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Architecture
623
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Enhanced Direct Memory Access (EDMA3) Controller
17.2.18 Emulation Considerations
During debug when using the emulator, the CPU(s) may be halted on an execute packet boundary for
single-stepping, benchmarking, profiling, or other debug purposes. During an emulation halt, the EDMA3
channel controller and transfer controller operations continue. Events continue to be latched and
processed and transfer requests continue to be submitted and serviced.
Since EDMA3 is involved in servicing multiple master and slave peripherals, it is not feasible to have an
independent behavior of the EDMA3 for emulation halts. EDMA3 functionality would be coupled with the
peripherals it is servicing, which might have different behavior during emulation halts. For example, if a
multichannel buffered serial port (McBSP) is halted during an emulation access (FREE = 0 and SOFT = 0
or 1 in the McBSP registers), the McBSP stops generating the McBSP receive or transmit events (REVT
or XEVT) to the EDMA. From the point of view of the McBSP, the EDMA3 is suspended, but other
peripherals (for example, a timer) still assert events and will be serviced by the EDMA.
17.3 Transfer Examples
The EDMA3 channel controller performs a variety of transfers depending on the parameter configuration.
The following sections provides a description and PaRAM configuration for some typical use case
scenarios.
17.3.1 Block Move Example
The most basic transfer performed by the EDMA3 is a block move. During device operation it is often
necessary to transfer a block of data from one location to another, usually between on-chip and off-chip
memory.
In this example, a section of data is to be copied from external memory to internal L2 SRAM. A data block
of 256 bytes residing at address 4000 0000h (external memory ) needs to be transferred to internal
address 1180 0000h (L2), as shown in
shows the parameters for this transfer.
The source address for the transfer is set to the start of the data block in external memory, and the
destination address is set to the start of the data block in L2. If the data block is less than 64K bytes, the
PaRAM configuration in
holds true with the synchronization type set to A-synchronized and
indexes cleared to 0. If the amount of data is greater than 64K bytes, BCNT and the B-indexes need to be
set appropriately with the synchronization type set to AB-synchronized. The STATIC bit in OPT is set to
prevent linking.
This transfer example may also be set up using QDMA. For successive transfer submissions, of a similar
nature, the number of cycles used to submit the transfer are fewer depending on the number of changing
transfer parameters. You may program the QDMA trigger word to be the highest numbered offset in the
PaRAM set that undergoes change.
Figure 17-15. Block Move Example