Registers & Operation Theorem
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3
Register & Operation
Theorem
In this chapter, the register format and primitive digital I/O operations of 723X
series products will be specified. The operation theorem of the digital I/O, interrupt
are introduced. Before programming or applying the 723X cards to your
applications, please go through this chapter to understand the features of the
functions.
3.1 I/O Port Base Address
The PCI-723X products function as a 32-bit PCI target device to any
master on the PCI bus. There are three types of registers on the PCI-
723X: PCI Configuration Registers (PCR), Local Configuration Registers
(LCR) and PCI-723X registers.
The PCR, which conform the PCI-bus specifications R2.1, is initialized and
controlled by the system plug & play PCI BIOS. Please refer to the PCI
BIOS specification to understand how to get information from the PCR.
The LCR is specified by the PCI bus controller (PCI-9050). It is not
necessary for users to understand the details of the LCR if you use the
software library. The base address of the LCR is assigned by the PCI PnP
BIOS. The assigned address is located at offset 14h of PCR. Please refer
to the PCI-9050’s data sheet for the detail operation of the LCR and also
the register format of the PCR. For detail information about PCI-9050, you
can download its datasheet from http:\\www.plxtech.com.
The registers of 723X series are shown in the Section 3.2. The base
address of the 723X registers are also assigned by the PCI PnP BIOS.
The assigned base address is stored at offset 18h of PCR. Therefore,
users can read the PCR to get the base address by using the BIOS
function call. Note that the PCI-723X registers are all 32 bits. The users
can access these registers by 8 bits or 16-bit I/O instructions.
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