OPTO 22 PCI-AC51, Руководство пользователя

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APPENDIX D: PCI-AC51 TECHNICAL REFERENCE
PCI-AC51 User’s Guide
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Reading the State Machine Version
Read the Version Register. All 8 bits of the register are significant to the state machine’s
implementation revision.
This register is independent of all Pamux operations. It may be read without impact to any current
operations the state machine is performing.
Reading the Switch Values
The bit positions in the register correspond to the switches on the board. A switch in the on position
reads as a zero.
Polled PCI-AC51 Operation
NOTE: All of the directions assume a byte-wide access to the card.
Performing A Pamux Bank Write
1. Wait until the Busy Bit in the Status Register is negated (zero).
2.
Write the Pamux bank address to BAR1 offset 1.
3.
Write the Pamux data to BAR1 offset 2.
4.
A write to the Start Cycle Register (BAR1, offset 3) begins a Pamux bus cycle. The data written to
the register is ignored.
5.
Read the Status Register (BAR1, offset 4) and inspect the Busy Bit (Bit 0). If the bit is one, a
Pamux cycle is in progress. Do not modify the Bank Address Register, Data Register, or the Start
Cycle Register while the busy status is asserted. Wait until the Busy Bit negates.
6.
To read the Pamux brain identification, read the Status Register (BAR1 offset 4) and mask bits 1
and 2. These bits are valid only after the Busy Bit is negated.
Performing Pamux Bank Read
1. Wait until the Busy Bit in the Status register is negated (zero).
2.
Write the Pamux bank address to the Bank Address Register (BAR1, offset 1).
3.
Read the Start Read Register (BAR1, offset 3) to start a Pamux read bus cycle. Ignore the data
read from this register (the returned data is hard coded as 0xab).
4.
Read the Status Register (BAR1, offset 4) and inspect the Busy Bit (Bit 0). If the bit is one
(asserted), a Pamux cycle is in progress. Wait until the Busy Bit negates (zero).
5. Read the Pamux data from the Data Register (BAR1, offset 2).
NOTE: Only specific Pamux brain versions support the ID function.