SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Configuring an EDMA channel to receive a single frame of data is useful, and is applicable to some systems. A majority of the time, however, data is going to be continuously transmitted and received throughout the entire operation of the processor. In this case, it is necessary to implement some form of linking such that the EDMA channels continuously reload the necessary parameter sets. In this example, McASP is configured to transmit and receive data on a T1 array. To simplify the example, only two channels are active for both transmit and receive data streams. Each channel receives packets of 128 elements. The packets are transferred from the serial port to internal memory and from internal memory to the serial port, as shown in Figure 16-43.
The McASP generates AREVT for every element received and generates AXEVT for every element transmitted. To service the data streams, them DMA channels associated with the McASP must be setup for 1D-to-1D transfers with A-synchronization.
Figure 16-44 shows the parameter entries for the channel for these transfers. To service the McASP continuously throughout DSP operation, the channels must be linked to a duplicate PaRAM set in the PaRAM. After all frames have been transferred, the EDMA channels reload and continue.
Figure 16-45 shows the reload parameters for the channel.