setup with RPi3 board and Mic board (with 2-mic attached)...................... 9
Figure 5. Connections for CX20921 evaluation board and Mic board (with 2-mic attached) .............................. 10
Figure 6. Connections for RPi3 .................................................................................................................................11
Figure 7. Example fcp folder .....................................................................................................................................22
Figure 8. Build folder contents .................................................................................................................................22

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 4
List of Tables
Table 1. References .................................................................................................................................................... 5
Table 2. Definitions...................................................................................................................................................... 5
Table 3. CX20921 to RPi3 connections ...................................................................................................................11

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 5
1. Introduction
This document provides step-by-step introductions on setting up the Synaptics AudioSmart®2-Mic
Development Kit for Amazon™ AVS. This document describes how to make the necessary hardware
connections, install the driver, flash the firmware (only when needed), set up the Amazon Alexa™ Voice Service
(AVS), and switch between the keyword detection (voice trigger) modes.
1.1. Target Audience
This document is intended for manufacturers and developers for creating Smart Home device prototypes that
use the Synaptics AudioSmart 2-Mic Development Kit and the Raspberry Pi 3 (RPi3) (not provided with the kit)
to offer an ideal Voice Control experience via Amazon’s Alexa Voice Service.
1.2. References
Table 1. References
Name Description Location
I2C I2C Specification http://www.nxp.com/documents/user_manual/UM10204.pdf
ACPI Advance Configuration and Power Interface http://www.acpi.info/DOWNLOADS/ACPIspec50.pdf
RPi3 An open source code single-board
computer
https://www.raspberrypi.org/products/raspberry-pi-3-model-b/
ALSA The Advanced Linux Sound Architecture
(ALSA) provides audio and MIDI
functionality to the Linux operating system.
http://www.alsa-project.org/main/index.php/Main_Page
ASoC ALSA system on Chip for I2S codecs http://www.alsa-project.org/main/index.php/ASoC
Sensory Wake word engine plug-in for Raspberry Pi https://github.com/Sensory/Alexa-rpi
1.3. Definitions, Acronyms, and Abbreviations
Table 2. Definitions
Term Definition
AVS Alexa Voice Service
DSDT Differentiated System Description Table
GPIO General-Purpose Input/Output
I2C Inter-Integrated Circuit
RPi3 Raspberry Pi 3

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 6
2. Overview
The Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS contains the following:
•CX20921 evaluation board, pre-flashed with firmware for the CX20921 device.
•Microphone module with two omnidirectional mics
•Stereo 3.5 mm male-to-male audio cable
•Micro-USB cable
•Type A to Type B USB cable
•Cable assembly (colored wires)
•+5V power supply for CX20921 evaluation board
Note:
•Micro SD card of at least 8 GB is required
•Powered speakers, RPi3 board, and micro SD card are all mandatory for the set up but are NOT included
in the Synaptics AudioSmart 2-mic Development Kit.
•Proper speaker protection will enhance overall performance. See External Loudspeaker Guidelines
and Recommendations for Smart Speaker Applications (PN: 507-000837-01) document for additional
information.
Figure 1 . Development Kit Components

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 7
2.1. CX20921 Evaluation Board
Figure 2 . CX20921 Evaluation Board: Connections, Interfaces and Devices

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 8
2.2. Pin Definition
Figure 3 shows the RPi3 pinout definition. Pins 13 and 14 are used and are emphasized in red.
Figure 3 . RPi3 pinout

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 9
3. Using the Development Kit
3.1. Hardware Setup
Connect the CX20921 evaluation board and the RPi3 (not provided with the kits).
3.1.1. Connecting the Evaluation Board to the RPi3
Make the following hardware connections between the CX20921 evaluation board and the RPi3 (not provided
with the kit), as shown in Figure 4 and Figure 5.
Figure 4 . CX20921 evaluation board setup with RPi3 board and Mic board (with 2-mic attached)

