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Manual PCIe-DIO-24HC PCI Express Digital I/O w/CTR
Chapter 5: Programming
These cards are I/O-mapped devices that are easily configured from any language and
any language can easily perform digital I/O through the card's ports. This is especially
true if the form of the data is byte or word wide. All references to the I/O ports would be
in absolute port addressing.
Developing Your Application Software
If you wish to gain a better understanding of the programs installed with the software
package, then the information in the following paragraphs will be of interest to you.
A total of 22 register locations are used by this card
Address
Port Assignment
Operation
Base Address
PA Group 0
Read/Write
Base A1
PB Group 0
Read/Write
Base A2
PC Group 0
Read/Write
Base A3
Control byte
Write Only
Base AC
Enable/Disable Buffer
Write Only
Base AD
Disable Interrupts
Write Only
Base AE
Enable Interrupts
Write Only
Base AF
Clear Interrupt latch
Write Only
Base A10
Counter/Timer A0
Read/Write
Base A11
Counter/Timer A1
Read/Write
Base A12
Counter/Timer A2
Read/Write
Base A13
Counter/Timer A Control
Read/Write
Base A14
Counter/Timer B0
Read/Write
Base A15
Counter/Timer B1
Read/Write
Base A16
Counter/Timer B2
Read/Write
Base A17
Counter/Timer B Control
Read/Write
Base A18
Counter/Timer C0
Read/Write
Base A19
Counter/Timer C1
Read/Write
Base A1A
Counter/Timer C2
Read/Write
Base A1B
Counter/Timer C Control
Read/Write
Base A1C
Interrupt Enables
Read/Write
Base A1D
Interrupt Status
Read Only
Table 5-1: Address Assignment Table
8255
These cards use an 8255 PPI to provide a total of 24 bits input/output capability. The
card is designed to use the PPI in Mode 0 wherein:
1. There are two 8-bit groups (A and B) and two 4-bit groups (C Hi and C Lo).
2. Any port can be configured as an input or an output.
3. Outputs are latched.
4. Inputs are not latched.
