UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
98 of 362
NXP Semiconductors
UM10208
Chapter 8: LPC2800 EMC
10.10 Dynamic Memory Last Data Out to Active Time Register
(EMCDynamictAPR - 0x8000 803C)
The EMCDynamicTAPR Register controls the last-data-out to active command time, t
APR
.
This register should only be modified during system initialization, or when there are no
current or outstanding transactions. This can be ensured by waiting until the EMC is idle,
and then entering low-power or disabled mode. This value is normally found in SDRAM
data sheets as tAPR. This register is accessed with one wait state.
shows the EMCDynamicTAPR Register.
10.11 Dynamic Memory Data-in to Active Command Time Register
(EMCDynamictDAL - 0x8000 8040)
The EMCDynamicTDAL Register controls the data-in to active command time, t
DAL
. This
register should only be modified during system initialization, or when there are no current
or outstanding transactions. This can be ensured by waiting until the EMC is idle, and then
entering low-power or disabled mode. This value is normally found in SDRAM data sheets
as t
DAL
, or t
APW
. This register is accessed with one wait state.
shows the bit assignments for the EMCDynamicTDAL Register.
Table 87.
Memory Last Data Out to Active Time Register (EMCDynamictAPR - address
0x8000 803C)
Bit
Symbol
Description
POR
Reset
Value
3:0
Last-data-out to
active command
time (t
APR
)
SDRAM initialization code should write this field with one less
than the number of AHB HCLK cycles that equals or just
exceeds the tAPR time specified for the dynamic memory. The
power-on reset value would select 16 AHB HCLK cycles.
0xF
31:4
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-
Table 88.
Dynamic Memory Data-in to Active Command Time Register (EMCDynamictDAL -
address 0x8000 8040)
Bit
Symbol
Description
POR
Reset
Value
3:0
Data-in to active
command (t
DAL
)
SDRAM initialization code should write this field with one less
than the number of AHB HCLK cycles that equals or just
exceeds the tDAL or tAPW time specified for the dynamic
memory. The power-on reset value would select 16 AHB HCLK
cycles.
0xF
31:4
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-