Intel cPCI-7200 - Manual (Page 37)

Operation Theory
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Operation Theory
In PCI-7200, there are four data transfer modes can be used for digital I/O
access and control, these modes are:
1. Direct Program Control: the digital inputs and outputs can be read/written
and controlled by its corresponding I/O port address directly.
2. Internal Timer Pacer Mode: the digital input and output operations are
paced by an internal timer pacer and are transferred by bus mastering DMA.
3. External Clock Mode: the digital input operation is clocked by external
I_REQ strobe and transferred by bus mastering DMA.
4. Handshaking: through REQ and ACK signals, the digital I/O can have
simple handshaking data transfers.
4.1 Direct Program Control
Digital I/O operations can be controlled by I/O port BASE+10 for digital input
and BASE+14 for digital output.
The I/O port address BASE is assigned by system BIOS, please refer to
Section 5 for a more detailed description.
The digital OUT operation is:
outport (BASE+14, 0xAAAAAAAA) // (A : 0 to F)
The digital IN operation is:
value = inport (BASE+10)
// The input status is save in the
// value variable