SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
In order to set up data transfers from the VPDMA, a data transfer descriptor is added into a list. The fields used for an Inbound and Outbound descriptor vary slightly. An outbound transfer can have two different outbound transfers. The two transfers are the main data transfer and a write of an Inbound Descriptor. The created inbound descriptor is formatted so it can be read back in directly to the next channel specified in the original descriptor.
Figure 12-49 Inbound Data Transfer Descriptor Format
Figure 12-50 Outbound Data Transfer Descriptor FormatThe general data transfer Descriptor formats can be seen in the above figures. The descriptor consists of 8 × 32bit words. A Data Transfer Descriptor will be removed from the list when the resource specified by the Channel field is free. If the Channel is not free when the list reaches a data transfer descriptor then the list will stall until the current transfer on the channel has completed.