AMA Kit Implementation Requirements

This page lists the requirements that Bluetooth-enabled Alexa Built-in devices must meet to implement the Alexa Mobile Accessory (AMA) Kit. For comprehensive requirements for devices implementing the Alexa Voice Service (AVS), see AVS Security Requirements.

Bluetooth and Bluetooth Low Energy (BLE) Requirements for AMA

A device Bluetooth implementation must meet the following requirements to support AMA:

  • Bluetooth v4.2 dual mode + LE compliance (with DLE support)
  • Standard pairing, authentication, link key, and encryption operation
  • BT Protocols support for SPP/A2DP/HFP /SDP/RFCOMM/SCO
  • Accessories that implement mSBC must be MFi Certified

Codec requirements for AMA

AMA supports following codecs:

  • Opus
  • mSBC

The following table shows the recommended parameter settings for the supported codecs. An AMA enabled device must support at least one codec with the corresponding parameter settings.

CODEC Version Parameter Settings Comments
mSBC   Encoding - MSBC_WITH_PREAMBLE
Sample Frequency - 16000
Sample size in bits - 16
Frame rate = (1000/7.5) // 7.5ms per frame
Frame size = 60 bytes
[x >= 0 && x%8=0] preamble size
Big endian – false
mSBC header size = 64 (used in SBC codec initialization)
Opus CBR 1.2.1 BT
Sample Frequency - 16000
Sample size in bits - 16
Channels – Mono
Encoding format: hard constant encoding
Bit-rate: 64 kbps
Complexity: 4
Frame size: 20 ms

BLE
Sample Frequency - 16000
Sample size in bits - 16
Channels – Mono
Encoding format: hard constant encoding
Bit-rate: 32 kbps
Complexity: 4
Frame size: 20 ms
 

AMA hardware requirements

This section provides the AMA hardware requirements for a Push To Talk (PTT) or wake word enabled device with a custom implementation and OPUS codec support (v1.1.4). Specifications vary by device depending on the chipset, codec support, and implementation. Device-specific custom algorithms also impact specifications.

Wake word, AFE, and other front end algorithms impact additional hardware requirements on the DSP depending on the size and implementation.

  Push to Talk Wake Word
BT version 4.2 or higher 4.2 or higher
BT/BLE audio data minimum throughput 64kpbs 64kpbs
SoC/DSP No specific requirements. Extra MIPS needed depending on choice of audio CODEC, whether to support Alexa COMMS. Extra MIPS needed for Wake Word Engine
RAM No specific requirements Extra memory needed for Wake Word Engine, Pre-roll and Wake Word buffering
NVM Need space for OTA update Need space for OTA update
BT to SoC data Interface Valid values: I2S, UART, SPI or other Recommend to use minimum 1Mbps or faster interface for pre-roll and wake word buffer catch up. Don't use I2S interface because it might cause too long UPL
BT and SoC security Please see AMA Security Requirements section Please see AMA Security Requirements section

AMA software requirements

Your Bluetooth-enabled accessory must support AMA transport and control protocols, including the following requirements:

  • The accessory must encode the user’s utterances with the encoding technologies described in the Codec Requirements for AMA and send the encoded utterances to the Alexa app on a phone by using the AMA Kit Protocol Specification.
  • The accessory must implement functionality to receive Alexa responses from a mobile phone by using the AMA Kit Protocol Specification.
  • The accessory must implement Over-the-Air (OTA) updates through the device companion app, and not through the Alexa app.
  • The accessory must provide device information, such as serial number, name, supported transport, and device type to the AMA protocol stack.

AMA security requirements

The Alexa Developer Services Agreement requires that developers implement all reasonable security measures when developing Alexa Built-in devices. Your device must meet the following minimum requirements for AMA integration.

Refer to the AVS Security Requirements Intake form with your whitelisted Amazon developer account for complete list of security requirements.

Security Feature Requirement Typical response
Secure Simple Pairing - Must support non-zero STK-based Just Works, if display not available (Caution: Does not provide protection against passive eavesdropping and MITM)
OR
Secure Simple Pairing - Must support Numeric Comparison if display available (Caution: Does not provide protection against passive eavesdropping and MITM)
Mandatory Supports Just Works
OR
Supports Numeric Comparison
Bluetooth 4.2 devices and services should support Security Mode 4 Level 4 whenever possible. If security mode 4 level 4 is not available, the device must use Security Mode 4 level 3. Mandatory Yes, supports security mode 4 level 4
BLE devices and services that use Low Energy should implement Secure Connections model using Security Mode 1 Level 4. If security mode 1 level 4 is not available, device must use Security mode 1 level 3. Mandatory Yes, supports security mode 1 level 4
BLE devices must use privacy features, such as Random Resolvable address (RRA) if the device transmits Personally Identifiable Information (PII), such as Heart Rate, GPS, etc. Optional Yes

Infrastructure requirements

Device manufacturers must have the following infrastructure in place:

  • Software maintenance updates – Define a software maintenance update strategy that specifies how to create and distribute software updates within a reasonable period of discovery when vulnerabilities are identified.
  • Contact information – Publish contact information to publicly available websites on how to your company about potential security vulnerabilities in your devices.
  • Security response plan – Implement and share with Amazon a security response plan that describes how your company plans to proceed if a security incident arises, when your company expects to communicate with Amazon on an incident, and the estimated timelines for remediation of an incident.
  • Vulnerabilities report – Submit reports of known exploitable security vulnerabilities that exist on the device along with a plan to fix the vulnerabilities.
  • Independent in-depth security review – Provide a report from a third party security lab authorized by Amazon who has conducted an in-depth security review of the device.

Review the the AVS Security Requirements Intake form with your whitelisted Amazon developer account and to make sure that your device meets the SoC/chipset security requirements outlined in the intake form."