Cypress CY7C024AV, CY7C026AV Non-Contending Read/Write Inputs Outputs Operation, IO 0 -IO, Status

CY7C024AV/024BV/025AV/026AV

CY7C0241AV/0251AV/036AV

Table 1. Non-Contending Read/Write

Inputs

Outputs

Operation

CE

R/W

OE

UB

LB

SEM

IO9–IO17

IO0–IO8

H

X

X

X

X

H

High Z

High Z

Deselected: Power Down

X

X

X

H

H

H

High Z

High Z

Deselected: Power Down

L

L

X

L

H

H

Data In

High Z

Write to Upper Byte Only

L

L

X

H

L

H

High Z

Data In

Write to Lower Byte Only

L

L

X

L

L

H

Data In

Data In

Write to Both Bytes

L

H

L

L

H

H

Data Out

High Z

Read Upper Byte Only

L

H

L

H

L

H

High Z

Data Out

Read Lower Byte Only

L

H

L

L

L

H

Data Out

Data Out

Read Both Bytes

X

X

H

X

X

X

High Z

High Z

Outputs Disabled

H

H

L

X

X

L

Data Out

Data Out

Read Data in Semaphore Flag

X

H

L

H

H

L

Data Out

Data Out

Read Data in Semaphore Flag

H

X

X

X

L

Data In

Data In

Write DIN0 into Semaphore Flag

X

X

H

H

L

Data In

Data In

Write DIN0 into Semaphore Flag

L

X

X

L

X

L

Not Allowed

L

X

X

X

L

L

Not Allowed

Table 2. Interrupt Operation Example (assumes

L =

R = HIGH)[10]

BUSY

BUSY

Left Port

Right Port

Function

A0L–13L

A0R–13R

R/W

L

CEL

OEL

INTL

R/WR

CER

OER

INTR

Set Right

INT

R Flag

L

L

X

FFF[13]

X

X

X

X

X

L[12]

Reset Right

Flag

X

X

X

X

X

X

L

L

FFF (or 1/3FFF)

H[11]

INT

R

Set Left

INT

Flag

X

X

X

X

L[11]

L

L

X

1FFE (or 1/3FFE)

X

L

Reset Left

INT

L Flag

X

L

L

1FFE[13]

H[12]

X

X

X

X

X

Table 3. Semaphore Operation Example

Function

IO0–IO17Left

IO0–IO17Right

Status

No action

1

1

Semaphore-free

Left port writes 0 to semaphore

0

1

Left Port has semaphore token

Right port writes 0 to semaphore

0

1

No change. Right side has no write access to semaphore

Left port writes 1 to semaphore

1

0

Right port obtains semaphore token

Left port writes 0 to semaphore

1

0

No change. Left port has no write access to semaphore

Right port writes 1 to semaphore

0

1

Left port obtains semaphore token

Left port writes 1 to semaphore

1

1

Semaphore-free

Right port writes 0 to semaphore

1

0

Right port has semaphore token

Right port writes 1 to semaphore

1

1

Semaphore free

Left port writes 0 to semaphore

0

1

Left port has semaphore token

Left port writes 1 to semaphore

1

1

Semaphore-free

Notes

10.See Functional Description on page 5 for specific highest memory locations by device.

11.If BUSYR=L, then no change.

12.If BUSYL=L, then no change.

13.See Functional Description on page 5 for specific addresses by device.

Document #: 38-06052 Rev. *J Page 7 of 19

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