7 Event handling - AWS IoT ExpressLink
7.1 Introduction7.2 Event handling commands7.3 Diagnostic commands

7 Event handling

7.1 Introduction

Events are generated by internal or external occurrences that require the host controller's attention, such as the arrival of messages on one of the subscribed topics, but also error conditions that reflect an unexpected change in the module's internal state.

Events are appended to the module event queue. From there the host can fetch them in order of arrival (FIFO) by polling the event queue periodically (at regular intervals), or, if the EVENT pin is connected, after detecting a (rising edge) signal on the pin.

7.1.1.1   The event queue depth is an implementation dependent parameter that must be documented by the vendor in the module datasheet.

7.1.1.2   The EVENT pin is asserted (HIGH) when the event queue contains one or more events. The EVENT pin is automatically de-asserted as soon as the host processor has emptied the event queue.

7.1.1.3   When the event queue is full, and a new event occurs, the oldest event is discarded (circular buffer).

7.2 Event handling commands

7.2.1 EVENT?   »Request the next event in the queue«

Returns:
7.2.1.1   OK [{event_identifier} {parameter} {mnemonic [detail]}]{EOL}

When the queue contains one or more events, the module response returns the first event in order of arrival (FIFO). See Table 4 below for the predefined event types.

7.2.1.2   OK{EOL}

If the event queue is empty, then the 'OK' response is followed immediately by {EOL}.

The following table contains the definition of common event identifiers and error codes implemented by all ExpressLink modules; they should be considered reserved:

Table 4 - ExpressLink event codes

Event Identifier

Parameter

Mnemonic

Description

1

Topic Index

MSG

A message was received on the topic #.

2

0

STARTUP

The module has entered the active state.

3

0

CONLOST

Connection unexpectedly lost.

4

0

OVERRUN

Receive buffer Overrun (topic in detail).

5

0

OTA

OTA event (see the OTA? command for details).

6

Connection Hint

CONNECT

A connection was established or failed.

7

0

CONFMODE

CONFMODE exit with success.

8

Topic Index

SUBACK

A subscription was accepted.

9

Topic Index

SUBNACK

A subscription was rejected.

10

Topic Index

PUBACK

A QoS1 PUBACK was received.

11..19

-

-

RESERVED

20

Shadow Index

SHADOW INIT

Shadow[Shadow Index] interface was initialized successfully.

21

Shadow Index

SHADOW INIT FAILED

The SHADOW[Shadow Index] interface initialization failed.

22

Shadow Index

SHADOW DOC

A Shadow document was received.

23

Shadow Index

SHADOW UPDATE

A Shadow update result was received.

24

Shadow Index

SHADOW DELTA

A Shadow delta update was received.

25

Shadow Index

SHADOW DELETE

A Shadow delete result was received.

26

Shadow Index

SHADOW SUBACK

A Shadow delta subscription was accepted.

27

Shadow Index

SHADOW SUBNACK

A Shadow delta subscription was rejected.

28...39

-

-

RESERVED

40

0

BLE CONNECTED

A BLE Connection was established peripheral role.

41

0 or Hint Code

BLE DISCOVER COMPLETE

0 for successful; >0 vendor defined Hint Codes.

42

0 or Central Index

BLE CONNECTION LOST

Connection was terminated or 0 if peripheral role.

43

GATT Index

BLE SUBSCRIBE START

Subscription started on BLEGATT# while on peripheral mode.

44

GATT Index

BLE SUBSCRIBE STOP

Subscription terminated on BLEGATT# while on peripheral mode.

45

GATT Index

BLE READ REQUEST

Read operation requested at BLEGATT# while on peripheral mode.

46

GATT Index

BLE WRITE REQUEST

Write operation requested at BLEGatt# while on peripheral mode.

47

Subscription Index

SUBSCRIPTION RECEIVED

Subscription was received on BLECentral# connection.

≤ 999

-

RESERVED.

≥1000

-

Available for custom implementation.

7.2.1.3   Sleep, reset, and factory reset commands automatically clear all events pending.

7.3 Diagnostic commands

7.3.1 DIAG {command} [optional parameters]   »Perform a diagnostic command«

A number of custom diagnostic commands can be added to assist the developer in their debugging efforts. These commands are vendor and model specific. See the manufacturer's datasheet for specific details.

Example 1:

AT+DIAG PING xxx.xxx.xxx.xxx    # Initiate a Ping of the IP address provided

Example 2:

AT+DIAG SCAN seconds    # Initiates a SCAN of nearby Wi-Fi access points with a timeout