ADVANCE
S27KL0641, S27KS0641
Table 5.4 Configuration Register 0 Bit Assignments (Continued)
CR0 Bit
Function
Settings (Binary)
0000 - 5 Clock Latency
0001 - 6 Clock Latency (default)
0010 - Reserved
0011 - Reserved
0100 - Reserved
...
7-4
Initial Latency
1101 - Reserved
1110 - 3 Clock Latency
1111 - 4 Clock Latency
0 - Variable Latency - 1 or 2 times Initial Latency depending on RWDS during
CA cycles.
1 - Fixed 2 times Initial Latency (default)
3
2
Fixed Latency Enable
Hybrid Burst Enable
0: Wrapped burst sequences to follow hybrid burst sequencing
1: Wrapped burst sequences in legacy wrapped burst manner (default)
00 - 128 bytes
01 - 64 bytes
10- 16 bytes
1-0
Burst Length
11 - 32 bytes (default)
5.2.1.1
Wrapped Burst
A wrapped burst transaction accesses memory within a group of words aligned on a word boundary matching the length of the
configured group. Wrapped access groups can be configured as 16, 32, 64, or 128 bytes alignment and length. During wrapped
transactions, access starts at the Command-Address selected location within the group, continues to the end of the configured word
group aligned boundary, then wraps around to the beginning location in the group, then continues back to the starting location.
Wrapped bursts are generally used for critical word first instruction or data cache line fill read accesses.
5.2.1.2
Hybrid Burst
The beginning of a hybrid burst will wrap within the target address wrapped burst group length before continuing to the next half-
page of data beyond the end of the wrap group. Continued access is in linear burst order until the transfer is ended by returning CS#
high. This hybrid of a wrapped burst followed by a linear burst starting at the beginning of the next burst group, allows multiple
sequential address cache lines to be filled in a single access. The first cache line is filled starting at the critical word. Then the next
sequential line in memory can be read in to the cache while the first line is being processed.
Table 5.5 CR0[2] Control of Wrapped Burst Sequence
Bit
Default Value
Name
Hybrid Burst Enable
2
1
CR[2]= 0: Wrapped burst sequences to follow hybrid burst sequencing
CR[2]= 1: Wrapped burst sequences in legacy wrapped burst manner
Document Number: 001-97964 Rev. *E
Page 10 of 29
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