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Device Attribute Message Protocol

The Afero architecture uses a messaging protocol that is independent of the wireless technology used. This protocol provides a simple way for the client application to set or get attributes on the ASR module.

You will need the information on this page only if you are implementing the protocol yourself, not using afLib or afLib2 API. If you are using the API to communicate with ASR, the information below will be implemented for you.

The format of the messages is defined below:

Message uint16_t Message length including header
Header uint8_t

Message type:

0x0B = Set

0x0C = Get

0x0D = Update


Request ID:

  0 = Transaction initiated from peripheral

>0 = Transaction initiated from authenticator

Set uint16_t Attribute ID
uint16_t Value length
n bytes Variable-length attribute value
Get uint16_t Attribute ID
Update uint16_t Attribute ID

Update state:

0x00 = Updated

0x01 = Interrupted; device-side update in progress or preempted by device-side update

0x02 = Unknown attribute ID

0x03 = Length exceeded

0x04 = Conflict; previous Set in progress

0x05 = Timeout; Set operation timed out

0xAA = Invalid state; Cloud received unrecognized state value


Update reason:

0x00 = Unknown

0x01 = Unsolicited Afero module-initiated or MCU-initiated Update; e.g., button press

0x02 = Response to Cloud-initiated Set

0x03 = Response to MCU-initiated Set

0x04 = Linking completed

0x05 = A bound attribute was changed

0x06 = Reserved

0x07 = Notify MCU that ASR rebooted; not sent to Cloud

0x08 = Response to local Set; e.g., when a scheduled event fires

0x09 = Reboot

0x0A = Cyclic redundancy check (CRC) failure; used to sync state between device and Cloud when attribute values no longer match

0xAA = Invalid reason; set when the Cloud receives an update with either no reason or an invalid reason

uint16_t Value length
n bytes Variable-length attribute value