DR
AFT
DR
AFT
DRAFT
DR
D
RAFT
DRAFT
DRA
FT DRAF
D
RAFT DRAFT DRAFT DRAFT DRAFT D
DRAFT
D
RAFT DRA
FT DRAFT DRAFT DRAFT DRA
UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
264 of 571
NXP Semiconductors
UM10316
Chapter 18: LPC29xx SPI0/1/2
3.7 SPI DMA settings register
The DMA settings register enables the DMA transfer for the receive and transmit lines and
the defines the burst mode.
Table 220. RX_FIFO_READMODE register bit description (RX_FIFO_READMODE0/1/2:
addresses 0xE004 7014 (SPI0), 0xE004 8014 (SPI1), 0xE004 9014 (SPI2))
* = reset value
Bit
Symbol
Access
Value
Description
31 to 1 reserved
R
-
Reserved; do not modify. Read as logic 0
0
RX_FIFO_PROTECT R/W
Receive-FIFO protect-mode bit
1
Enables the receive-FIFO protect mode to
protect the receive-FIFO contents from
speculative read actions
A read of the FIFO_DATA register will return
the data from the FIFO, but will not update the
FIFO’s read pointer. Speculative reads of the
FIFO_DATA register will thus not cause data
loss from the receive FIFO. After every read of
data the RX FIFO POP register needs to be
written to remove the read element from the
FIFO and to point to the next element.
0*
Disables receive-FIFO protect mode
An explicit pop of the receive FIFO is no
longer needed. Reading the FIFO_DATA
register will also update the receive FIFO’s
read pointer.
Table 221. DMA_SETTINGS register bit description (DMA_SETTINGS0/1/2: addresses
0xE004 7018 (SPI0), 0xE004 8018 (SPI1), 0xE004 9018 (SPI2))
* = reset value
Bit
Symbol
Access
Value
Description
31 to 8 reserved
R
-
Reserved; do not modify. Read as logic 0
7:5
TX_DMA_BURST
R/W
000* -
111
Defines when the SPI will request a Tx burst
DMA transfer. The DMA burst will be
requested when the transmit FIFO has this
number of free spaces (= room to hold one
element):
000 : 1 free space
001 : 4 free spaces
010 : 8 free spaces
011 : 16 free spaces
100 : 32 free spaces
101 : 64 free spaces
110 : 128 free spaces
111 : 256 free spaces