How to configure and run zynqGrabber

zynqGrabber is an application that runs on the ZCB or z-turn which forms a bridge between the FPGA (reading events from the sensors), and the YARP network, such that the events can be processed on one or more CPUs or neuromorphic hardware. To run the zynqGrabber:

• the ZCB needs to be running, or connected to, a yarpserver,
• event-driven needs to be installed correctly with zynqGrabber ENABLED, and
• the configuration file needs to be configured for the sensors connected to the hardware.

zynqGrabber configuration file

When event-driven is installed (make install), it installs also the configuration files for the zynqGrabber. However the default values in the file need to be modified depending on the hardware that you want to use.

:warning: We need to make a local copy of the file such that re-installing event-driven won't overwrite your local changes with the default ones!

First of all make an SSH connection to the ZCB. You can modify the local configuration file using:

nano ~/.local/share/yarp/contexts/event-driven/zynqGrabber.ini

If the file/folder do not exist you must first import the local copy from the installed copy. Run the following command to automatically import a local copy of the configurations file and re-try modifying the file:

yarp-config context --import event-driven zynqGrabber.ini

The zynqGrabber has the following options:

• name : renames the ports opened, needed if more than one zynqGrabber is running on the same network
• verbose : print out a little more information on start-up
• aps : turn on the ATIS aps events
• dataDevice : the full path to the device that will be opened to read events
• hpu_read : open a thread to read data from the HPU and publish it to YARP
• hpu_write : open a thread to write data to the HPU device
• packet_size : the maximum number of events to send in a single packet (too small can lead to latency, too large can lead to packet-loss in UDP connections)
• visCtrlLeft : connect to a device to configure the left camera
• visCtrlRight : connect to a device to configure the right camera
• skinCtrl : connect to a device to configure the skin
• use_spinnaker : configure HPU to write to a SpiNNaker device
• [ATIS_BIAS_LEFT] : bias values for the left camera
• [ATIS_BIAS_RIGHT] : bias values for the right camera
• [SKIN_CNFG] : configuration parameters for the skin

Most default values are fine for use of event-driven sensors. However, the hardware you have means that the file will need to be configured.

• Comment out any devices you don't have connected.
• Set use_spinnaker and the HPU device to hpu_read and hpu_write if connected to the SpiNNaker.
• Change the name if this is not the only zynqGrabber on the network

Run the zynqGrabber

Once the configuration has been correctly performed, you can run the zynqGrabber from the terminal:

zynqGrabber

If zynqGrabber doesn't open it should give a warning message stating the problem, typically yarpserver is not running/connected or it is trying to open a device that is not physically connected.

Check the zynqGrabber is streaming data

On your own laptop that has a connection to the ZCB yarpserver you can run:

yarp read ... /zynqGrabber/AE:o

to verify that the data is streaming. The data is not in a human-readable format but it's presence indicates that the zynqGrabber is working.