Initialization/Application Information - Freescale Semiconductor MCF52277 Reference Manual

Enhanced Direct Memory Access (eDMA)
eDMA
eDMA Engine
Read Data
Write Data
Address
17.8

Initialization/Application Information

17.8.1 eDMA Initialization
A typical initialization of the eDMA has the following sequence:
1. Write the EDMA_CR if a configuration other than the default is desired.
2. Write the channel priority levels into the DCHPRIn registers if a configuration other than the
default is desired.
3. Enable error interrupts in the EDMA_EEI if so desired.
4. Write the 32-byte TCD for each channel that may request service.
5. Enable any hardware service requests via the EDMA_ERQ.
6. Request channel service by software (setting the TCDn_CSR[START] bit) or hardware (slave
device asserting its eDMA peripheral request signal).
17-28
Data Path
Figure 17-31. eDMA Operation, Part 3
MCF52277 Reference Manual, Rev. 1
Transfer
Control
Descriptor (TCD)
64
Program Model/
Channel Arbitration
Address Path
Control
eDMA Peripheral
Request
Write Address
Write Data
0
1
2
n-1
Read Data
eDMA Done
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