Stream data from XEM7310

#1

Hello,
I have an application in which I need to continuously stream data from the FPGA to the PC. My desired throughput is 200MBps. The application runs on windows.

Since I started using the front panel API lately, I’m trying to implement a sandbox application to verify which implementation I should use in order not to lose data.
At the moment I have a 65536 32bit words FIFO in the FPGA which is filled with data ramping from 0 to 0xFFFFFFFF at 50MHz. On the PC side I’m continuously reading the data with ReadFromBlockPipeOut, where block size is 16384 and transfer size is 1048576.
It seems there are no real performance problems, in the sense that the PC receives around 1GB of data every 5 seconds. However, if I check the received data I see that once in a while there is a gap in the expected ramp, and overall I lose about 1-2% of the data.

My best guess is that, since the FIFO fills in about 1.3ms, the OS might let it fill completely if it misses a read for more than 1ms which doesn’t seem impossible, so my next try would be to use the DDR RAM on the board in place of the FIFO in order to better buffer the data.
Does anyone have a better solution or sees any problem with what I’m doing?

Thank you in advance for your help

#2

Yes, the system can easily overrun the FIFO memory on the FPGA due if it’s not consumed at the same rate (or faster) than the PC can fill it.

One option is to use BlockThrottledPipes, but this should only be used with caution as to avoid timeout conditions.

The other, as you mentioned, is to use the DRAM as an extended FIFO. Our EVB100X Developer’s Release provides a good example of setting this up in both hardware and software. The source code is available for purchase through our online store.

#3

Thanks for the quick reply.
Actually, I’m already using a block throttled pipe.
I’ll try implementing solution 2 myself and evaluate EVB100X purchase if I get stuck. For now I just wanted to make sure I’m on the right track.

Bests

#4

Hello, finally after a long period I’m back on this problem. I haven’t tried to use the DRAM to buffer data yet, but my boss says it can be ok to spend a few hundred bucks if this can speed the development up a bit. However, before proceeding with the purchase, I wanted to be sure that the source code provided with the EVB boards does solve our problem.
Is there any kind of money back guarantee? Otherwise, would it be possible to get a test bitstream file that does what I described in the orginal post, outputting unsigned 32bit integers from 0 to 0xFFFFFFFF again and again at 50MHz, so that I can test it and verify I do not lose any data on a continuous stream?

Moreover, I see the EVB boards include a camera, but I don’t see a real use for that for my company, we’d basically buy the camera module just for a piece of code, which is acceptable but not optimal. Is there any other module that comes with the same code examples but maybe with other HW devices, like a thermal camera or something else? You know, just to make the most out of our money.

Thanks for the support!

Best regards