UM10503
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User manual
Rev. 1.3 — 6 July 2012
475 of 1269
NXP Semiconductors
UM10503
Chapter 21: LPC43xx External Memory Controller (EMC)
21.7.3 EMC Configuration register
The Config register configures the operation of the memory controller. It is recommended
that this register is 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 register is accessed with one wait state.
21.7.4 Dynamic Memory Control register
The DynamicControl register controls dynamic memory operation. The control bits can be
altered during normal operation.
2
SA
Self-refresh acknowledge. This bit indicates the operating
mode of the EMC:
1
0
Normal mode
1
Self-refresh mode (POR reset value).
31:3 -
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-
Table 355. EMC Status register (STATUS - address 0x4000 5004) bit description
Bit
Symbol
Value
Description
Reset
value
Table 356. EMC Configuration register (CONFIG - address 0x4000 5008) bit description
Bit
Symbol
Value Description
Reset
value
0
EM
Endian mode.
0
0
Little-endian mode (POR reset value).
1
Big-endian mode.
On power-on reset, the value of the endian bit is 0. All data must
be flushed in the EMC before switching between little-endian and
big-endian modes.
7:1
-
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-
8
CR
Clock Ratio. CCLK: CLKOUT[1:0] ratio:
0
0
1:1 (POR reset value)
1
1:2
This bit must contain 0 for proper operation of the EMC.
31:9 -
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-
Table 357. Dynamic Control register (DYNAMICCONTROL - address 0x4000 5020) bit
description
Bit
Symbol
Value Description
Reset
value
0
CE
Dynamic memory clock enable.
0
0
Clock enable of idle devices are deasserted to save power (POR
reset value).
1
All clock enables are driven HIGH continuously.