M58LT128GST datasheet(36/98 Pages) STMICROELECTRONICS

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6 Configuration Register

M58LT128GST, M58LT128GSB

36/98

Refer to Figure 5: X-Latency and Data Output Configuration Example.

6.3

Wait Polarity Bit (CR10)

The Wait Polarity bit is used to set the polarity of the Wait signal used in Synchronous Burst

Read mode. During Synchronous Burst Read mode the Wait signal indicates whether the data

output are valid or a WAIT state must be inserted.

When the Wait Polarity bit is set to ‘0’ the Wait signal is active Low. When the Wait Polarity bit is

set to ‘1’ the Wait signal is active High.

6.4

Data Output Configuration Bit (CR9)

The Data Output Configuration bit is used to configure the output to remain valid for either one

or two clock cycles during synchronous mode.

When the Data Output Configuration Bit is ’0’ the output data is valid for one clock cycle, when

the Data Output Configuration Bit is ’1’ the output data is valid for two clock cycles.

The Data Output Configuration must be configured using the following condition:

●

tK > tKQV + tQVK_CPU

where

●

tK is the clock period

●

tQVK_CPU is the data setup time required by the system CPU

●

tKQV is the clock to data valid time.

If this condition is not satisfied, the Data Output Configuration bit should be set to ‘1’ (two clock

cycles). Refer to Figure 5: X-Latency and Data Output Configuration Example.

6.5

Wait Configuration Bit (CR8)

The Wait Configuration bit is used to control the timing of the Wait output pin, WAIT, in

Synchronous Burst Read mode.

When WAIT is asserted, Data is Not Valid and when WAIT is deasserted, Data is Valid.

When the Wait Configuration bit is Low (set to ’0’) the Wait output pin is asserted during the

WAIT state. When the Wait Configuration bit is High (set to ’1’), the Wait output pin is asserted

one data cycle before the WAIT state.

6.6

Burst Type Bit (CR7)

The Burst Type bit determines the sequence of addresses read during Synchronous Burst

Reads.

The Burst Type bit is High (set to ’1’), as the memory outputs from sequential addresses only.

See Table 11: Burst Type Definition, for the sequence of addresses output from a given starting

address in sequential mode.

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