MCC MIIC-203 Guía de usuario descargar pdf (Pagina 15)

standard I

C Bus connector, you may want to cut off one end of the cable and add a

connector compatible with your target system. Additional I

C Interface Cables,

Clip-Lead Cables, and modular connectors are available from MCC (see Appendix

A).

2.1 Interrupt (/INT) Signal Connector

The Interrupt (/INT) signal is an extra pin found on some I

C devices. The /INT

signal allows a slave-only device to attract the attention of a bus master device by

lowering the /INT signal to a logical low voltage level.

The iPort/USB provides an open-drain /INT signal which can be connected to a

corresponding pin on a master or slave device. The /INT signal allows the

iPort/USB to participate in interrupt signaling between master or slave devices.

An interrupt output (/INT=low) is generated upon receiving an iNterrupt Assert

command from the host computer. The interrupt signal is released (/INT = high)

when the iPort/USB is addressed as an I

C Bus slave device, or an iNterrupt Release

command is received from the host computer.

Interrupt monitoring is enabled upon receiving an Enable /INT Monitor command

from the host computer. Interrupt monitoring causes the iPort/USB to monitor the

/INT signal level, and send a notification to the host computer when the /INT signal

changes state.

3 Hardware Configuration

3.1 Pull-up Resistors

C Bus systems are based on open-collector technology requiring pull-up devices

on each signal wire. These pull-up devices usually take the form of pull-up resistors

connected to bus power.

The I

C adapter includes a slide switch used to enable or disable internal +5VDC

C Bus 1.8K ohm pull-up resistors attached to the SCL, SDA, and /INT lines.

Every I

C Bus system must have at least one pull-up on the signal lines. Use this

switch to configure the pull-up resistors for your system.

3.2 Connecting to a 3.3 Volt Target System

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MCC MIIC-203 Guía de usuario Pagina 15