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UM10503
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User manual
Rev. 2.1 — 10 December 2015
610 of 1441
NXP Semiconductors
UM10503
Chapter 23: LPC43xx/LPC43Sxx External Memory Controller (EMC)
23.7.17 Dynamic Memory Load Mode register to Active Command Time
This register enables you to program the load mode register to active command time,
tMRD. 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 value is normally found
in SDRAM data sheets as tMRD, or tRSA. This register is accessed with one wait state.
Note: This register is used for all four dynamic memory chip selects. Therefore the worst
case value for all of the chip selects must be programmed.
23.7.18 Static Memory Extended Wait register
This register is used to time long static memory read and write transfers when the
ExtendedWait (EW) bit in the StaticConfig register is set. It is recommended that this
register is modified during system initialization, or when there are no current or
outstanding transactions. However, if necessary, these control bits can be altered during
normal operation. This register is accessed with one wait state.
Table 430. Dynamic Memory Active Bank A to Active Bank B Time register (DYNAMICRRD,
address 0x4000 5054) bit description
Bit
Symbol
Description
Reset
value
3:0
TRRD
Active bank A to active bank B latency
0x0 - 0xE = n + 1 clock cycles. The delay is in EMC_CCLK cycles.
0xF = 16 clock cycles (POR reset value).
0xF
31:4
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 431. Dynamic Memory Load Mode register to Active Command Time (DYNAMICMRD,
address 0x4000 5058) bit description
Bit
Symbol
Description
Reset
value
3:0
TMRD
Load mode register to active command time.
0x0 - 0xE = n + 1 clock cycles. The delay is in EMC_CCLK cycles.
0xF = 16 clock cycles (POR reset value).
0xF
31:4
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 432. Static Memory Extended Wait register (STATICEXTENDEDWAIT, address
0x4000 5080) bit description
Bit
Symbol
Description
Reset
value
9:0
EXTENDEDWAIT Extended wait time out.
16 clock cycles (POR reset value). The delay is in EMC_CCLK
cycles.
0x0 = 16 clock cycles.
0x1 - 0x3FF = (n+1) x16 clock cycles.
0x0
31:10 -
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
-