Intel® PXA255 Processor Developer’s Manual
5-1
DMA Controller
5
This chapter describes the on-chip DMA controller (DMAC) for the PXA255 processor. The
DMAC transfers data to and from main memory in response to requests generated by internal and
external peripherals. The peripherals do not directly supply addresses and commands to the
memory system. The DMAC has 16 DMA channels, 0 through 15, and every DMA request from
the peripheral generates at least one memory bus cycle.
5.1
DMA Description
The DMAC supports only flow-through transfers.
Flow-through data passes through the DMAC before the data is latched by the destination in its
buffers/memory. This DMAC can perform memory-to-memory moves with flow-through transfers.
Figure 5-1
provides an overview of the DMAC.
Table 5-1
provides a list of the DMAC signals and
descriptions.
Figure 5-1. DMAC Block Diagram
DDADR0
DSADR0
DTADR0
DCMD0
Channel 0
Channel 15
16 DMA Channels
DRCMR0
Control Registers
System Bus (internal)
Peripheral Bus
DREQ[1:0]
PREQ[37:0]
DMA_IRQ
DMA Controller
DINT
DCSR0
(external)
(internal)
(internal)
(internal)
Memory Controller
Summary of Contents for PXA255
Page 1: ...Intel PXA255 Processor Developer s Manual January 2004 Order Number 278693 002 ...
Page 24: ...xxiv Intel PXA255 Processor Developer s Manual Contents ...
Page 30: ...1 6 Intel PXA255 Processor Developer s Manual Introduction ...
Page 310: ...7 46 Intel PXA255 Processor Developer s Manual LCD Controller ...
Page 330: ...8 20 Intel PXA255 Processor Developer s Manual Synchronous Serial Port Controller ...
Page 358: ...9 28 Intel PXA255 Processor Developer s Manual I2 C Bus Interface Unit ...
Page 488: ...13 36 Intel PXA255 Processor Developer s Manual AC 97 Controller Unit ...
Page 572: ...16 30 Intel PXA255 Processor Developer s Manual Network SSP Serial Port ...
Page 599: ...Intel PXA255 Processor Developer s Manual 17 27 Hardware UART ...
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