GATT Profiles — Health Thermometer, Blood Pressure & BLE IoT with IPSP
Chapter 15 · Part 2 of 2 · Sections 15.10–15.16.4 · CTS · HTS · HTP · BPS · BLP · Sports Profiles · IPSP · IPv6 · 6LoWPAN
Distributes the current time from a time-aware device (phone, tablet, NTP-synced gateway) to simpler devices that do not keep their own reliable clock. A practical example is a smartwatch that stays time-correct when a user travels across time zones — the phone writes the updated time and timezone offset to the watch automatically.
Delivers temperature readings from a thermometer to a collector. The service is designed for healthcare and fitness applications where the collector needs both final temperature values and intermediate readings during the measurement process.
/* Enable Temperature Measurement Indications: */
/* Find CCCD handle after char 0x2A1C: */
gatttool -b AA:BB:CC:DD:EE:FF --char-desc \
--start=0x000b --end=0x0013
/* Find descriptor uuid:0x2902 → write 0x0200 to enable ind */
gatttool -b AA:BB:CC:DD:EE:FF \
--char-write-req --handle=0x000d --value=0200
/* Enable Intermediate Temperature Notifications: */
/* Find CCCD for 0x2A1E → write 0x0100 to enable notify */
gatttool -b AA:BB:CC:DD:EE:FF \
--char-write-req --handle=0x0012 --value=0100Performs the temperature measurement, exposes HTS and DIS. Implements GAP Peripheral role. Both HTS and DIS are mandatory.
Receives temperature data from the Thermometer. Implements GAP Central role. Typically a mobile phone, tablet, or medical gateway.
Delivers blood pressure readings including systolic pressure, diastolic pressure, and optionally pulse rate. Uses Indication for final readings (must be confirmed) and Notification for intermediate cuff pressure values during inflation.
Measures blood pressure, exposes BPS and DIS. GAP Peripheral role. Both services are mandatory.
Receives blood pressure data. GAP Central role — typically a phone or clinical monitoring device.
15.15 — Health, Sports and Fitness Profiles
Additional Profiles Using the Same GATT Pattern
These profiles all follow the same architecture as HTP and BLP — a sensor acting as GATT Server/GAP Peripheral, a collector as GATT Client/GAP Central, and one or two services with a small set of characteristics.
| Profile / Service | UUID | What It Does |
|---|---|---|
| Glucose Service (GLS) | 0x1808 | Glucose concentration, meal context, sensor status from a glucose meter |
| Glucose Profile (GLP) | — | Collector interacts with a glucose sensor using GLS |
| Heart Rate Service (HRS) | 0x180D | Heart rate measurement, body sensor location, energy expended, RR-intervals |
| Heart Rate Profile (HRP) | — | Collector interacts with a heart rate sensor using HRS |
| Cycling Speed & Cadence Service (CSCS) | 0x1816 | Wheel revolution data, crank revolution data for cycling computers |
| Cycling Speed & Cadence Profile (CSCP) | — | Collector interacts with a cycling sensor using CSCS |
/* Heart Rate Measurement — subscribe to notifications: */
/* HRS UUID 0x180D → HR Measurement char UUID 0x2A37 */
/* Properties = 0x10 (Notify only) */
/* Find HRS: */
gatttool -b AA:BB:CC:DD:EE:FF --primary --uuid=0x180D
/* Find HR Measurement characteristic: */
gatttool -b AA:BB:CC:DD:EE:FF \
--characteristics --uuid=0x2A37
/* Enable notifications (write 0x0001 to CCCD): */
gatttool -b AA:BB:CC:DD:EE:FF \
--char-write-req --handle=0x000d --value=0100
/* Receive heart rate values continuously: */
gatttool -b AA:BB:CC:DD:EE:FF --listen15.16 — Internet Protocol Support Profile (IPSP)
IPv6 Packets Over BLE — Making Sensors Part of the Internet
IPSP was introduced in BLE Specification 4.1 to bring IoT devices directly onto the Internet without intermediate protocol conversion. A BLE sensor running IPSP generates standard IPv6 packets. A smartphone acting as a BLE router forwards these packets onto the internet. Because they are already IPv6, the router performs minimal processing — it just routes them, it does not translate them.
