CY7C027/028
CY7C037/038
Document #: 38-06042 Rev. *A Page 16 of 19
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)
[45]
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
[47]
Reset Right INT
R
Flag X X X X X X L L 7FFF H
[46]
Set Left INT
L
Flag X X X X L
[46]
L L X 7FFE X
Reset Left INT
L
Flag X L L 7FFE H
[47]
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:
45. A
0L–15L
and A
0R–15R
, FFFF/FFFE for the CY7C028/038.
46. If BUSY
R
=L, then no change.
47. If BUSY
L
=L, then no change.
