SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Non-bursting peripherals include the on-chip multichannel audio serial port (McASP) and many external devices, such as codecs. Regardless of the peripheral, the EDMA channel configuration is the same.
The McASP transmit and receive data streams are treated independently by the EDMA. The transmit and receive data streams can have completely different counts, data sizes, and formats.
To transfer the incoming data stream to its proper location in DDR memory, the EDMA channel must be set up for a 1D-to-1D transfer with A-synchronization. Because an event (AREVT) is generated for every word as it arrives, it is necessary to have the EDMA issue the transfer request for each element individually. Figure 18-40 shows the parameters for this transfer. The source address of the EDMA channel is set to the data port address (DAT) for McASP, and the destination address is set to the start of the data block in DDR. Because the address of serializer buffer is fixed, the source B index is cleared to 0 (no modification) and the destination B index is set to 0x2 (increment).
Based on the premise that serial data is typically a high priority, the EDMA channel should be programmed to be on queue 0.
Figure 18-39 shows servicing incoming McASP data.
(a) EDMA Parameters |
Parameter Contents | Parameter | |||||
0010 0000h | Channel Options Parameter (OPT) | |||||
McASP RX Address | Channel Source Address (SRC) | |||||
0100h | 0001h | Count for 2nd Dimension (BCNT) | Count for 1st Dimension (ACNT) | |||
Channel Destination Address (DST) | Channel Destination Address (DST) | |||||
0001h | 0000h | Destination BCNT Index (DBIDX) | Source BCNT Index (SBIDX) | |||
0000h | FFFFh | BCNT Reload (BCNTRLD) | Link Address (LINK) | |||
0000h | 0000h | Destination CCNT Index (DCIDX) | Source CCNT Index (SCIDX) | |||
0000h | 0004h | Reserved | Count for 3rd Dimension (CCNT) |
(b) Channel Options Parameter (OPT) Content