OpenNAS wizard quick view
Once OpenNAS tool has been executed and the Welcome screen appears, the user only needs to complete the five steps of the OpenNAS wizard to obtain the generated VHDL files. The welcome screen shows a brief text with information about our research group.
Click on the "Next" button to move forward to the next step of the wizard.
The first step allows the user to select the NAS common settings, which are the target FPGA chip and its clock frequency, if the NAS is MONO or STEREO, and the number of frequency channels (or bands). A picture of the FPGA-based board selected is shown to the user to quickly identify the hardware.
In this step, the input audio source must be selected. There are several options, among which we can find the AC'97 audio codec, a pair of Pulse Density Modulation (PDM) microphones, and an I2S-based audio codec. Each input option has its own configuration parameters, which the user can set according to its project requirements.
NAS processing architecture is defined in step 3, where the user can choose either a cascade or parallel architecture. Besides, the order of the filters and the filters output attenuation can be set. Finally, the user can define a frequency range in which the NAS will work, which is set by default as the human audible sounds range (from 20Hz to 22KHz).
The output interface is selected in the fourth step. As in the most of the event-based neuromorphic devices, the AER protocol is used as output. For this reason, the AER monitor is used as output interface by default in order to connect our neuromorphic sensor to jAER which lets us visualize the NAS output in real-time. However, it is also interesting to connect the NAS output to other neuromorphic hardware, as the SpiNNaker board, in which Spiking Neural Networks (SNN) can be deployed and they could use the output from the NAS as input to the network.
Finally, when all previous steps have been done, the destination folder in which the VHDL files are going to be generated has to be selected by the user.
A new message will appear if the generation process was done successfully, indicating the destination folder. Click on the Ok button to close the message. At this point, the process of the NAS generation has finished. Navigating to the destination folder, the user can find all the VHDL files needed to synthesize and generate the NAS .bit file and run it using an FPGA. Apart from VHDL files, OpenNAS also generates an XML file summarizing the parameters selection made by the user.
