Cypress CY7C145 - Manual (Page 15)

CY7C145, CY7C144
Document #: 38-06034 Rev. *D Page 15 of 21
Table 3. Non-Contending Read/Write
Inputs Outputs
CE R/W OE SEM I/O
0 −7/8
Operation
H X X H High Z Power-Down
H H L L Data Out Read Data in Semaphore
X X H X High Z I/O Lines Disabled
H X L Data In Write to Semaphore
L H L H Data Out Read
L L X H Data In Write
L X X L Illegal Condition
Table 4. Interrupt Operation Example (assumes BUSY
L
= BUSY
R
= HIGH)
Function Left Port Right Port
R/W CE OE A
0 −12
INT R/W CE OE A
0 −12
INT
Set Left INT X X X X L L L X 1FFE X
Reset Left INT X L L 1FFE H X L L X X
Set Right INT L L X 1FFF X X X X X L
Reset Right INT X X X X X X L L 1FFF H
Table 5. Semaphore Operation Example
Function I/O
0-7/8
Left I/O
0-7/8
Right Status
No action 1 1 Semaphore free
Left port writes semaphore 0 1 Left port obtains semaphore
Right port writes 0 to semaphore 0 1 Right side is denied access
Left port writes 1 to semaphore 1 0 Right port is granted access to semaphore
Left port writes 0 to semaphore 1 0 No change. Left port is denied access
Right port writes 1 to semaphore 0 1 Left port obtains semaphore
Left port writes 1 to semaphore 1 1 No port accessing semaphore address
Right port writes 0 to semaphore 1 0 Right port obtains semaphore
Right port writes 1 to semaphore 1 1 No port accessing semaphore
Left port writes 0 to semaphore 0 1 Left port obtains semaphore
Left port writes 1 to semaphore 1 1 No port accessing semaphore
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