NXP Semiconductors LPC43 Series User Manual

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NXP Semiconductors LPC43 Series User Manual Manual pdf 558 page image

UM10503 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.User manual Rev. 1.3 — 6 July 2012 558 of 1269NXP Semiconductors UM10503Chapter 23: LPC43xx USB0 Host/Device/OTG controllerAfter an endpoint is readied, the dTD will be copied into this queue head overlay area bythe device controller. Until a transfer is expired, software must not write the queue headoverlay area or the associated transfer descriptor. When the transfer is complete, thedevice controller will write the results back to the original transfer descriptor and advancethe queue. See dTD for a description of the overlay fields.23.9.1.4 Set-up buffer descriptor fieldsThe set-up buffer is dedicated storage for the 8-byte data that follows a set-up PID.Remark: Each endpoint has a TX and an RX dQH associated with it, and only the RXqueue head is used for receiving setup data packets.23.9.2 Endpoint transfer descriptor (dTD)The dTD describes to the device controller the location and quantity of data to besent/received for a given transfer. The DCD should not attempt to modify any field in anactive dTD except the Next Link Pointer, which should only be modified as described inSection 23.10.11.Table 436. Set-up bufferDword Access Bit Name Description1 R/W 31:0 BUF0 Setup buffer 0This buffer contains bytes 3 to 0 of an incoming setupbuffer packet and is written by the device controller tobe read by software.2 R/W 31:0 BUF1 Setup buffer 1This buffer contains bytes 7 to 4 of an incoming setupbuffer packet and is written by the device controller tobe read by software.Table 437. Next dTD pointerAccess Bit Name DescriptionRO 31:5 Next_link_pointer Next link pointerThis field contains the physical memory address of the nextdTD to be processed. The field corresponds to memoryaddress signals [31:5], respectively.4:1 - reserved0 T TerminateThis bit indicates to the device controller when there are nomore valid entries in the queue.1 - pointer is invalid0 - Pointer is valid, i.e. pointer points to a valid transferelement descriptor.