Intel cPCI-7200 Manual do Utilizador descarregar pdf (Página 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

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Intel cPCI-7200 Manual do Utilizador Página 37