BLE Advertisement Format

Bluetooth® Basics: Bluetooth Low Energy uses advertising packets to make data visible before an active connection is established. This page outlines the technical structure of such packets and explains the key fields for beacon and sensor applications.

taskit BLE Manufacturer Advertisement Format

Specification of the manufacturer-specific BLE broadcast packet for taskit products (BLE Sensor & Beacon).

• Basis: [[BLE/BLE Advertisement Format]]
• Source: [[BLE/BcastPacket-Table 1.csv]]
• Company Identifier taskit: 0x017B (Little Endian → 0x7B 0x01)

1. Package structure

The format uses the standard BLE advertising packet (31 bytes), consisting of two AD structures:

1. Flags AD (3 bytes) – always 02 01 06
2. Manufacturer Specific Data AD (variable length) containing the taskit Company ID

┌──────────────┬───────────────────────────────────────────────────────────┐
│  Flags AD    │              Manufacturer Specific Data (0xFF)            │
│              │                                                           │
│  02 01 06    │  [Len] FF  7B 01  [Type] [Version]  [Payload ...]         │
│  3 Bytes     │  variable length (Len = 0x1A or 0x1B, depending on type)  │
└──────────────┴───────────────────────────────────────────────────────────┘

Bytes 1–7 are identical in all taskit variants (except for byte 4: 0x1A without MAC, 0x1B with MAC).

2. Frame types (byte 8)

Byte 8 distinguishes between Anonymous (iBeacon-compatible) and Named (proprietary taskit formats):

Apple iBeacon comparison: Bytes 6/7 = 0x4C 0x00 (Apple), Byte 8 = 0x02, Byte 9 = 0x15. Taskit iBeacon uses exactly the same layout, but with a Company ID of 0x7B 0x01.

3. Complete byte table

The following table shows the complete byte mapping for all 31 bytes across all frame types.

The columns for Blue RTD / Blue Loop RX / Blue Loop TX / Blue pH-Meter are specialisations of Taskit Sensor with MAC (byte 8 = 0x20) and differ only in byte 10 (hardware ID) and byte 11 (SenML unit ID).

4. Sensor payload (type 0x20 / 0x30)

4.1 Hardware ID (Byte 10)

4.2 SenML Unit ID (Byte 11)

According to RFC 8428 SenML Units

4.3 ID field (bytes 12–17, up to 25 if necessary)

• Type 0x20 (sensor with MAC): 6-byte BLE MAC address in bytes 12–17, followed by 8-byte name (bytes 18–25, ASCII)
• Type 0x30 (sensor with RPI): Rotating Proximity Identifier in bytes 12–17 (no additional name)

4.4 Measured value (bytes 28–31)

The measured value is encoded as a 32-bit IEEE 754 float (bytes 28–31). The unit is determined by the SenML Unit ID (byte 11).

Example: Blue RTD at 24.7 °C:
  Value = 24.7 (IEEE 754 single)
       = 0x41 C5 99 9A
  → Bytes 28–31 = 41 C5 99 9A   (byte order according to BLE spec, little-endian)

5. iBeacon Payload (Type 0x02)

Identical to the Apple iBeacon layout, but with a taskit Company ID:

See also: [[BLE/BLE Advertisement Format#5.1 iBeacon (Apple)]]

6. Additional Definitions (from CSV)

These fields are documented separately in the CSV and relate to taskit-specific frame extensions:

6.1 MsgType

Data format of payload bytes 20 to 31 — see the “MsgType” table for details.

→ This byte defines the format of the subsequent payload data.

6.2 BroadcastTime

Bits 7–4: BroadcastInterval   (see table ‘BcastIDs’ for details)
Bits 3–0: BroadcastNumber     (continuously incrementing counter)

→ Allows the recipient to detect packet loss and determine the transmission interval.

6.3 Serial No.

Taskit-unique serial number in Little Endian.

6.4 Data

Format according to MsgType (see 6.1).

These fields supplement the table in Chapter 3; their exact byte position within the MsgType frame is documented in the “MsgType” and “BcastIDs” tables.

7. Complete example package – Blue RTD (24.7 °C)

Advertising Data (31 Bytes):

  02 01 06                              Flags: General Discoverable, BLE only
  1B FF                                 Length=27, Manufacturer Specific Data
       7B 01                            Company ID: taskit GmbH (0x017B, LE)
       20                               Type: Taskit Sensor mit MAC
       01                               Version
       01                               Hardware ID: 1 = Blue RTD
       37                               SenML Unit ID: 55 = Cel (°C)
       AA BB CC DD EE FF                MAC-Adresse (6 B)
       'B' 'R' 'T' 'D' '0' '0' '0' '1'  Name (8 B, ASCII)
       -- --                            (Bytes 26-27 unbelegt)
       41 C5 99 9A                      Value = 24.7 (IEEE 754 single)

8. Complete example package – Taskit iBeacon

Advertising Data (31 Bytes):

  02 01 06                              Flags
  1A FF                                 Length=26, Manufacturer Specific Data
       7B 01                            Company ID: taskit GmbH
       02 15                            iBeacon Type / Length
       F7 82 6D A6 4F A2 4E 98          UUID (16 Bytes)
       80 24 BC 5B 71 E0 89 3E
       00 01                            Major  = 1
       00 2A                            Minor  = 42
       C5                               RSSI   = −59 dBm @ 1 m

9. Version History

Related documents

• BLE/BLE Advertisement Format – General BLE advertising protocol
• BLE/BcastPacket-Tabelle1.csv – Original source (taskit broadcast packet format)
• Measure2Go – Product description
• Beacon Line – Anchor beacon system