9.2.21 UDPHS DMA Channel Transfer Descriptor

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:
  • The address must be aligned: 0xXXXX0
  • Next Descriptor Address Register: UDPHS_DMANXTDSCx
• Offset 4:
  • The address must be aligned: 0xXXXX4
  • DMA Channelx Address Register: UDPHS_DMAADDRESSx
• Offset 8:
  • The address must be aligned: 0xXXXX8
  • DMA Channelx Control Register: UDPHS_DMACONTROLx

To use the DMA channel transfer descriptor, fill the structures with the correct value (as described in the following pages). Then write directly in UDPHS_DMANXTDSCx the address of the descriptor to be used first. Then write '1' in the LDNXT_DSC bit of UDPHS_DMACONTROLx (load next channel transfer descriptor). The descriptor is automatically loaded upon Endpointx request for packet transfer.