[usb] dma

[meizhangxiong <meizx@ict.ac.cn>]

hi,all
I have there questions about Mr. Rudolf Usselmann's usb device core.
1,In the document,USB Function IP Core 3.1.1,the usb core surports a double buffering feature,and data is being retrieved/filled from/to the buffers in a round robin fation. In this document 3.2,however,in DMA mode,only one buffer(buffer 0)is used,buffer 1 is never used in DMA mode.I want to know if there is any conflition between these two representations and why.
2,In the interupt servcie routine,how do the buffer0/buffer1 exchange data with usb funtion controller?By DMA mode?
3,In usbf_pe.v,the following sentence,
// New Size (to be written to register file)
always @(posedge clk)
	new_sizeb <= #1 (out_op & dma_en) ? max_pl_sz : (in_op ? size_next : sizu_c);
Does it mean that usb core use max_pl_sz space for each output transaction?

Regards
				
　　　　　　　　　　　　　　meizhangxiong
　　　　　　　　　　　　　　meizx@ict.ac.cn
　　　　　　　　　　　　　　　　　2002-07-24
--
To unsubscribe from usb mailing list please visit http://www.opencores.org/mailinglists.shtml