Measurements#

The following examples use this two-node Bluetooth mesh setup:

• Switch LPN: SLWSTK6023A EFR32xG21 Bluetooth Starter Kit with a main board and radio board running the Bluetooth Mesh - SoC Switch Low Power example. The example has LPN, Proxy (communication with Bluetooth LE devices like the mobile phone connection), and Relay features.

• Light node acting as a Friend node: SLWSTK6023A EFR32xG21 Bluetooth Starter Kit with a radio board running the Bluetooth Mesh – SoC Light example having Friend, Proxy, and Relay features. Also, some other Bluetooth mesh-compatible boards can be used instead of this. See QSG176: Bluetooth® Mesh SDK v2.x Quick-Start Guide for a list of compatible products.

Unprovisioned Low Power Node#

Because the LPN using the Bluetooth Mesh - SoC Switch Low Power application is still unprovisioned, the current measurement should look like the following figure. Be sure to measure the Bluetooth Mesh - SoC Switch Low Power node not the Bluetooth Mesh - SoC Light node.

The current measurement is on a steady high level (average 10.68 mA in the example) because the node is running and waiting for provisioning. When using some a device family other than the EFR32xG21, the current might be different.

Low Power Node Looking for a Friend Node#

Open the Bluetooth mesh mobile application and provision the Bluetooth Mesh - SoC Low Power Switch node. Refer QSG176: Bluetooth® Mesh SDK v2.x Quick-Start Guide for mobile application and provisioning instructions. At this point, provision only the Switch and do not change any Device Configuration settings at this time.

After provisioning, remember to return to the mobile application main level so that the Bluetooth connection with the mobile phone is closed. You should then see a current profile like the following figure.

On average the current measurement is now much lower (3.94 mA in this example). The approximately one second lasting high current part occurs when the LPN is looking for a Friend node by sending Friend Request messages. The lower current part with spikes that takes approximately two seconds occurs when the device is sleeping (no Bluetooth mesh communication) and using the Proxy feature (Bluetooth LE device connectivity).

By changing the parameter LPN_FRIEND_FIND_TIMEOUT it is possible to affect the power consumption when the LPN is looking for a Friend node. The LPN_FRIEND_FIND_TIMEOUT default is two seconds in the example (the part with lower current levels and spikes).

Low Power Node Friendship Established#

Provision Bluetooth Mesh - SoC Light (the Light node) also acting as a Friend node. Now the Switch LPN establishes a friendship with the Light node.

The power measurements look like the following figure.

The current consumption is now only 736 µA on average which is much less than the original over 10 mA measurement.

Low Power Node Friendship Established with Proxy turned Off#

Turn the Proxy off: Turn off the Bluetooth Mesh - SoC Light node to make sure the device is connecting directly to the Bluetooth Mesh - SoC Low Power Switch node. Use the mobile application to connect the network, select the Bluetooth Mesh - SoC Low Power Switch node, refresh the Proxy feature, and then disable it. Also remember to return to the mobile application main level so the Bluetooth connection with the mobile phone is closed. Now turn the Bluetooth Mesh - SoC Light node back on to establish friendship again. The new measurements should look like the following figure.

The current measurement is now only 6.6 µA. There is no communication visible as the poll period (PollTimeout) is so long that it is not detected. A longer—over 120-second measurement—appears in the following figure.

There is now just a little less than 120 seconds between the Friend Polls and the current consumption is 8.5 µA on average. The communication current spike after every about 120 seconds looks like the following figure.

There are two parts in the communication:

• Sleeping time of 119.3 seconds using average current of 6.6 µA.

• Friend Poll: Friend Update that takes about 67 ms and average current is 3.22 mA.

These are a few other examples with different PollTimeout settings:

• 120 seconds PollTimeout: (120 s * 0.0066 mA + 0.067 s * 3.22 mA) / (120 s + 0.067 s) = 8.4 µA (received what was measured which is correct)

• 10 seconds PollTimeout: (10 s * 0.0066 mA + 0.067 s * 3.22 mA) / (10 s + 0.067 s) = 28 µA

• 1 seconds PollTimeout: (1 s * 0.0066 mA + 0.067 s * 3.22 mA) / (1 s + 0.067 s) = 210 µA = 0.21 mA

As Bluetooth mesh uses Bluetooth communication, refer to AN1246: EFR32BG SoC Bluetooth® Smart Device Power Consumption Measurements for more detailed information.