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Not applicable



I want to have streaming on two highspeed ISO endpoints (pkt_size= 3 * 1024) with double buffering. I wrote a firmware using AUTOIN mode and slave fifo and it worked fine with external master (FPGA) when i used packet size 2048(=2*1024). By use of Cypress Screamer with a few modifications, rate of receiving data reaches 31.8 MBps.


but when I use packet size 3072 for endpoints for achieving rate 48 MBps, the ISO transfer failed (using CyConsole).


Is there anybody that has successful transfers using two highspeed ISO endpoints?


Any suggesstion?


Additional information:


I use 2010 CyUSB driver.


I use keil uvision4 for FW and visual studio 2010 (VC#) for APP.


Thank you in advance

3 Replies
Not applicable

Hi again




Some days ago, I created packets using 8051 inside FX2 and in worked. Transfer rate reached 48 MBps.


I think the reason is that, SIE gets data from fifo with rate of 60 MBps and I write to fifo with 48 MBps. So I can not fill fifo in time. When I use High-Speed ISO endpoint with 3 packets per microframe and double buffering, it is obvious that transmission fails.


I think there is no way to use FX2 with two High-Speed ISO EPs with double buffering for each of them.


If you have any opinion about it, let me know please.



 Did you resolved the problem?

Not applicable

60MBps is the theoretical speed. When you say 48MHz you are assuming clocking in a byte every clock cycle on the GPIF/Slave FIFO. FX2LP can go upto 2bytes per clock cycle if you use all 16 data lines. i.e. 92MBps which is greater than what USB protocol can offer. so FX2LP is capable of offering your speed requirement.