Kontron PCI-AOB16/12, User Manual

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PCI-AOB8/12 (16/12) User’s Guide
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Programming the Digital I/O
Circuit
The digital I/O circuit is comprised of an Intel 8255, a direction control latch, and four
bi-directional buffers with 10K pull-ups. Please refer to the 8255-5 specification in appendix A
for a detailed description of the PPI.
Table 5-3. I/O Address Table for Digital
The circuit is designed to use the PPI in mode 0 wherein:
J There are two 8-bit ports (A and B) and two 4-bit ports (C Hi and C Lo)
J Any port can be configured as an input or an output
J Outputs are latched
J Inputs are not latched
Address Assignment Operation
Base A20 Port A Read/Write
Base A21 Port B Read/Write
Base A22 Port C Read/Write
Base A23 Control Read/Write