Appendix A
11.5.3 Setting Up a Transfer
The following list provides a quick guide for the typical steps involved in setting up a transfer.
Step 1.
Initiating a DMA/QDMA channel
(a) Determine the type of channel (QDMA or DMA) to be used.
(b) Channel mapping
(i) If using a QDMA channel, program the QCHMAP with the parameter set number to
which the channel maps and the trigger word.
(ii) If using a DMA channel, program the DCHMAP with the parameter set number to
which the channel maps.
(c) If the channel is being used in the context of a shadow region, ensure the DRAE/DRAEH
for the region is properly set up to allow read write accesses to bits in the event registers
and interrupt registers in the Shadow region memory map. The subsequent steps in this
process should be done using the respective shadow region registers. (Shadow region
descriptions and usage are provided in
(d) Determine the type of triggering used.
(i) If external events are used for triggering (DMA channels), enable the respective event
in EER/EERH by writing into EESR/EESRH.
(ii) If QDMA Channel is used, enable the channel in QEER by writing into QEESR.
(e) Queue setup
(i) If a QDMA channel is used, set up the QDMAQNUM to map the channel to the
respective event queue.
(ii) If a DMA channel is used, set up the DMAQNUM to map the event to the respective
event queue.
Step 2.
Parameter set setup
(a) Program the PaRAM set number associated with the channel. Note that if it is a QDMA
channel, the PaRAM entry that is configured as trigger word is written to last.
Alternatively, enable the QDMA channel (step 1-b-ii above) just before the write to the
trigger word.
See
for parameter set field setups for different types of transfers. See the
sections on chaining (
) and interrupt completion (
) on how to
set up final/intermediate completion chaining and/or interrupts.
Step 3.
Interrupt setup
(a) Enable the interrupt in the IER/IERH by writing into IESR/IESRH.
(b) Ensure that the EDMA3CC completion interrupt (either the global or the shadow region
interrupt) is enabled properly in the device interrupt controller.
(c) Ensure the EDMA3CC completion interrupt (this refers to either the Global interrupt or the
shadow region interrupt) is enabled properly in the Device Interrupt controller.
(d) Set up the interrupt controller properly to receive the expected EDMA3 interrupt.
1020
Enhanced Direct Memory Access (EDMA)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated