Specifications

Cinterion
®
ALAS66A Hardware Interface Overview
2.1 Application Interface
33
 ALAS66A_HIO_v01.000a 2019-02-26
Confidential / Released
Page 20 of 51
2.1.4 I
2
C Interface
ALAS66A provides two I
2
C interfaces. I
2
C is a serial, 8-bit oriented data transfer bus for bit rates
up to 400kbps in Fast mode. It consists of two lines, the serial data line I2CDAT and the serial
clock line I2CCLK. The module acts as a single master device, e.g. the clock I2CCLK is driven
by the module. I2CDAT is a bi-directional line. Each device connected to the bus is software
addressable by a unique 7-bit address, and simple master/slave relationships exist at all times.
The module operates as master-transmitter or as master-receiver. The customer application
transmits or receives data only on request of the module.
The applications I
2
C interface can be powered via the VEXT line of ALAS66A. If connected to
the VEXT line, the I
2
C interface will properly shut down when the module enters the Power
Down mode.
In the application I2CDATx and I2CCLKx lines need to be connected to a positive supply volt-
age (e.g., VEXT) via a pull-up resistor.
Figure 5: I
2
C interface connected to VEXT
Note: Good care should be taken when creating the PCB layout of the host application: The
traces of I2CCLK and I2CDAT should be equal in length and as short as possible.
I2CCLK
I2CDAT
GND
I2CCLK
I2CDAT
GND
Module Application
VEXT
R pull up R pull up