Texas Instruments C2000 Workshop Guide And Lab Manual

Direct Memory Access (DMA)
9 - 8 C2000 Microcontroller Workshop - Direct Memory Access Controller
DMA configured to re-init after transfer (CONTINUOUS = 1)
Ping-Pong Example Register Setup
SRC_BURST_STEP
SRC_TRANSFER_STEP
0x0000
DST_BURST_STEP
DST_TRANSFER_STEP
0x0001
SRC_ADDR_SHADOW
DST_ADDR_SHADOW
BURST_SIZE*
TRANSFER_SIZE*
0x0000
1 word/burst
0x0031
50 bursts/transfer
* Size registers are N-1
Objective: Buffer ADC ch. 0 ping-pong style, 50 samples per buffer
don’t care
since BURST_SIZE = 0
don’t care
since BURST_SIZE = 0
0x00000B00
starting address
0x0000C140
starting address**
Read/Write Data
Add Burst Step
to Address
Pointer
End Transfer
Add Transfer Step
to Address Pointer
Moved
“Burst Size”
Words?
Moved
“Transfer Size”
Bursts?
Y
Y
N
N
Wait for event to
start/continue transfer
Start Transfer
Convert ADC Channel ADCINA0 – 1 conversion per trigger (i.e. ePWM2SOCA)
DMA Registers:
ADC Registers:
Other:
** DST_ADDR_SHADOW must be changed between ping and pong buffer address in
the DMA ISR. Typically use a relocatable symbol in your code, not a hard value.
DMA Priority Modes
Channel Priority Modes
 Round Robin Mode:
 All channels have equal priority
 After each enabled channel has
transferred a burst of words, the
next enabled channel is serviced
in round robin fashion
 Channel 1 High Priority Mode:
 Same as Round Robin except CH1
can interrupt DMA state machine
 If CH1 trigger occurs, the current
word (not the complete burst) on
any other channel is completed
and execution is halted
 CH1 is serviced for complete burst
 When completed, execution
returns to previous active channel
 This mode is intended primarily
for the ADC, but can be used by
any DMA event configured to
trigger CH1
DMA
event?
CH6 CH1
CH2CH5
CH4 CH3
Y
N

Texas Instruments C2000 Specifications

General

Brand	Texas Instruments
Model	C2000
Category	Microcontrollers
Language	English