Data loss in isochronous end point

Hi..

I have implemented a GPIF II interface using an FPGA spartan 6 (XC6SLX9) and a Cypress FX3 (CYUSB3013) controller.

An Isochronous USB endpoint is configured to trasfer the data from the Cypress FX3 to a host PC.

The average data generate rate of the FPGA is about 75Mbps which is generated as distributed chunks rather than as a constant rate data stream. However, I am losing a significant amount of data at the host PC allication.

Followng are some details on my sytsem setup.

PCLK = 60Mhz ; (PCLK is driven by FPGA)

FX3 system clock = 403.2 Mhz; (setSysClk400 = true)

GPIF clock = 100 Mhz ; (pibClock.clkDiv = 4)

USB end point type :- Isochronous

*FX3 Firmware

CY_FX_ISO_BURST   = 15;

CY_FX_ISO_PKTS    = 1;

epcfg.enable = CyTrue;

epcfg.epType = CY_U3P_USB_EP_ISO;

epcfg.burstLen = CY_FX_ISO_BURST;

epcfg.streams = 0;

epcfg.pcktSize = 1024;

epcfg.isoPkts = 1;

dma_cfg.size = ((1024 + 0x0F) & ~0x0F);

    dma_cfg.size  *= CY_FX_ISO_BURST;

    dma_cfg.count = 8;

    dma_cfg.prodSckId = CY_U3P_PIB_SOCKET_0;

    dma_cfg.consSckId = CY_U3P_UIB_SOCKET_CONS_2;

    dma_cfg.dmaMode = CY_U3P_DMA_MODE_BYTE;

dma_cfg.notification = CY_U3P_DMA_CB_CONS_EVENT;

dma_cfg.cb = 0;

dma_cfg.prodHeader = 0;

dma_cfg.prodFooter = 0;

dma_cfg.consHeader = 0;

dma_cfg.prodAvailCount = 0;

<ENDPOINT>

Type="ISOC"

Direction="IN"

Address="82h"

Attributes="01h"

MaxPktSize="15360"

DescriptorType="5"

DescriptorLength="7"

Interval="4"

<SUPER SPEED ENDPOINT COMPANION>

Type="SUPERSPEED_USB_ENDPOINT_COMPANION"

MaxBurst="14"

Attributes="00h"

BytesPerInterval="3C00h"

</ENDPOINT>

*PC application code to read usb

LONG length = 1024 * 15 * 8 * 64;

std::shared_ptr<uint8_t> image_buffer = std::shared_ptr<uint8_t>(new uint8_t[length]);

QueueSize = int(length / (iso_ep->MaxPktSize * 8));

if ((length % (iso_ep->MaxPktSize * 8)) > 0)

QueueSize++;

for (int j = 0; j < QueueSize; j++){

long len = length / (QueueSize);

std::unique_ptr<uint8_t[]> image_data = std::unique_ptr<uint8_t[]>(new uint8_t[len]);

iso_ep->TimeOut = 5000;

int pkts;

CCyIsoPktInfo * pktInfos;

pktInfos = iso_ep->CreatePktInfos(len, pkts);

if (iso_ep->XferData(image_data.get(), len, pktInfos)){

for (int i = 0; i < pkts; i++){

if (pktInfos[i].Status == 0 && pktInfos[i].Length>0)

{

memcpy(&image_buffer[success * iso_ep->MaxPktSize], &image_data[i * iso_ep->MaxPktSize], iso_ep->MaxPktSize);

success = success + 1;

}

}

}

delete[] pktInfos;

}

length = success * iso_ep->MaxPktSize;