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USB Low-Full-High Speed Peripherals

hankchu
New Contributor II

Dear Sir:

    1) We found the KBA as follows"

     1-1)  Reduce Delay Observed During I2C Read Operations In USB-Serial – KBA227320

    https://community.cypress.com/t5/Knowledge-Base-Articles/Reduce-Delay-Observed-During-I2C-Read-O...

    1-1-1)  In the KBA, it said:

This will reduce the observed delay between the APIs to the order of thousands of microseconds, which is significantly less than that produced with the cyusbserial.dll file present in the USB-Serial SDK.

   1-1-2) The solution is for Windows OS (*.dll) and there are not the source codes in the attachment.

   2) We used the Cypress CY7C65211 on our products as the USB-to-I2C Master on Linux OS (x86_64 CPU).

   2-1)  We wish to port the solution to the Linux driver to enhance the I2C performance.

 

   2-2) Could you send us the source codes of the solution or the patches?

            In order to let us port the codes into the Linux driver to enhance I2C performance.

 

  Thank you.

Best Regards.

 

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1 Solution
Meghavi
Moderator
Moderator

Hi,

Slower I2C reads in Windows was due to delay introduced in library API implementation. Refer to this thread for more details - https://community.cypress.com/t5/USB-Low-Full-High-Speed/CY7C65211-USB-Serial-SDK-Long-delays-betwee... 

I2C Read API in library for Linux does not contain any such delays and should work without issues. Can you please test this at your end and let me know if you find similar delay in Linux?

Regards

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Meghavi
Moderator
Moderator

Hi

Can you please provide I2C traces for the case in which you are seeing this delay in linux?

Regards 

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hankchu
New Contributor II

Dear  Meghavi:

   We did not meaure the I2C bus and trace the I2C codes for the delay in Linux.

 

   Our customer asked us to tune the performance of USB-to-I2C application (Cypress CY7C65211).

   And they passed us the URL link of the KBA above.

 

   So, we tried to get the source codes of the solution or the patches on Windows OS.

   In order to port to Linux driver  for the enhancement of the performance (USB-to-I2C).

 

   Could you send us the patches of the solution on Windows OS?

   Thank you.

Best Regards.

 

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Meghavi
Moderator
Moderator

Hi,

Slower I2C reads in Windows was due to delay introduced in library API implementation. Refer to this thread for more details - https://community.cypress.com/t5/USB-Low-Full-High-Speed/CY7C65211-USB-Serial-SDK-Long-delays-betwee... 

I2C Read API in library for Linux does not contain any such delays and should work without issues. Can you please test this at your end and let me know if you find similar delay in Linux?

Regards

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hankchu
New Contributor II

Dear  Meghavi:

 1) The S/W measurement for the time taken by Cypress API (USB-to-I2C)

 1-1) On Intel Denverton CPU + Linux OS :  It did the 1-byte I2C read/write.

 1-1-1)   CyOpen() takes 0.000054 second

 1-1-2)   CyI2CWrite() takes 0.007594 second.

 1-1-3)  CyI2CRead() takes 0.007998 second.

 1-1-4)  CyClose() takes 0.000023 second.

 

 1-2)  Are the time taken by Cyrpress API routines normal for CY7C65211 (USB-to-I2C)?

 

 

 2) Our customer asked us to enhance the performance of CY7C65211 (USB-to-I2C).

 2-1) And we are trying to port the Linux kernel driver for CY7C65211.

 

 2-2) Are there any concerns to port the CyOpen(), CyClose(), CyI2CRead() and CyI2CWrite() API routines to Linux kernel driver?

 

  Thank you.

Best Regards.

 

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hankchu
New Contributor II

Dear Meghavi:

    About the CY7C65211 (USB-to-I2C), the Linux kernel driver already worked on our product.

   And we are debuging/testing the functionalities and performance of the ported Linux kernel driver now.

    Have a nice day.

Best Regards.

 

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Meghavi
Moderator
Moderator

Hi

I am glad that the issue has been resolved. Can you please share what all changes have you done to reduce the delay? I would be helpful for other community members.

Please let me know if there are any other queries.

Regards

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hankchu
New Contributor II

Dear Meghavi:

   Thank you for your kind support.

   Please do us a favor to close this case.

Best Regards.

 

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