Intel IXP45X Developer's Manual page 636

Register
Bits Name
RTW: Read to Write turnaround period in MCLK periods. This value is
computed by using the CAS Latency (t
the JEDEC/Vendor specification) using the following equation:
Equation 7. RTW = t
NOTE: t
22:2
programmed value of 000
RTW
0
For example, a device specification yields that t
the suggested EDP value of 2 mclks is used.
Thus, RTW = 2.5 + 2 + 1 = 5.5, round up to 6 mclks, so a value of
0110
NOTE:
they are to open pages.
RESERVED. A value of 0
19 (Reserved)
network processors.
18:1
(Reserved)
7
RFC: Auto Refresh Command Period in MCLK periods. This value is
computed by using the t
JEDEC/Vendor specification) using the following equation:
Equation 8. RFC = t
16:1
RFC
NOTE: t
2
For example, a device specification yields that t
device speed is 133MHz, so the mclk period is 7.5ns).
t
RFC
Thus, RFC = 16-1 = 15, so a value of 01111
11:0 RESERVED. A value of 000
(Reserved)
9 network processors.
RC: Active to Active and Active to Auto Refresh command period in
MCLK periods. This value is computed by using the t
the device (provided in the JEDEC/Vendor specification) using the
following equation:
Equation 9. RC = t
08:0
RC
4
NOTE: t
For example, a device specification yields that t
device speed is 133MHz, so the mclk period is 7.5ns).
t
RC
Thus, RC = 9-1 = 8, so a value of 01000
03 (Reserved)
WTRD: Write-to-Read turnaround period in MCLK periods. This value
is computed by using the CAS Latency (t
command delay (t
JEDEC/Vendor specification) using the following equation:
02:0 Equation 10. WTRD = t
WTRD
0
NOTE: t
For example, a device specification yields that t
t
WTR
Thus, WTRD = 2.5 + 1= 3.5, round up to 4 mclks, so a value of 100
should be programmed.
® ®
Intel IXP45X and Intel IXP46X Product Line of Network Processors
Developer's Manual
636
® ®
Intel IXP45X and Intel
DDRI SDRAM Control Register 1 - SDCR1 (External Version) (Sheet 2 of 2)
Description
CAS
must be converted to mclks for this equation. A
CAS
represents a value of 8
2
should be programmed.
2
The MCU allows for back-to-back reads, so long as
must be used for the IXP45X/IXP46X
2
measured for the device (provided in the
RFC
RFC
must be converted to mclks for this equation.
RFC
= (120ns / 7.5ns) = 16 mclks.
must be used for the IXP45X/IXP46X
2
- 1
RC
must be converted to mclks for this equation.
RC
= (65ns / 7.5ns) = 8.67, round up to 9 mclks.
) measured for the device (provided in the
WTR
CAS
and t must be converted to mclks for this equation.
CAS WTR
is 1 mclk.
IXP46X Product Line of Network Processors—Memory Controller
) for the device (provided in
CAS
+ EDP + 1
.
10
is 2.5 mclks and
CAS
- 1
is 120ns (and the
RFC
should be programmed.
2
measured for
RC
is 65ns (and the
RC
should be programmed.
2
)and internal Write to Read
CAS
+ t
WTR
is 2.5 mclks and
CAS
Default Access
000 RW
2
0 RW
2
RO
0 0000 RW
2
000 RW
2
0 0000 RW
2
000 RW
2
2
August 2006
Order Number: 306262-004US