Cypress CY7C0251AV - Manual (Page 7)

CY7C024AV/024BV/025AV/026AV
CY7C0241AV/0251AV/036AV
Document #: 38-06052 Rev. *J Page 7 of 19
Table 1. Non-Contending Read/Write
Inputs Outputs
Operation
CE R/W OE UB LB SEM IO
9
–IO
17
IO
0
–IO
8
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 D
IN0
into Semaphore Flag
X X H H L Data In Data In Write D
IN0
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 BUSY
L
= BUSY
R
= HIGH) [10]
Left Port Right Port
Function R/W
L
CE
L
OE
L
A
0L–13L
INT
L
R/W
R
CE
R
OE
R
A
0R–13R
INT
R
Set Right INT
R
Flag L L X FFF [13] X X X X X L [12]
Reset Right INT
R
Flag X X X X X X L L FFF (or 1/3FFF) H
[11]
Set Left INT
L
Flag X X X X L
[11]
L L X 1FFE (or 1/3FFE) X
Reset Left INT
L
Flag X L L 1FFE [13] H [12] X X X X X
Table 3. Semaphore Operation Example
Function IO
0
–IO
17
Left IO
0
–IO
17
Right 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 BUSY
R
=L, then no change.
12. If BUSY
L
=L, then no change.
13. See Functional Description on page 5 for specific addresses by device.
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