M50LPW080 datasheet(14/44 Pages) STMICROELECTRONICS

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M50LPW080

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Table 7. LPC Bus Read Field Definitions

Figure 6. LPC Bus Read Waveforms

Clock

Cycle

Number

Clock

Cycle

Count

Field

LAD0-

LAD3

Memory

I/O

Description

START

0000b

On the rising edge of CLK with LFRAME Low, the contents

of LAD0-LAD3 must be 0000b to indicate the start of a

LPC cycle.

CYCTYPE

+ DIR

010Xb

Indicates the type of cycle. Bits 3:2 must be 01b. Bit 1

indicates the direction of transfer: 0b for read. Bit 0 is don’t

care (X).

3-10

ADDR

XXXX

A 32-bit address phase is transferred starting with the most

significant nibble first. A23-A31 must be set to 1. A22 = 1

for Array, A22 = 0 for registers access. For A20-A21

values, see Table 3..

TAR

1111b

The host drives LAD0-LAD3 to 1111b to indicate a

turnaround cycle.

TAR

1111b

(float)

The LPC Flash Memory takes control of LAD0-LAD3

during this cycle.

13-14

WSYNC

0101b

The LPC Flash Memory drives LAD0-LAD3 to 0101b

(short wait-sync) for two clock cycles, indicating that the

data is not yet available. Two wait-states are always

included.

RSYNC

0000b

The LPC Flash Memory drives LAD0-LAD3 to 0000b,

indicating that data will be available during the next clock

cycle.

16-17

DATA

XXXX

Data transfer is two CLK cycles, starting with the least

significant nibble.

TAR

1111b

The LPC Flash Memory drives LAD0-LAD3 to 1111b to

indicate a turnaround cycle.

TAR

1111b

(float)

N/A

The LPC Flash Memory floats its outputs, the host takes

control of LAD0-LAD3.

AI04429

CLK

LFRAME

LAD0-LAD3

Number of

clock cycles

START

CYCTYPE

+ DIR

ADDR

TAR

SYNC

DATA

TAR

1182322

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