MCC MIIC-203 Guia do Utilizador descarregar pdf (Página 14)

/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

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

If you are connecting the I

C adapter to a 3.3 volt target system, you should follow

these steps BEFORE applying power:

• Shut off the I

C adapter’s internal pull-ups (See Pull-up Resistor section). Use

external pull-ups to the target system’s 3.3V power. These pull-ups may already

be present in the target system.

• Disconnect the I

C connector +5V wire from the target system. The I

C adapter

will be powered from its own +5V power supply, and the target system will be

The I

C adapter is a 5-volt device. Any signal above 3.3V on the SCL and SDA

lines is high enough for the adapter to see a Logical 1.

3.3 Connecting to an SMBus Target System

If you are connecting the I

C adapter to a SMBus target system, you should follow

these steps BEFORE applying power:

• Shut off the I

C adapter’s internal pull-ups (See Pull-up Resistor section).

• Use external SMBus rated (approx. 15k ohm) pull-up resistors. These pull-ups

may already be present in the target system.

• Visit the I

C .vs. SMBus FAQ page (www.mcc-us.com/I2CSMBusFAQ.htm).

• See the SMBus Specification for additional details.

Special Note for SMBus Users: MCC’s I

C adapters are designed to be I

C Bus

compatible, not SMBus compatible. Some features of the SMBus protocol not

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 70 71

Sem comentários

MCC MIIC-203 Guia do Utilizador Página 14