at32uc3b0512-z2ues ATMEL Corporation, at32uc3b0512-z2ues Datasheet - Page 402

• Manufacturer Part Number: at32uc3b0512-z2ues
• Description: 32-bit Avr Microcontroller
• Manufacturer: ATMEL Corporation

22.7.4.2
22.7.4.3
32059J–12/2010
USB DMA Channel X Registers
(Current Transfer Descriptor)
Next Descriptor Address
Memory Area
Data Buffer 1
Data Buffer 2
Data Buffer 3
HSB Address
Control
Status
DMA Channel descriptor
Programming a chanel:
Figure 22-30. Example of DMA Chained List
The DMA channel transfer descriptor is loaded from the memory.
Be careful with the alignment of this buffer.
The structure of the DMA channel transfer descriptor is defined by three parameters as
described below:
• Offset 0:
• Offset 4:
• Offset 8:
Each DMA transfer is unidirectionnal. Direction depends on the type of the associated endpoint
(IN or OUT).
Three registers, the UDDMAnNEXTDESC, the UDDMAnADDR and UDDMAnCONTROL need
to be programmed to set up wether single or multiple transfer is used.
The following example refers to OUT endpoint. For IN endpoint, the programming is symmetric.
– The address must be aligned: 0xXXXX0
– DMA Channel n Next Descriptor Address Register: DMAnNXTDESCADDR
– The address must be aligned: 0xXXXX4
– DMA Channel n HSB Address Register: DMAnADDR
– The address must be aligned: 0xXXXX8
– DMA Channel n Control Register: DMAnCONTROL
Next Descriptor Address
Transfer Descriptor
HSB Address
Control
Next Descriptor Address
Transfer Descriptor
HSB Address
Control
Next Descriptor Address
Transfer Descriptor
HSB Address
Control
AT32UC3B
NULL
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