M7020 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'M7020' PDF : 150 Pages View PDF
M7020R
Table 28. Latency of SEARCH from Instruction to SRAM Access Cycle, 68-bit, Up to 8 Devices
# of devices
Max Table Size
Latency in CLK Cycles
1 (TLSZ = 00)
32K x 68-bit
4
2–8 (TLSZ = 01)
256K x 68-bit
5
9–31 (TLSZ = 10)
992K x 68-bit
6
Table 29. Shift of SSF and SSV from SADR
HLAT
000
001
010
011
100
101
110
111
Number of CLK Cycles
0
1
2
3
4
5
6
7
68-bit SEARCH on Tables Configured as x68 Using Up To 31 M7020R Devices
The hardware diagram of the search subsystem of
31 devices is shown in Figure 27, page 48. Each
of the four blocks in the diagram represents eight
M7020R devices (except the last, which has seven
devices). The diagram for a block of eight devices
is shown in Figure 28, page 49. The following are
the parameters programmed into the 31 devices:
– First thirty devices (devices 0–29):
CFG = 00000000, TLSZ = 10, HLAT = 001,
LRAM = 0, and LDEV = 0.
– Thirty-first device (device 30):
CFG = 00000000, TLSZ = 10, HLAT = 001,
LRAM = 1, and LDEV = 1.
Note: All 31 devices must be programmed with the
same values for TLSZ and HLAT. Only the last de-
vice in the table must be programmed with
LRAM = 1 and LDEV = 1 (Device 30 in this case).
All other upstream devices must be programmed
with LRAM = 0 and LDEV = 0 (Devices 0 through
29 in this case).
The timing diagrams referred to in this paragraph
reference the HIT/MISS assumptions defined in
Table 30, page 47. For the purpose of illustrating
the timings, it is further assumed that there is only
one device with a matching entry in each of the
blocks. Figure 30, page 51 shows the timing dia-
gram for a SEARCH command in the 68-bit-con-
figured table of 31 devices for each of the eight
devices in Block Number 0. Figure 31, page 52
shows a timing diagram for a SEARCH command
in the 68-bit-configured table of 31 devices for the
all the devices in Block Number 1 (above the win-
ning device in that block). Figure 32, page 53
shows the timing diagram for the globally winning
device (defined as the final winner within its own
and all blocks) in Block Number 1. Figure 33, page
54 shows the timing diagram for all the devices be-
low the globally winning device in Block Number 1.
Figure 34, page 55, Figure 35, page 56, and Fig-
ure 36, page 57 show the timing diagrams of the
devices above the globally winning device, the glo-
bally winning device, and the devices below the
globally winning device, respectively, for Block
Number 2. Figure 37, page 58, Figure 38, page 59,
Figure 39, page 60, and Figure 40, page 61 show
the timing diagrams of the devices above globally
winning device, the globally winning device, and
the devices below the globally winning device ex-
cept the last device (Device 30), respectively, for
Block Number 3.
46/150
Share Link: 
