USB "segmented" transfer

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Hello Everybody,

 

If the data to be transfered to/from an USB enpoint is bigger than the endpoint size it has to be segmented and is transfered in several packets.

 

My question: Can more than 1 of this segmented transfers be active at the same time inside a device or do I just need to track a single transfer ?

 

TiA, Tommy

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Last Edited: Mon. Apr 1, 2019 - 01:36 PM
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For a given endpoint, no, there can only be 1 transfer in progress per endpont.

But yes if it involves different endpoints (you can of course have multiple endpoints).

 

(It's been a long time since I worked with USB so I wouldn't take this as gospel).

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It probably depends on the hardware.  With the Xmega AU, you can queue up a data buffer with a size up to 1023 bytes.  The hardware will send it in chunks equal to the low level data packet size.  That's probably 64 bytes for full speed.