Coefficients load to FIR or FIR2 filters slowly when using an USB interface

Tech Note: TN0171
Product: RPvdsEx
Version: All
Date Added: 2005-03-10


Loading a large number of coefficients to an FIR or FIR2 filter can take several seconds when using a USB PC-to-zBus interface. Because coefficient values are loaded to data memory, which does not support block read and writes, values must be loaded from the PC to data memory one value at a time. When using a USB interface this can take between 1 (USB 2.0) and 5 (USB 1.1) milliseconds for each write. Coefficients on the order of 1000 points can take over a second to load.


If the upload is too slow, consider using a Gigabit interface, which can improve the transfer rate by 40 times.