UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
184 of 362
NXP Semiconductors
UM10208
Chapter 15: LPC2800 GPDMA
4.2.5 Channel Enable Registers (DMA[0..7]Enab - 0x8010 3810..38F0)
4.2.6 Transfer Count Registers (DMA[0..7]Count - 0x8010 381C..38FC)
4.2.7 Alternate Source Address Registers (DMA[0..7]AltSource -
0x8010 3A00..3A70)
4.2.8 Alternate Destination Address Registers (DMA[0..7]AltDest -
0x8010 3A04..3A74)
Table 201. Channel Enable Registers (DMA[0..7]Enab - 0x8010 3810..38F0)
Bit
Symbol Description
Reset
Value
0
Writing a 1 to this bit enables a channel, and writing a 0 to this bit
disables it. Reading this register returns whether the channel is enabled.
0
31:1
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 202. Transfer Count Registers (DMA[0..7]Count - 0x8010 381C..38FC)
Bit
Symbol Description
Reset
Value
11:0
A DMA channel increments this value by 1 for each read/ write cycle, sets
its “half complete” bit in the DMA_IRQStat Register when bits 10:0 of this
register match bits 11:1 of its Transfer Length Register, and sets the its
“complete” bit in DMA_IRQStat and clears this register, when bits 11:0 of
this register match bits 11:0 of its Transfer Length Register.
Reading this register, while a transfer is in progress, returns the current
count value.
Write any value to this register to clear it to 0. Software/ firmware needs
to do this if it disabled a channel while a buffer was in progress, or if a
source peripheral terminated a buffer prematurely by asserting its
LSREQ handshaking signal.
0
31:12 -
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 203. Alternate Source Address Registers (DMA[0..7]AltSource - 0x8010 3A00..3A70)
Bit
Symbol Description
Reset
Value
31:0
This write-only register can be used to set a channel’s source address,
just like the main Source Address Register. When two channels are used
to follow a linked list of buffer addresses and counts in memory, the main
Destination Address of the “list-handling channel” should be set to the
address of the Alternate Source register in the “block-handling channel”.
(See “Scatter/Gather” on page 190).
NA
Table 204. Alternate Destination Address Registers (DMA[0..7]AltDest - 0x8010 3A04..3A74)
Bit
Symbol Description
Reset
Value
31:0
This write-only register can be used to set a channel’s destination
address, just like the main Destination Address Register.
NA