User's Manual

Smart Machine Smart Decision
SIM5360A_User_Manual_V1.03 2014-07-03
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Figure 18: RI behaviour in NULL Modem
If Full Modem is used to establish communication between devices, the pin “RI” is another operation
status. Initially it keeps high, when a voice call or CSD call comes, the pin “RI” will change to low for
about 5900ms, then it will return to high level for 100ms. It will repeat this procedure until this call is
answered or hung up.
Figure 19: RI behaviour in FULL Modem
The SIM5360A UART is 1.8V interface. A level shifter should be used if user’s application is equipped
with a 3.3V UART interface. The level shifter TXB0108RGYR provided by Texas Instruments is
recommended. The reference design of the TXB0108RGYR is in the following figures.