Table 1 – Cypress CY7C028V User Manual
Page 15
CY7C027V/027VN/027AV/028V
CY7C037V/037AV/038V
Document #: 38-06078 Rev. *B
Page 15 of 18
Table 1. Non-Contending Read/Write
Inputs
Outputs
CE
R/W
OE
UB
LB
SEM
I/O
9
–I/O
17
I/O
0
–I/O
8
Operation
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)
[37]
Left Port
Right Port
Function
R/W
L
CE
L
OE
L
A
0L–14L
INT
L
R/W
R
CE
R
OE
R
A
0R–14R
INT
R
Set Right INT
R
Flag
L
L
X
7FFF
X
X
X
X
X
L
Reset Right INT
R
Flag
X
X
X
X
X
X
L
L
7FFF
H
Set Left INT
L
Flag
X
X
X
X
L
L
L
X
7FFE
X
Reset Left INT
L
Flag
X
L
L
7FFE
H
X
X
X
X
X
Table 3. Semaphore Operation Example
Function
I/O
0
–I/O
17
Left
I/O
0
–I/O
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
37. A
0L–15L
and A
0R–15R
,FFFF/FFFE for the CY7C028V/038V.
38. If BUSY
R
=L, then no change.
39. If BUSY
L
=L, then no change.