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 10
Figure 5 . Connections for CX20921 evaluation board and Mic board (with 2-mic attached)
1. Connect the 3.5 mm audio jack on the RPi3 (J7) to LINEIN on the CX20921 evaluation board (J25).
2. Connect audio jack (J3) (Line Out labeled as HP) on the CX20921 evaluation board to a powered
speaker.
3. Connect the microphone module to the CX20921 evaluation board (J19).
a. Spacing between the left MIC and right MIC should be set to 55 mm with the preloaded
configuration (see Figure 4).
b. Software tool (FCP Essential) will be provided for mic distance adjustment between 30 mm –
120 mm.
4. Connect the audio path from micro USB (J1) to USB port on RPi3.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 11
5. Using the Cable Assembly, connect GPIO1 at pin 2.14 from the CX20921 evaluation board to J8.pin13
on the RPi3, and the other wire from the Cable Assembly to Ground (GND) at pin 2.15 from the
CX20921 evaluation board to J8.pin 14 on the RPi3.
Figure 6 . Connections for RPi3
Table 3. CX20921 to RPi3 connections
Signal RPi3 CX20921 evaluation board
GPIO (indicating trigger detected in CX20921 J8. Pin 13 (GPIO_GEN2) GPIO1, P2. Pin 14
Ground J8. Pin 14 (Ground) GND, P2. Pin 15
Audio Signal from RPi3 3.5 mm audio jack (J7) LINEIN (J25)
Processed microphone signal from CX20921
evaluation board USB port Micro USB (J1)
6. Connect the power supplies for both the CX20921 evaluation board, (J10, +5V power supply included)
and the RPi3 (J1).
a. Switch the power switch (SW3) to turn on the CX20921 evaluation board.
b. LED D6 (5VLED) will turn on when there is power on the board.
•Proper speaker protection will enhance overall performance. See External Loudspeaker Guidelines
and Recommendations for Smart Speaker Applications (PN: 507-000837-01) document for additional
information.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
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3.2. Software Setup
3.2.1. Writing Raspbian OS to the MicroSD Card
1. Format the SD card. This can be done by going to the 'Computer' folder and right clicking on the SD
card. Click Format… to display the format options. When reformatting, confirm that the File system is
FAT32 or FAT, as shown below.
2. Download the Raspbian Stretch OS. The zip file is located at the following link:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2018-11-15/
3. Unzip and write the downloaded image to the SD card using Win32DiskImager. This tool can be found
at the following link: https://sourceforge.net/projects/win32diskimager/
4. Run the Win32DiskImager to write the image to the SD card.
oBrowse to the subdirectory icon and select the image file.
oSelect the device drive in the Device drop down menu to write the Raspbian OS.
oClick Write to write the image to the SD card.
5. After the image has finished writing, insert the microSD card into the RPi3.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 13
3.3. Install, Configure, and Build the SDK
1. Insert the microSD card with the Raspbian Stretch OS installed in the RPi3.
2. Power on the RPi3 using the included +5V supply.
3. When the desktop loads, establish a WLAN or LAN connection.
4. Open a terminal and send the following command to get the files necessary for installing the SDK.
$ git clone https://github.com/conexant/avs-device-sdk.git
The following shows a screen with representative results:
5. After the files are downloaded, go into the avs-device-sdk directory and run the install.sh script.
$ cd avs-device-sdk
$ bash install.sh
6. Several screen prompts will follow. You will need to provide your account credentials and answer
several prompts. Depending on your answers to the prompts, you may need to acknowledge the
Sensory license agreement.
Note: If you haven’t already registered your device, you can do so at
https://developer.amazon.com/alexa/console/avs/home . To create a security profile, go to
https://github.com/alexa/avs-device-sdk/wiki/Create-Security-Profile for step-by-step instructions.
a. ClientId: Type in the ClientId and press Enter.
b. ProductId: Type in the ProductId and press Enter.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 14
7. After the ClientId and ProductId are entered, you will be asked if your kit has an LED ring. Select 1 for
no LED ring.
8. Next you will be asked to select which playback path to use. Select 1for RPi.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 15
9. Next you will be asked to select which recording path to use. Select 1 for USB from DSP.
10. Next you will be asked to select the keyword detector to run on the RPi. If you are planning to use the
Embedded Synaptics Smart Trigger (recommended) select 3 for None. Otherwise select 1 for Sensory.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 16
11. If Option 1 was selected in Step 10, then select 2for None. If Option 3 was selected in Step 10, then
select 1 for GPIO.
12. Next you will be asked if you want keyword cloud revalidation on or off. Select 1 for On.
This starts the installation, which will take less than an hour to finish.
13. Once the hardware and software setup is complete, refer to Running the Setup to run the 2-mic setup.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
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3.4. Running the Setup
1. Configure volume settings before running the sample app. Open a terminal and send the following
command:
$ alsamixer
2. Configure the volume setting for the bcm2835 ALSA sound card as well as the I2S RX 16K TX 48K
sound card. The following screens show the RPi3 user interface for these settings.
3. After configuring both cards, exit the alsamixer and send the command:
$ sudo alsactl store
4. Open a terminal and send the following command to run the sample app:
$ bash run.sh

