FinishDataXfer returns blocks of zeros when using isochronous data transfer

[jowac_1171871]

I'm sending a test pattern (ramp) from an FPGA using the GPIF data bus to the FX3.

The data arrives fine, but when I read the data from my Windows application there are big blocks of zeros in the data, as seen in the picture below.

What could be causing this?

I can't see any zeros added on the FPGA side.

I expect that the read length returned from FinishDataXfer should make sure that that part of the buffer should contain valid data.

[Rashi_Vatsa · Accepted solution]

Hello,

Please probe the USB lines using Wireshark and share the traces. From this, we will get to know if zero data is read by FX3 or if is it due to an isochronous endpoint bandwidth mismatch. Please let me know the isochronous endpoint configurations in the firmware

Please refer to this KBA with configuration details  Change Bulk endpoint to Isochronous in FX3 firmwar... - Infineon Developer Community