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USB Communication

Naveed Ahmed

Hi,

i am new to USB communication. I am using LPC1768 and using USBCDC example to communicate. In this example it makes virtual com port over which we can send or receive data.

I am confused that com port maximum bandwidth can be known by its Baudrate that is 9600, etc etc.
The question is that can virtual com port in my case have bandwidth like USB over which we can send huge amount of data i.e files and other large data.
Please help me
Thanks in advance.

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    It is possible to use many different methods to transfer data over a USB cable.

    But a common implementation will use control transfers, which has a limit of max 64 bytes/transfer and one transfer per millisecond. So a maximum transfer rate of 64000 bytes/second. With 8 bits/byte, the maximum transfer rate excluding handling of handshake etc would then be 512000 baud.

    With own drivers that makes use of other transfer modes, you can get higher transfer rates.
    The following is an example of such an implementation:
    www.pjrc.com/.../usb_serial.html
    As you can see, the benchmark indicates transfer sepeds of 1MB/s - or about 8Mbaud. A decent result from a 12Mbit/s USB link.

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  • 0

    It is possible to use many different methods to transfer data over a USB cable.

    But a common implementation will use control transfers, which has a limit of max 64 bytes/transfer and one transfer per millisecond. So a maximum transfer rate of 64000 bytes/second. With 8 bits/byte, the maximum transfer rate excluding handling of handshake etc would then be 512000 baud.

    With own drivers that makes use of other transfer modes, you can get higher transfer rates.
    The following is an example of such an implementation:
    www.pjrc.com/.../usb_serial.html
    As you can see, the benchmark indicates transfer sepeds of 1MB/s - or about 8Mbaud. A decent result from a 12Mbit/s USB link.

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