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 18
5. When the sample app is running for the first time, you will be asked to authorize. Find the following
message (you may have to scroll up a bit):
6. Open a browser and go to https://amazon.com/us/code (this can be done on your RPi3 or PC) and log
into the Amazon account you wish to use.
7. Enter the code found in the AVS app (shown in previous picture) and hit continue.
Once you see the message ‘Success! Your registration is now complete’. You should also see “Authorized!” in
the terminal message.
The sample app is now ready to be used, try asking Alexa a question!

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 19
3.5. Verifying the Setup
To verify whether the setup is done properly, please say Alexa followed by a question or command.
•A green LED will light up if Alexa wake word is heard. This confirms that the DS20921 evaluation
board is working properly.
oIf the green LED does not light up when speaking less than 1m away, check the power connection.
•A voice feedback can be heard if the development kit is successfully connected to the AVS network.
oIf there is no voice feedback, check whether the speaker is powered on and all cables are
connected properly between the evaluation board and RPi3.
To learn more about Amazon Alexa Voice Service and access the AVS API reference guide, see the following
link: https://developer.amazon.com/alexa-voice-service/sdk.
Amazon, Alexa, and all related logos are trademarks of Amazon.com, Inc. or its affiliates.

Synaptics AudioSmart 2-Mic Development Kit for Amazon AVS PN: 511-000841-01 Rev C
Copyright © 2019 Synaptics Incorporated. All Rights Reserved. 20
4. Installing the Cypress Siena USB-to-I2C Device Driver
A driver must be installed to enable the onboard Cypress®Siena USB-to-I2C device. Once enabled, this device
allows you to communicate with the CX20921 evaluation board over I2C. This is necessary to flash firmware.
1. Connect the Type A to Type B USB cable between your laptop and the CX20921 evaluation board to
connector J2.
a. This cable interfaces to a Cypress USB-to-I2C control device, allowing you to control
parameters of the CX20921 evaluation board using a Conexant GUI.
b. This cable can also be used to flash new Firmware to the CX20921 evaluation board if
needed (see "Flashing New Firmware" on page 16).
2. The Cypress Siena driver that enables USB-I2C communication between your laptop and the CX20921
evaluation board can be downloaded from:
https://raw.githubusercontent.com/wiki/conexant/avs-device-sdk/assets/Conexant_Siena_Driver.rar
a. Filename: Conexant_Siena_Driver.rar
b. Extract the Conexant_Siena_Driver.rar file onto your laptop.
3. Run the Setup.exe file included in the Conexant_Siena_Driver folder as shown below:
4. When the following message appears. Click Yes.
In the Device Manager, you should see the Conexant Siena USB Driver appear under the Universal Serial Bus
controllers hierarchy.