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    USB device( related to DMA and sram) and USB protocol

    USB device have SRAM and DMA sub-modules:

    1. what is the role of SRAM in USB device??
    2. a. how DMA controller knows to initiate a request to memory(either read or write)??
    b. how Endpoint get data from buffers and how Endpoint write data into the buffer??
    c. who will call the DMA controller for initiating request to Memory device??

    please give clarity on above listed queries.

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    Re: USB device( related to DMA and sram) and USB protocol

    Non of the question can be answered without referring to the specific USB device type und functionality. Which device are asking about?



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    Re: USB device( related to DMA and sram) and USB protocol

    USB Mass storage like 32 GB pen drive
    Last edited by FvM; 3rd April 2020 at 22:27. Reason: Merged with previous closely related thread



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    USB protocol related queries

    1. a. What sequences steps will go internally between hub and host.
    b. What are the disadvantages for the device if suddenly unplug the device while transferring the data??

    Ex:Suppose 1 GB data transferring from host to USB device (mass storage device) or vice versa, All of suddenly pen-drive or USB device is removed before complete the transfer of data.

    2. a. How USB core handles various error conditions??
    b. Explain various steps that goes into interrupt handling??



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    Re: USB protocol related queries

    The standard caution usually appears in the instructions: 'To avoid loss of data do not turn off device or disconnect it.'

    The receiving device needs to know where the final byte and final sector is, so it can close the file and list its place in the file allocation table.

    The sending device has a protocol of checking that data can be sent, and that each byte was received free of errors. If it stops getting an answer back, it either generates an error or it freezes.



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    Re: USB protocol related queries

    A mass storage device is operated with read and write to logical blocks, the file management is performed by the controlling computer. Interrupting a transaction in the middle involves a high risk of corrupting the file system. Fault tolerant file systems have special capabilities to recover from such events, but they aren't present in the mostly used Windows PC file systems NTFS and FAT.



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    Re: USB protocol related queries

    I am expecting answers in the form of USB verification (ASIC Design Verification).
    I am not able to recognize the answer in the form of USB Verification, please answer in the form of USB Design Verification for the above queries.



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    Re: USB protocol related queries

    I don't see a relation of your previous questions to ASIC design, it's neither mentioned nor obvious in any regard. The discussed problems, although a bit vague, are general USB topics. The perspective won't change if they occur in the ASIC implementation of an USB controller.

    Please clarify.



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  9. #9
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    Re: USB protocol related queries

    Don't know how to reply for this. What you answered is ok at high level.
    I am working in VlSI (Design Verification) what you mention technical terms I am not heard or didn't seen at project specification.

    I will ask Admin, Admin please move this thread to ASIC or FPGA group, its better to get related answers further to me.



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    Re: USB protocol related queries

    I would immediately move the thread to ASIC section - if it had any ASIC related questions. But yet there are none. Please review your questions.



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