8.2.2 Microchip OTAU Profile

The Bluetooth Low Energy OTAU profile is a GATT-based profile. It is designed to perform device firmware updates via OTA. In general, the mobile acts as the OTAU client role and the Bluetooth Low Energy device as the OTAU server role. OTAU Service (OTAS) is a Microchip proprietary service with a 16-byte service UUID, and it is mandatory for the OTA server.

There must be only one instance of the OTAS in a device. The OTAS must be instantiated as a primary service.

The service Universally Unique Identifier (UUID) value must be set to 4D434850-253D-46B3-9923-E61B8E8215D7.

There are three characteristics defined under the service.

Table 8-1. OTAU Characteristics UUID
Characteristic NameUniversally Unique Identifier (UUID)
OTA Feature4D434850-22E4-4246-AF03-0C4A2F906358
OTA Data4D434850-34D9-40A6-BA7E-56F57C8CD478
OTA Control Point4D434850-9327-45DE-8882-C97F39028A76
Table 8-2. OTAU Characteristics Definition
Characteristic NameRequirementMandatory PropertiesOptional PropertiesSecurity Permissions
OTA FeatureMReadNoneEncryption required
OTA DataMWrite Without Response, NotifyNoneEncryption required
OTA control pointMWrite, NotifyNoneEncryption required
  1. OTAU feature characteristics – Use it to expose the supported image type to the device. Its content carries the supported image type:
    • Firmware image
    • Meta data
    Property: Write
  2. OTAU data characteristics – Allows the OTAU client to send upgradable image data to the OTAU server.

    Properties:

    • Write
    • WithoutResponse
    • Notify
  3. OTAU control point – The OTAU client uses it to issue the operational requests to the OTAU server. Notification of this control point is used by the server to perform a dedicated operation. The operation includes the following:
    • Firmware update request
    • Firmware update start
    • Firmware update complete
    • Device reset request

    Properties:

    • Write
    • Notify