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USB isochronous transfer queries

Question asked by Binaek Sarkar on Apr 6, 2015
Latest reply on Apr 9, 2015 by CarlosCasillas



I have some queries regarding usb isochronous endpoint operation for device controller. I am referring to the document "IMX6DQRM-Rev1.pdf" section 65.4.5.


1. During an isochronous in transfer, does Dqh contain only one Dtd which has only one  Iso (micro)frame or does Dqh contain one or multiple linked Dtds which has an input buffer filled with many iso frame/microframe? If multiple then how does device controller identify (micro)frame boundaries in dtds?


2. Is there any DMA operation involved while moving data between DTD and TX/RX FIFO? If DMA is present then what is the DMA restriction of buffer size and start address alignment?