UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
103 of 362
NXP Semiconductors
UM10208
Chapter 8: LPC2800 EMC
DYCS can be connected to 16-bit-wide device(s) or an even number of 8-bit-wide
devices.
10.19 Dynamic Memory RAS & CAS Delay Register (EMCDynamicRASCAS -
0x8000 8104)
The EMCDynamicRasCas Register controls the RAS and CAS latencies for the dynamic
memory. These registers 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. These registers are accessed
with one wait state.
Note: The values programmed into these registers must be consistent with the values
used to initialize the SDRAM memory device.
shows the EMCDynamicRasCas Register.
0
0
011
01
16Mx16, 4 banks, row length=13, col length=9
22:10 24:12 23
11
0
0
100
01
32Mx16, 4 banks, row length=13, col length=10
23:11 25:13 25
11
16 bit external bus low-power SDRAM address mapping (Bank, Row, Column)
0
1
000
00
2Mx8, 2 banks, row length=11, col length=9
20:10 21:11 21
-
0
1
000
01
1Mx16, 2 banks, row length=11, col length=8
19:9
20:10 -
9
0
1
001
00
8Mx8, 4 banks, row length=12, col length=9
21:10 23:12 23
11
0
1
001
01
4Mx16, 4 banks, row length=12, col length=8
20:9
22:11 21
9
0
1
010
00
16Mx8, 4 banks, row length=12, col length=10
22:11 24:13 23
11
0
1
010
01
8Mx16, 4 banks, row length=12, col length=9
21:10 23:12 23
11
0
1
011
00
32Mx8, 4 banks, row length=13, col length=10
23:11 25:13 25
11
0
1
011
01
16Mx16, 4 banks, row length=13, col length=9
22:10 24:12 23
11
0
1
100
01
32Mx16, 4 banks, row length=13, col length=10
23:11 25:13 25
11
Table 96.
Address mapping
14 12 11:9 8:7
Description
Row
addr
bits
BRC
Row
addr
bits
RBC
BA1
bit
BRC
BA1
bit
RBC
Table 97.
Dynamic Memory RAS/CAS Delay Register (EMCDynamicRasCas - 0x8000 8104)
Bit
Symbol
Description
POR Reset
Value
1:0
RAS
RAS latency (active to read/write delay):
01: One AHB HCLK cycle
10: Two AHB HCLK cycles
11: Three AHB HCLK cycles
00: Reserved
11