UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
234 of 362
NXP Semiconductors
UM10208
Chapter 17: LPC2800 USB Device
8.30 USB DMA Engine Register Descriptions
All USB DMA Engine registers are 32 bits wide and are aligned at word address
boundaries. As for the USB Controller, the following tables are arranged in a reasonable
order for learning about the DMA Engine, rather than in ascending address order. USB
DMA registers are not affected by a USB Bus Reset, so the following tables have only one
Reset column.
8.31 USB DMA Control Register (UDMACtrl - 0x8004 0400)
8.32 USB DMA Software Reset Register (UDMASoftRes - 0x8004 0404)
This write-only register enables software to reset one or both DMA channels. When a
channel is software reset: all of the registers for the channel are cleared to their Reset
values, DMA activity stops except that if a transfer is in progress at the time of the reset, it
is completed, and the DMA channel’s FIFO is cleared.
Table 260. USB DMA Control Register (UDMACtrl - 0x8004 0400)
Bit
Symbol
Description
Reset
value
0
UDMA_EN A 1 in this bit enables USB DMA operation. Changing this bit from 1
to 0 will suspend any DMA operations that are active at the time.
Changing this bit back to 1 thereafter will resume those DMA
operations.
0
31:1
-
Reserved, software should not write ones to reserved bits. The values
read from reserved bits is not defined.
-
Table 261. USB DMA Software Reset Register (UDMASoftRes - 0x8004 0404)
Bit
Symbol
Description
0
RSTCH0
Write a 1 to this bit to reset DMA channel 0.
1
RSTCH1
Write a 1 to this bit to reset DMA channel 1.
31:2
-
Reserved, software should not write ones to reserved bits.