AMA Kit Implementation Requirements
The following sections list 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
The Bluetooth implementation for a device 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 the following codecs:
- Opus
- mSBC
The following table shows the recommended parameter settings for the supported codecs.
CODEC | Version | Parameter settings | Comments |
---|---|---|---|
mSBC | – | Encoding - MSBC_WITH_PREAMBLE Sample Frequency - 16000 Sample size in bits - 16 Frame rate = (1000/7.5) // 7.5 ms 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
The following table 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.
Requirement | Push to talk | Wake word |
---|---|---|
BT version | 4.2 or higher. | 4.2 or higher. |
BT/BLE audio data minimum throughput | 64 Kpbs. | 64 Kpbs. |
SoC/DSP | No specific requirements. Extra MIPS needed depending on choice of audio CODEC, whether to support Alexa Communications. | 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 using minimum 1 Mbps 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 | See the AMA Security Requirements section. | See the 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. Then, the accessory sends 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.
Security feature | Requirement | Typical response |
---|---|---|
Secure Simple Pairing - Must support nonzero STK-based Just Works, if display not available (Caution: Doesn't provide protection against passive eavesdropping and MITM). OR Secure Simple Pairing - Must support Numeric Comparison if display available (Caution: Doesn't 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 isn't 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 isn't 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 security lab authorized by Amazon who has conducted an in-depth security review of the device.
Review 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.
Related topics
- About the Alexa Mobile Accessory (AMA) Kit
- Get Started with the AMA Kit
- AMA Kit Functional Requirements