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Get started with BLE
BLE reference
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
48
This API reference assumes that you are familiar with Bluetooth and GATT services. The specifications
for Bluetooth are an open standard and can be found at the following links:
n
Bluetooth Core Specifications:
https://www.bluetooth.com/specifications/bluetooth-core-
n
Bluetooth GATT:
https://www.bluetooth.com/specifications/gatt/generic-attributes-overview
The XBee API GATT Service contains two characteristics: the API Request characteristic and the API
Response characteristic. The UUIDs for the service and its characteristics are listed in the table
below.
Characteristic
UUID
API Service UUID
53da53b9-0447-425a-b9ea-9837505eb59a
API Request Characteristic UUID
7dddca00-3e05-4651-9254-44074792c590
API Response Characteristic UUID
f9279ee9-2cd0-410c-81cc-adf11e4e5aea
API Request characteristic
UUID
: 7dddca00-3e05-4651-9254-44074792c590
Permissions
: Writeable
XBee API frames are broken into chunks and transmitted sequentially to the request characteristic
using write operations. Valid frames will then be processed and the result will be returned through
indications on the response characteristic.
API frames do not need to be written completely in a single write operation to the request
characteristic. In fact, Bluetooth limits the size of a written value to 3 bytes smaller than the
configured MTU (Maximum Transmission Unit), which defaults to 23, meaning that by default, you can
only write 20 bytes at a time.
After connecting, you must send a valid
in order to authenticate the
connection. If the Bluetooth Unlock API Frame has not been executed, all other API frames will be
silently ignored and not processed.
API Response characteristic
UUID
: f9279ee9-2cd0-410c-81cc-adf11e4e5aea
Permissions
: Readable, Indicate
Responses to API requests made to the request characteristic will be returned through the response
characteristics. This characteristic cannot be read directly.
Response data will be presented through indications on this characteristic. Indications are
acknowledged and re-transmitted at the BLE link layer and application layer and provides a robust
transport for this data.