Cinterion
®
Java Terminals Hardware Interface Overview
3.6 GPIO Interface
39
EHSxT_BGS5T_HIO_v03
2016-05-26
Confidential / Released
Page 29 of 50
3.6.3
I
2
C Interface
Two lines of the Java Terminals‘ GPIO connector are I
2
C lines. 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 Java Terminals‘ internal Java module
act as a single master device, e.g. the clock I2CCLK is driven by the Java 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 Java module operates
as master-transmitter or as master-receiver. An external application transmits or receives data
only on request of the module.
To configure and activate the I2C bus use the AT^SSPI command. Detailed information on the
AT^SSPI command as well explanations on the protocol and syntax required for data transmis-
sion can be found in
With the external application, I2CDAT and I2CCLK lines need to be connected to a positive
supply voltage via a pull-up resistor.
Note: Good care should be taken when connecting the I2C lines to the external application: The
wires of I2CCLK and I2CDAT should be equal in length and as short as possible.
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