UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
96 of 362
NXP Semiconductors
UM10208
Chapter 8: LPC2800 EMC
10.6 Dynamic Memory Read Configuration Register
(EMCDynamicReadConfig - 0x8000 8028)
The EMCDynamicReadConfig Register controls the dynamic memory read strategy. This
register must only be modified during system initialization. This register is accessed with
one wait state.
shows the EMCDynamicReadConfig Register.
10.7 Dynamic Memory Percentage Command Period Register
(EMCDynamictRP - 0x8000 8030)
The EMCDynamicTRP Register controls the precharge command period, t
RP
. This
register must only be modified during system initialization. This value is normally found in
SDRAM data sheets as t
RP
. This register is accessed with one wait state.
shows the EMCDynamicTRP Register.
Table 83.
Dynamic Memory Read Configuration Register (EMCDynamicReadConfig -
address 0x8000 8028)
Bit
Symbol
Value Description
POR
Reset
Value
1:0
Read data
strategy
00
Clock out delayed strategy, using CLKOUT (command not
delayed, clock out delayed). POR reset value.
00
01
Command delayed strategy, using AHBHCLKDELAY
(command delayed, clock out not delayed).
10
Command delayed strategy plus one clock cycle, using AHB
HCLKDELAY (command delayed, clock out not delayed).
11
Command delayed strategy plus two clock cycles, using AHB
HCLKDELAY (command delayed, clock out not delayed).
31:2
-
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-
Table 84.
Dynamic Memory Percentage Command Period Register (EMCDynamictRP -
address 0x8000 8030)
Bit
Symbol
Description
POR
Reset
Value
3:0
Precharge
command
period (t
RP
)
SDRAM initialization code should write this field with one less
than the number of AHB HCLK cycles that equals or just
exceeds the tRP 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.
-