7 - Notification Messages Sent from Device to Host (Extended Notifications Only)
eDynamo| Secure Card Reader Authenticator | Programmer’s Manual (COMMANDS)
Page 58 of 245 (
D998200115-17
)
7
Notification Messages Sent from Device to Host (Extended
Notifications Only)
7.1
About Notification Messages
This section provides detail about unsolicited generic notification messages the device sends to the host,
excluding magnetic stripe card data documented separately in section
6 Magnetic Stripe Card Data Sent
. Each subsection is tagged with the features, connection types, and data formats for
which it is relevant.
Notification messages may be split into multiple packets, each containing a portion of the complete
notification message. This allows notification messages to exceed the maximum packet sizes of the
connection type and data format. After the host receives a complete notification message, it will have a
notification identifier, a complete data length, and a complete notification message data field.
How the host interprets incoming packets to find the data detailed in this section depends on the
connection type (see section
) and the data format (see section
). All
packets arrive at the host in the format-dependent structure shown in
. Each incoming packet
. The
notification message
can be interpreted by first assembling all
packets pertaining to the notification message, then looking up the corresponding
Notification Identifier
in the sections that follow.
Table 7-1 - How Notification Message Packets Arrive
Format
Where to Find Value
HID
Report identifier 2, Usage identifier 0x20
Streaming
N/A
TLV
N/A
GATT/SLIP
Similar to card data.
For GATT, see section
2.2.4 How to Receive Data On the Bluetooth LE
and section
3.2 How to Use GATT Format (GATT Only)
Table 7-2 - Structure of Packets That Form a Notification Message
Offset Field Name
Description
0..1
Partial Data
Length
The length of the
Data
field contained in the current message. This field is in
big endian format. If this value is not equal to the
Complete Data Length
, the
device is sending the notification using multiple packets.
2..3
Data Offset
The offset position in bytes within the entire assembled notification where the
first byte of the current packet’s
Data
field is located. This field is in big endian
format. The first byte of the entire notification’s Data is at offset zero.
4..5
Notification
Identifier
The type of notification being sent. This field is in big endian format. The
value corresponds to the notification identifier numbers in the headings of the
subsections of section
7 Notification Messages Sent from Device to Host
. In many cases, two-byte notification identifiers
are assigned such that the high byte indicates a group of related commands, and
the low byte specifies a command within that group.
