CDA CD 60 Especificações descarregar pdf (Página 61)

PCI CD and PCI CDa

Document Number: 008-00965-06 EDT Public Revision: I December 2004

Template: edt.dot

Page 61

Hardware Interface Protocol

This section describes how to connect your device to an PCI CD/CDa interface, including the electrical

characteristics of the signal, the signal descriptions, the timing specifications, and the connector pinout.

Electrical Interface

The PCI CD/CDa uses differential data transmission to transmit data at very high rates over long

distances through noisy environments. Differential transmission nullifies the effects of ground shifts

and noise. These effects appear as common mode voltages on the transmission line and are rejected by

the receiver. A typical balanced differential circuit is shown below.

driver

twisted pair cable

receiver

100 ohm typ.

Figure 2. Balanced Differential Circuit

The interface is implemented with 32 signals, each implemented as a differential pair of wires.

RS422

The PCI CD-20 DMA interface protocol uses RS422 signal levels. RS422 is defined by the Electronic

Industries Association to provide robust high-speed data transmission. It allows signaling rates up to

10 MHz for short cables of up to 12 meters (40 feet) and cables of up to 1219 meters (4000 feet) at 100

KHz, as shown in Figure 3.

For further information, see the EIA RS422-A standard, Electrical Characteristics of Balanced Voltage

Digital Interface Circuits, Dec. 1978, available from the Electronic Industries Association, Engineering

Department, 2001 Eye St. N.W., Washington, D.C. 20006.

10m

10k

90k

100k

1M 10M

100m

1,000m

1,200m

10,000m

Cable length (meters)

Data rate (bits/second)

Figure 3. RS422 Data Signalling Rate and Cable Length

1 2 ... 56 57 58 59 60 61 62 63 64 65 66 ... 90 91

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CDA CD 60 Especificações Página 61