MSC8144E Reference Manual, Rev. 3
14-4
Freescale
Semiconductor
Direct Memory Access (DMA) Controller
14.2.2 One-Dimensional Cyclic Buffer
A cyclic buffer is a continuous buffer. When the buffer current address reaches zero, the pointer
jumps back to the base address and the buffer executes again. Figure 14-3 shows an example of a
cyclic buffer.
Figure 14-3. One-Dimensional Cyclic Buffer
Table 14-2 lists the channel parameters values for channel BD8 when a 0x200 byte block is read
from address 0x1000. An interrupt is generated when the buffer size reaches zero, and the
transfer restarts from the base address 0x1000.
Table 14-2. Channel Parameter Values for a Cyclic Buffer
BD
BD Parameters
Value
Description
8
BD_ADDR
0x1000
External memory buffer current address.
BD_SIZE
0x200
Size of transfer left for this buffer.
BD_BSIZE
0x200
Buffer base size of cyclic buffer.
BD_ATTR
SST
0x1
Generate interrupt when buffer ends.
CONT
0x1
Continuous mode: the buffer is not closed when the size
reaches zero.
CYC
0x1
Reinitialize BD_ADDR to original value when the size reaches
zero.
BTSZ
0x7
Maximum transfer size is one burst of 64 bytes.
0x1000
0x11F8
Interrupt
BD8
Summary of Contents for MSC8144E
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Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...