Expected completion time of this lab:

40 min

The latency with the default settings is on the order of 1 second per hop. While this allows for excellent power consumption, for some applications, this is too slow. In this part, we will explore the range of achievable latencies, by using the LEDPing sample application.

The LEDPing application interacts with a mote in master mode, using OAP. It sends a command to set the LED on, waits for an indication that the change was done, sends a command to set the LED off, etc.

Without backbone mode

Start the LEDPing application, and connect to the manager.
Enter the MAC address of the mote in the text field, then press start.
Using a stopwatch, what is the time it takes for the LED to switch ON 10 times?
What is the average RTT of the network (round-trip time)?

With backbone mode

"Backbone" is a mode where all cells of the communication schedule are scheduled. This yields very low latencies, at the cost of an increased power consumption.

On the manager’s CLI, enter:
> login user > show config
What is the value of bbmode parameter?

Enter the following commands:

> set config bbmode 2
> set config bbsize 2

Power cycle both the manager and the mote. Wait for the mote to join.
Repeat the measurements above. What is the RTT now?