How to Initiate the data transfer from USB Device in KL25Z...?

[charanreddy]

Hi ,

     After connecting the USB device to the Host, initially Host will ask for the different data from the device. After this initialization is completed again if the device wants to initiate the transfer what need to be done on the device application.

Regards,

Charan

[mjbcswitzerland · Accepted solution]

Hi

USB device doesn't initiate transmissions, it prepares data in its output buffers so that the host's IN polling tokens cause then to be transferred.

Regards

Mark

Kinetis: http://www.utasker.com/kinetis.html

USB User's Guide: http://www.utasker.com/docs/uTasker/USB_User_Guide.PDF

Composite USB: http://www.utasker.com/kinetis/USB_Device.html

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[charanreddy]

Hi Mark,

          Thank you very much for your replay and also the references which are very useful. Is there any method (other than reinserting the Device) that i can do in my host so that the data in USB Device will automatically updated in the files.

Regards,

Charan

[mjbcswitzerland]

Charan

I don't know whether I have understood the question - you may need to explain in more detail what the problem is and what you need to do.

Possibly you are developing a USB device that is acting as mass storage device and you have changed data on the disk and need to cause the host to update it (since it will cache the file system and not know of changes). If this is the case I don't think that there is any method other than to disconnect the device and re-attach again so that the host re-enumerates and re-synchronises to the file system. Generally I would avoid modifying data on the disk when it is 'inserted' at the host since the host may write something (not knowing that the FAT has been modifed at the device) which could even lead to disk corruption/loss of data - the host doesn't expect data to change!

Regards

Mark

[charanreddy]

Hi Mark,

             I need the same thing which you are explaining. Actually i need to display the graph of the real time data from the device. So, if there is any method which can update the data on device so that the graph will be automatically Updated or else Is there any method by which host can can send periodic IN tokens for the device so that the data gets updated.

Regards

Charan