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Some questions on using XferData() API call with Isochronous IN Endpoints | Cypress Semiconductor

Some questions on using XferData() API call with Isochronous IN Endpoints

Summary: 1 Reply, Latest post by Bob Marlowe on 23 Nov 2014 09:50 AM PST
Verified Answers: 0
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Manuj's picture
7 posts

 I am using CY8CKIT-050 PSoC 5LP development kit, connected to a Windows 8 PC through Full Speed USB 2.0. Can somebody help me in understanding how the 'XferData(buf, bufLen, pktInfos)' API call works for Isochronous IN endpoints?


1. Cypress CyAPI Programmer's Reference manual (2011) mentions on page 8 that the XferData() call is overloaded to take an additional argument 'pktMode'. If pktMode is true, then the partial data transfer is enabled at an IN end point. However, when I used this call for an ISOC IN Endpoint with pktMode = true, then the compiler gives an error saying 'Too many arguments in function call'. Does this parameter valid for ISOC IN EPs? If yes, then how to use 'pktMode' argument in XferData() call for ISOC IN EP?


2. I have configured an ISOC IN EP with maximum packet size of 1023 bytes and DMA transfer with Automatic Memory Management. I have set the end point transfer size for this EP as 8184 bytes (8 times 1023) using SetXferSize() call. Now, while using 'XferData(buf, bufLen, pktInfos)' API call with this EP in host application:

(i) Should the buffer ('buf') size, and 'bufLen' value be always 8184 bytes (8 times 1023)? Or, should the  'bufLen' value must be equal to maximum packet size (1023)?

(ii) Can we use 'bufLen' value less than 8184, while keeping the buffer size still to be 8184 (For example, in cases when we want to receive less than 8184 bytes)?

(CyAPI manual says that bufLen should be 8 times the maximum packet size, but  I suspect that I am receiving excess data in host application on doing so.)


user_1377889's picture
9307 posts

You are here in USB Controllers forum, I would suggest you to open a thread in PSoC5 forum and place a link to this post. That will ensure that some more of the guys will answer to you.



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