UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
93 of 362
NXP Semiconductors
UM10208
Chapter 8: LPC2800 EMC
10.2 EMC Status Register (EMCStatus - 0x8000 8004)
The read-only EMCStatus Register provides EMC status information.
the bit assignments for the EMCStatus Register.
10.3 EMC Configuration Register (EMCConfig - 0x8000 8008)
The EMCConfig Register configures the operation of the memory controller. This register
should be modified only during system initialization, or when there are no current or
outstanding transactions. This can be ensured by waiting until the EMCStatus Register
indicates "not Busy" and "write buffers empty", and then entering low-power or disabled
mode. This register is accessed with one wait state.
shows the EMCConfig
Register.
Table 79.
EMC Status Register (EMCStatus - address 0x8000 8004)
Bit
Symbol
Description
POR
Reset
Value
0
Busy
This read-only bit is 1 if the EMC is busy performing memory
transactions, commands, auto-refresh cycles, or is in self-refresh
mode. Read this bit, and if necessary wait for it to be 0, before
setting low-power or disabled mode in the EMCControl Register.
Power-on reset sets this bit because it sets self-refresh mode.
After a warm reset, this bit reflects whether self-refresh mode is in
effect.
1
1
Write Buffer
Status
This read-only bit is 1 if write buffers are enabled, and they
contain data from a previous write operation. Read this bit, and if
necessary wait for it to be 0, before setting low-power or disabled
mode in the EMCControl Register. Power-on reset clears this bit.
0
2
Self-Refresh
Acknowledge
This read-only bit is 1 if the EMC is in self-refresh mode.
Power-on reset sets this bit because it sets self-refresh mode.
Software can request self-refresh mode in the Dynamic Memory
Control Register, or in the EMCMisc Register (
). This bit lags whichever request is used by a short
hardware-handshaking time.
1
31:3
-
Reserved. The value read from a reserved bit is not defined.
-
Table 80.
EMC Configuration Register (EMCConfig - address 0x8000 8008)
Bit
Symbol
Description
POR
Reset
Value
0
Bigendian
After a power-on reset this bit is 0. Write a 1 to this bit to select
"Big-endian" mode.
0
7:1
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-
8
CLKOUTdiv2
When this bit is 0, as it is after a power-on reset, the CLKOUT
signal to dynamic memory is driven from the AHB HCLK signal. Do
not set this bit.
0
31:9 -
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-