MSC8113 Reference Manual, Rev. 0
16-30
Freescale Semiconductor
Direct Memory Access (DMA) Controller
16.3.1 DMA Priority Type
The DMA controller supports both fixed-priority and round-robin algorithms. The DPCRx[AM]
bit controls the priority scheme mode of the DMA controller:
When cleared (RESET value), the bit selects Fixed-Priority priority mode (MSC8102
mode). The DCHCRx[PRIO] bits are active
When set, the bit selects Round-Robin mode. The DCHCRx[PRIO] bit must be cleared
(all bits = 0). Failure to clear these bits causes unpredictable behavior.
Writing to DCPR[AM] to change the priority mode is permitted only when all DMA channels are
inactive.
16.3.1.1 Fixed-Priority Mode
In Fixed-Priority mode, every channel has a priority set by the user in the DCHCRx[PRIO]
register. This priority is not changed by the DMA. If two channels have the same priority, the
channel with the lower channel number has the higher priority. Figure 16-23 illustrates the fixed
priority flow.
16.3.1.2 Round-Robin Priority Mode
The round-robin algorithm can be described as two analog clocks. One clock is for the channels
associated with the system bus, and the other clock is for the channels associated with the local
bus. Each clock has sixteen markers, one for each of the 16 channels, and one big hand, which
rotates from 0 to 15 clockwise. Figure 16-24 illustrates the system and local bus round robin
clocks. The pointer hand indicates the current active channel (the markers on the clock) used by
the local bus and the system bus. When the transfer is complete for a selected channel, the clock
hand moves on to the next channel.
Figure 16-23. Fixed-Priority Flow Diagram
Serve This Channel
Find Channel With
Highest Requesting Priority
RESET
Summary of Contents for MSC8113
Page 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
Page 20: ...MSC8113 Reference Manual Rev 0 xx Freescale Semiconductor Contents ...
Page 28: ...MSC8113 Reference Manual Rev 0 xxviii Freescale Semiconductor ...
Page 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Page 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Page 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Page 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Page 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Page 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Page 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Page 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Page 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Page 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Page 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Page 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Page 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Page 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Page 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Page 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Page 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...