UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
179 of 362
NXP Semiconductors
UM10208
Chapter 15: LPC2800 GPDMA
3.1.5 DMA request priority
DMA channel priority rotates. The GPDMA central logic continually scans the eight
channels and associated flow control signals, for channels that are ready to transfer data.
This means that each channel has equal opportunity to transfer data, and helps prevent
memory-to-memory transfers from “starving” access by other channels.
3.1.6 Interrupt generation
A combined interrupt output is generated as the logical OR of the individual interrupt
requests of the GPDMA, and is connected to the LPC288x interrupt controller.
3.2 GPDMA system connections
The connection of the GPDMA channels to the supported peripheral devices has two
aspects:
1. The address of the source or destination register in the peripheral must be
programmed into the channel’s Source or Destination Address Register
2. The channel’s Configuration register must be programmed to respond to the
peripheral’s request signal.
shows the values to be programmed into the Configuration register for each
of the supported peripherals.
The final two entries in the table above represent external requests for DMA transfer. If
only one such request is needed, connecting it to A19 will help maximize the external
memory address space. To use one or both of these pads for this purpose, the pad(s)
must be programmed as GP input in the I/O Configuration module. This is described in
Table 194. DMA connections
Peripheral function
Value in ID fields in the Channel
Configuration Register
Ultimate source or
destination
SD/MMC Single
1
SD/MMC Burst
2
UART Rx
3
Remote Async Tx
UART Tx
4
Remote Async Rx
I
2
C
5
SAO1 A channel
6
I2S out
SAO1 B channel
7
I2S out
SAO2 A channel
8
dual DAC A
SAO2 B channel
9
dual DAC B
SAI1 A channel
10
I
2
S in
SAI1 B channel
11
I
2
S in
SAI4 A channel
16
dual ADC A
SAI4 B channel
17
dual ADC B
LCD output
18
MPMC_A19
19
MPMC_A17
20