Bluetooth 4.0: Low Energy

Use Cases

• Proximity.

• Time.

• Emergency.

• Network availability.

• Personal User Interface.

• Simple remote control.

• Browse over Bluetooth.

• Temperature Sensor.

• Humidity Sensor.

• HVAC.

• Generic I/O (automation).

• Battery status.

• Heart rate monitor.

• Physical activity monitor.

• Blood glucose monitor.

• Cycling sensors.

• Pulse Oximeter.

• Body thermometer.

Short range wireless application areas

How much energy does traditional Bluetooth use?

Traditional Bluetooth is connection oriented. When a device is connected, a link is maintained, even if there is no data flowing.

Sniff modes allow devices to sleep, reducing power consumption to give months of battery life.

Peak transmit current is typically around 25mA.

Even though it has been independently shown to be lower power than other radio standards, it is still not low enough power for coin cells and energy harvesting applications.

What is Bluetooth Low Energy?

Bluetooth low energy is a open, short range radio technology.

• Blank sheet of paper design.

• Different to Bluetooth classic (BR/EDR).

• Optimized for ultra low power.

• Enable coin cell battery use cases.

  • < 20mA peak current.

  • < 5 uA average current.

Basic Concepts

Everything is optimized for lowest power consumption.

• Short packets reduce TX peak current.

• Short packets reduce RX time.

• Less RF channels to improve discovery and connection time.

• Simple state machine.

• Single protocol.

• Etc.

Factsheet

Designed for exposing state

Data Throughput.

• Data throughput is not a meaningful parameter. It does not support streaming.

• Data rate (typical) = 1Mbps, but is not optimized for file transfer.

• Designed for sending small chunks of data (exposing state).

  • It’s good at small, discrete data transfers.

  • Data can triggered by local events.

  • Data can be read at any time by a client.

  • Interface model is very simple (GATT).

Architecture