UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
177 of 362
1.
Introduction
The General Purpose DMA Controller (GPDMA) is an AMBA AHB compliant master that
provides DMA support to selected LPC288x peripherals. Peripherals that can be serviced
by the GPDMA channels include the MCI/SD card interface, UART Tx and/or Rx, the I
2
C
interface, the Streaming Analog Out (SAO) front-ends to the I
2
S/DAO and 16-bit dual
DACs, the Streaming Analog In (SAI) interfaces for data from the I
2
S/DAI and 16-bit dual
ADCs, and output to the LCD interface.
2.
Features of the GPDMA
•
Eight DMA channels. Each channel can support a unidirectional transfer, or a pair of
channels can be used together to follow a linked list of buffer addresses and transfer
counts.
The GPDMA provides 16 peripheral DMA request lines. Most of these are connected
to the peripherals listed above; two can be used for external requests.
•
The GPDMA supports a subset of the flow control signals supported by ARM DMA
channels, specifically “single” but not “burst” operation.
•
Memory-to-memory, memory-to-peripheral, peripheral-to-memory, and
peripheral-to-peripheral transfers.
•
Scatter or gather DMA is supported through the use of linked lists. This means that
successive source or destination areas do not have to occupy contiguous areas of
memory.
•
Rotating channel priority. Each DMA channel has equal opportunity to perform
transfers.
•
The GPDMA is one of three AHB masters in the LPC288x, the others being the ARM7
processor and the USB interface.
•
Incrementing or non-incrementing addressing for source and destination.
•
Supports 8, 16, and 32 bit wide transactions.
•
GPDMA channels can be programmed to swap data between big- and little-endian
formats during a transfer.
•
An interrupt to the processor can be generated on DMA completion, when a DMA
channel is halfway to completion, or when a DMA error has occurred.
3.
Functional overview
This chapter describes the major functional blocks of the GPDMA. It contains the following
sections:
•
GPDMA functional description
•
DMA system connections
UM10208
Chapter 15: General Purpose DMA controller (GPDMA)
Rev. 02 — 1 June 2007
User manual