Enhanced Direct Memory Access (eDMA)
MPC5565 Microcontroller Reference Manual, Rev. 1.0
9-42
Freescale Semiconductor
c) read_byte (0x1004), read_byte(0x1005), read_byte(0x1006), read_byte(0x1007)
d) write_word (0x2004) -> second iteration of the minor loop
e) read_byte (0x1008), read_byte(0x1009), read_byte(0x100a), read_byte(0x100b)
f) write_word (0x2008) -> third iteration of the minor loop
g) read_byte (0x100c), read_byte(0x100d), read_byte(0x100e), read_byte(0x100f)
h) write_word (0x200c) -> last iteration of the minor loop -> major loop complete
6. eDMA engine writes: TCD.SADDR = 0x1000, TCD.DADDR = 0x2000,
TCD.CITER = 1 (TCD.BITER).
7. eDMA engine writes: TCD.ACTIVE = 0, TCD.DONE = 1, EDMA_IRQR
n
= 1.
8. The channel retires.
The eDMA goes idle or services the next channel.
9.4.5.2
Multiple Requests
The next example is the same as previous with the exception of transferring 32 bytes via two hardware
requests. The only fields that change are the major loop iteration count and the final address offsets. The
eDMA is programmed for two iterations of the major loop transferring 16 bytes per iteration. After the
channel’s hardware requests are enabled in the EDMA_ERQR, channel service requests are initiated by
the slave device (set ERQR after TCD; TCD.START = 0).
TCD.CITER = TCD.BITER = 2
TCD.NBYTES = 16
TCD.SADDR = 0x1000
TCD.SOFF = 1
TCD.SSIZE = 0
TCD.SLAST = –32
TCD.DADDR = 0x2000
TCD.DOFF = 4
TCD.DSIZE = 2
TCD.DLAST_SGA= –32
TCD.INT_MAJ = 1
TCD.START = 0 (Initialize all other fields before writing this bit.)
All other TCD fields = 0
This generates the following sequence of events:
1. First hardware (eDMA peripheral request) request for channel service.
2. The channel is selected by arbitration for servicing.
3. eDMA engine writes: TCD.DONE = 0, TCD.START = 0, TCD.ACTIVE = 1.
4. eDMA engine reads: channel TCD data from local memory to internal register file.
Summary of Contents for MPC5565
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Page 34: ...MPC5565 Reference Manual Rev 1 0 Freescale Semiconductor 15...
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Page 553: ...Flash Memory MPC5565 Microcontroller Reference Manual Rev 1 0 13 38 Freescale Semiconductor...
Page 559: ...SRAM MPC5565 Microcontroller Reference Manual Rev 1 0 14 6 Freescale Semiconductor...
Page 973: ...Preface MPC5565 Microcontroller Reference Manual Rev 1 0 21 36 Freescale Semiconductor...
Page 1153: ...Calibration MPC5565 Microcontroller Reference Manual Rev 1 0 B 8 Freescale Semiconductor...