CY7C027-20ACT Cypress Semiconductor, CY7C027-20ACT Datasheet - Page 16

• Manufacturer Part Number: CY7C027-20ACT
• Manufacturer: Cypress Semiconductor

output register to prevent the semaphore from changing state
during a write from the other port. If both ports attempt to access
the semaphore within t
Table 1. Non-Contending Read/Write
Table 2. Interrupt Operation Example (assumes BUSY
Table 3. Semaphore Operation Example
Document #: 38-06042 Rev. *D
Set Right INT
Reset Right INT
Set Left INT
Reset Left INT
No action
Left port writes 0 to semaphore
Right port writes 0 to semaphore
Left port writes 1 to semaphore
Left port writes 0 to semaphore
Right port writes 1 to semaphore
Left port writes 1 to semaphore
Right port writes 0 to semaphore
Right port writes 1 to semaphore
Left port writes 0 to semaphore
Left port writes 1 to semaphore
Notes
23. A
24. If BUSY
25. If BUSY
CE
H
H
H
X
X
X
X
L
L
L
L
L
L
L
L
0L–15L
Function
R
L
and A
R/W
= L, then no change.
= L, then no change.
H
H
H
H
H
X
X
X
X
X
L
Function
L
L
L
Flag
R
L
0R–15R
Flag
R
Flag
Flag
OE
, FFFF/FFFE for the CY7C028/038.
X
X
X
X
X
H
X
X
X
X
L
L
L
L
L
Inputs
SPS
R/W
X
X
X
L
UB
of each other, the semaphore is
X
H
H
H
X
X
H
X
H
X
L
L
L
L
L
L
CE
I/O
X
X
L
L
L
LB
0
X
H
H
H
X
X
H
X
H
X
L
L
L
L
L
–I/O
1
0
0
1
1
0
1
1
1
0
1
OE
17
X
X
X
L
Left I/O
Left Port
L
SEM
H
H
H
H
H
H
H
H
X
L
L
L
L
L
L
0
High Z
High Z
Data In
High Z
Data In
Data Out
High Z
Data Out
High Z
Data Out
Data Out
Data In
Data In
A
–I/O
7FFF
7FFE
0L–14L
L
X
X
1
1
1
0
0
1
1
0
1
1
1
I/O
17
= BUSY
Right
9
–I/O
17
R
definitely obtained by one side or the other, but there is no
guarantee which side controls the semaphore.
Semaphore free
No change. Right side has no write access to semaphore
Right port obtains semaphore token
No change. Left port has no write access to semaphore
Left port obtains semaphore token
Semaphore free
Right port has semaphore token
Semaphore free
Semaphore free
Left port has semaphore token
Left port has semaphore token
= HIGH)
Outputs
INT
H
L
X
X
[24]
[25]
L
High Z
High Z
High Z
Data In
Data In
High Z
Data Out
Data Out
High Z
Data Out
Data Out
Data In
Data In
[23]
R/W
I/O
X
X
X
L
0
R
–I/O
CE
8
X
X
L
L
R
Deselected: Power Down
Deselected: Power Down
Write to Upper Byte Only
Write to Lower Byte Only
Write to Both Bytes
Read Upper Byte Only
Read Lower Byte Only
Read Both Bytes
Outputs Disabled
Read Data in Semaphore Flag
Read Data in Semaphore Flag
Write D
Write D
Not Allowed
Not Allowed
Status
OE
X
L
X
X
Right Port
R
IN0
IN0
into Semaphore Flag
into Semaphore Flag
Operation
A
7FFE
7FFF
0R–14R
CY7C027/028
CY7C037/038
X
X
Page 16 of 19
INT
H
L
[25]
X
X
[24]
R
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