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Hello, I am using a PSoC 4200L CY8C4246AZI-L433 in a USB application. We have been shipping this product out for almost a year now and it has been working great. Recently, our customer has encountered problems with some units in which the USB interface stops working. I evaluated this issue for a couple of months now and I managed to capture the failure using a USB protocol analyzer. What I found is that the USB host is continuously initiating USB Input transactions and the PSoC keeps responding with a NAK, since it has no data to send. However, at some point in time, the host initiates another Input transaction and the PSoC simply stops responding. The host keeps sending the Input transactions but, the PSoC will no longer respond. I did verify that the PSoC is still operating properly. The transactions from the host are happening pretty fast, is it possible that the PSoC is unable to keep up with the transactions? I could go into a long description of all the things that I tested but, all that accomplished was to prove what it is not the cause. One thing that I will say is that if you put a high-speed hub in between, the problem goes away however, a full-speed hub does not fix it. Any help would be greatly appreciated.
Solved! Go to Solution.
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PSoC 4 Architecture
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Yes, when data is transferring in both directions , it will be included in calculation of transfer rate.
Full speed device can have Maximum Effective Data Rate as 1.2 MB/s only as told in this AN too (page#11):
http://www.cypress.com/file/134171/download
Full speed can devices can't handle data transfer rate higher than that and can NACK.
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PSoC4L support only Full Speed transfer a maximum of around 1 Mega Byte/Second.So, please ensure that the transfer rate is not above the limit.
Can you share the Protocol analyzer log and the Creator project.
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Hi anks,
Thank you for getting back to me so quickly.
When calculating the transfer rate, would you include the data in both directions? If yes, it looks like 8 Bytes are transferred over a period of around 5.4uS, which would give a transfer rate of 1.48Mbyte/S…unless I am missing something.
I attached a text file of the captured data around the time that it failed. The first IN transaction that gets no NAK is packet number 12833715.
Thanks,
Randy Mauger
RLC Electronic Systems
10 Corporate Blvd
Sinking Spring, PA 19608
Ph: (610) 898-4902 x1215
Fx: (610) 898-4903
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Yes, when data is transferring in both directions , it will be included in calculation of transfer rate.
Full speed device can have Maximum Effective Data Rate as 1.2 MB/s only as told in this AN too (page#11):
http://www.cypress.com/file/134171/download
Full speed can devices can't handle data transfer rate higher than that and can NACK.