FlockLab 2 Services

A detailed description of the services can be found in our paper.

Reprogramming & Power Supply

Refer to the XML configuration.

Serial Service (Logging & Forwarding):

The serial service works both ways: a node can send data to an observer, but you can also send data to the node. For every observer used in a test, a TCP port is opened on the FlockLab server for the time the test is running. You can connect to the ports using appropriate tools (e.g. nc or ncat). You can then send data to the node and you will also receive everything that the node sends over its serial interface. In the test results file for the serial service, all data that you send to the node will be denoted with a w, data sent by the node will be denoted with an r. Note that only one connection can be made to any observer and that access to the port is restricted to the IP address specified in the test XML configuration. The ports opened on the FlockLab server are calculated as:

TCP Port = 50100 + ObserverID

You can thus connect to e.g. Observer 10 using nc by issuing the following command:

nc flocklab.ethz.ch 50110

GPIO Tracing

Refer to the XML configuration.

Sampling rate: 10MHz
Accuracy (GNSS synchronization): ~250ns
Accuracy (PTP synchronization): ~3us

GPIO Actuation

Refer to the XML configuration.

Power Profiling

Refer to the XML configuration.

Debugging Service

Refer to the XML configuration.

Time synchronization

The observers are time-synchronized either via a GNSS receiver or PTP.
Details can be found on the observer status page.

Current Limitations

• GPIO tracing may be partially unavailable due to issues with the time synchronization. The synchronization status of all observers is monitored on this page.
• Time synchronization on observers that are synced via the network (PTP) can occasionally be off by tens of microseconds due to changing CPU load on the observer or high network traffic.
• The accuracy of the GPIO actuation service is in the order of tens of microseconds due to uncertainties in the task execution timing on the observer system (Linux kernel).

FlockLab 2 High-Level System Overview