MTX-DIN Family
www.mtxm2m.com
2015/10 v2.3
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MTX M2M® by MATRIX ELECTRONICA S.L.U
4.2.5
I2C bus
I2C 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 MTX-DIN modem acts as a single master device, e.g. the clock I2CCLK is driven by the modem.
I2CDAT is a bi-directional line.
Each device connected to the bus’s software is identified by a unique 7-bit address. Simple
master/slave relationships exist at all times: the modem operates as master-transmitter or as
master-receiver. The customer application transmits or receives data only at the modem’s request.
I2C lines are located at pins 31 and 32 of the terminal block
1.
I2C lines are Open Drain. Internal 10kOhm pull-up resistors are mounted, so there is no need
to fit them by the host application.
2.
According to the I2C Bus Specification Version 2.1 for the fast mode a rise time of max. 300ns
is permitted.
3.
The value of the pull-up depends on the capacitive load of the whole system (I2C Slave +
lines). The maximum sink current of I2CDAT and I2CCLK is 4mA.
4.
If lines are unused, keep pins open
Use the AT^SSPI command or Java class to configure and activate the I2C bus.
The picture below shows I2C interface is powered from an internal VEXT supply line so the I2C
interface will be properly shut down when the modem enters Power-down mode.
Signal
Direction Description
I2CCLK
Output
I2C bus clock signal
1234
I2CDAT
I/O
I2C data bus
1234
