User Manual

Cinterion
®
ELS31-V/ELS51-V Hardware Interface Overview
2.1 Application Interface
17
ELS31-V_ELS51-V_HIO_v00.502 2015-12-07
Confidential / Preliminary
Page 12 of 35
2.1.6 I
2
C Interface
I
2
C is a serial, 8-bit oriented data transfer bus for bit rates up to 400kbps in Fast mode. It con-
sists 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-direc-
tional line. Each device connected to the bus is software addressable by a unique 7-bit ad-
dress, 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 I
2
C interface can be powered via the V180 line of ELS31-V / ELS51-V. If connected to the
V180 line, the I
2
C interface will properly shut down when the module enters the Power Down
mode.
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.