Motorola MSC8101 ADS User's Guide Page 111

  • Download
  • Add to my manuals
  • Print
  • Page
    / 346
  • Table of contents
  • BOOKMARKS
  • Rated. / 5. Based on customer reviews
Page view 110
DMA Programming Basics
DMA Channels 6-3
Figure 6-2. Normal Mode Example
6.1.1.2 Flyby Mode (Single Access)
Flyby mode does not require two DMA channels to complete a data transfer between a
peripheral and a memory module. In this mode, the transaction occurs between two
resources with the same port size
1
on the same bus so that it can be executed by a single
channel without going through the DMA FIFO. The read cycle data is transferred directly
“on the fly” to its destination.
There are constraints on which DMA channels can be used during a flyby transaction. If
the transaction is a read transaction from memory, then an even-numbered DMA channel
must be programmed for the transfer. If a write transaction to memory is required, an
odd-numbered DMA channel must be programmed. The channel must be programmed to
external request mode by clearing the (DCHCRx[25]:INT) bit, and the corresponding
BD_ADDR field is programmed to the memory address. The DCHCR requestor number
field points to the peripheral.
6.1.2 Transfer Types
Each DMA channel is configured in one of six possible ways. This section describes each
configuration.
1. Port size is programmed in the BRx registers. It can be 8, 16, 32, or 64 bits.
MEMC
DMA
Controller
SIU
Host I/F
16-bit
PowerPC bus
64/32-bit
PowerPC Local
PowerPC System 64-bit
HDI16
EFCOP
512 KB
SRAM
64-bit
MEMC
1) Read from source, write to DMA FIFO
2) Read from DMA FIFO, write to Destination
DMA Transfer Steps, Normal Mode
Page view 110
1 2 ... 106 107 108 109 110 111 112 113 114 115 116 ... 345 346

Comments to this Manuals

No comments