M7010R datasheet(20/67 Pages) STMICROELECTRONICS

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M7010R

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The Command Register

Table 10. Command Register Field Descriptions

Field

Range

Initial Value

Description

SRST

[0]

Software Reset. If '1,' this bit resets the device, with the same effect as the

hardware reset. Internally, it generates a reset pulse lasting for eight CLK

cycles. This bit automatically resets to a '0' during the reset cycle.

DEVE

[1]

Device Enable. If '0,' it keeps the SRAM bus (SADR, WE_L, CE_L, OE_L,

and ALE_L), SSF, and SSV signals in a tri-state condition and forces the

cascade interface output signals LHO[1:0] and BHO[2:0] to '0.' It also keeps

the DQ Bus in Input mode. The purpose of this bit is to make sure that there

is no bus contention when the devices power-up in the system.

TLSZ

[3:2]

Table Size. The host ASIC must program this field to configure the chips into

a table of a certain size. This field affects the pipeline latency of the SEARCH

and LEARN operations as well as the READ and WRITE accesses to the

SRAM (SADR[21:0], CE_L, OE_L, WE_L, ALE_L, SSV, SSF, and ACK).

Once programmed, the SEARCH latency stays constant.

Latency #

CLK Cycles

00: 1 device

01: 2-8 devices

10: 9-31

devices

11: Reserved

HLAT

[6:4]

000

Latency of Hit Signals. This field adds latency to the SSF, SSV, and ACK

signals by the following number of CLK cycles during SEARCH and ACK

during an SRAM READ access.

000: 0

100: 4

001: 1

101: 5

010: 2

110: 6

011: 3

111: 7

LDEV

[7]

Last device in the cascade. When set, this device is the last device in the

depth-cascaded table and is the default driver for the SSF and SSV signals.

In the event of a SEARCH failure, the device with this bit set drives the hit

signals as follows:

SSF = 0, SSV = 1

During non-search cycles, the device with this bit set drives the signals as

follows:

SSF = 0, SSV = 0

LRAM

[8]

Last device on this SRAM Bus. When set, this device is the last device on

the SRAM bus in the depth-cascaded table and is the default driver for the

SADR, CE_L, WE_L, and ALE_L signals. In cycles where no M7010R

device (in a depth-cascaded table) drives these signals, the signals are

driven as follows:

SADR = 22’h3FFFFF, CE_L = 1, WE_L = 1, and ALE_L = 1.

OE_L is always driven by the device for which this bit is set.

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