The full specification for IPv6 over BLE transport is RFC 7668. IPSP also relies on RFC 4861 (IPv6 Neighbor Discovery) and RFC 6775 (6LoWPAN-optimised Neighbor Discovery).
What Is IPv6 and Why BLE Needs It
IPv4 addresses are 32 bits long — theoretically 4.3 billion addresses. In practice far fewer are usable because some ranges are reserved and others were allocated to organisations without being deployed. With billions of IoT devices being added each year, IPv4 exhaustion is a real problem.
IPv6 addresses are 128 bits long. This gives approximately 3.4 × 1038 unique addresses — enough to assign a unique address to every sensor, every actuator, every device on the planet many times over. A typical IPv6 address looks like: 2001:0DB8:D3F0:0123:4567:89AB:CDEF:0001
For IPSP, each BLE device derives its 128-bit IPv6 address from its 48-bit BD_ADDR using a deterministic mapping, so no external address assignment is needed.
What Is 6LoWPAN
6LoWPAN stands for IPv6 over Low-power Wireless Personal Area Networks. IPv6 packets can be up to 65,535 bytes. BLE’s default L2CAP MTU is much smaller. 6LoWPAN solves this mismatch by:
6LoWPAN was originally defined for IEEE 802.15.4 networks but applies equally to BLE. RFC 7668 defines the mapping for BLE specifically.
IPSP Roles: Node and Router
Generates or consumes IPv6 packets. Runs the Internet Protocol Support Service (IPSS) so routers can discover it via GATT. Typically a BLE sensor (blood pressure monitor, thermometer, smart shoe). Usually the GAP Peripheral.
Routes IPv6 packets between the BLE network and the internet (or other IP networks). Performs minimal packet processing. Typically a smartphone or home gateway. Usually the GAP Central.
Sensor (6LN)
(6LN)
(6LN)
The 6LBR does not have to be connected to the internet. The 6LN devices and the 6LBR can form a private subnet — for example, a set of wearable devices communicating with each other through a smartphone hub without any external connectivity.
The Internet Protocol Support Service (IPSS) runs on the Node device and allows Routers to discover it using standard GATT service discovery. The service itself has no characteristics — its presence alone signals that this device supports IPv6 over BLE.
15.16.4 — IPv6 Discovery Operations Over BLE
Standard IPv6 Messages Used for Network Setup
After the BLE connection is established and the IPSP L2CAP channel is set up, the node and router use standard IPv6 Neighbor Discovery Protocol (NDP) messages to configure the network. These are the same messages used in any IPv6 network — IPSP does not invent new protocols, it just carries standard IPv6 over BLE transport.
/* Test IPSP connectivity with Ping once IPv6 link is up: */
ping6 -I hci0 fe80::xxxx:xxxx:xxxx:xxxx
/* Linux kernel 3.16+ supports 6LoWPAN BLE via BlueZ: */
/* Load the 6LoWPAN module: */
sudo modprobe bluetooth_6lowpan
/* Enable 6LoWPAN on BLE interface: */
echo 1 > /sys/kernel/debug/bluetooth/hci0/6lowpan_enable
/* Connect to a 6LN node (public address): */
echo "connect AA:BB:CC:DD:EE:FF 0" > \
/sys/kernel/debug/bluetooth/hci0/6lowpan_control
/* Check IPv6 interface created: */
ip -6 addr show bt0
/* inet6 fe80::xxxx:xxxx:xxxx:xxxx/64 scope link */
/* Neighbour advertisement visible in: */
tcpdump -i bt0 icmp6Chapter 15 Summary — GATT-Based Profiles in Practice
GATT-based profiles demonstrate the power of the GATT model. Each profile is small and focused because all the complexity — discovery, read/write access, notification infrastructure — is already handled by ATT and GATT. A profile only has to define what data to expose.
The profiles in this chapter span the most common BLE use cases: proximity and alerting (IAS, FMP, LLS, TPS, PXP), device management (BAS, DIS), time distribution (CTS), healthcare (HTS, HTP, BPS, BLP, GLS, HRS), sports (CSCS, CSCP), and IoT networking (IPSP). All of them run on the same foundation built across Chapters 12, 13, and 14.