User's Manual

Smart Machine Smart Decision
SIM5320AL_User Manual_V1.01 2014-08-20
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3.3.2 Application Guide
If UART port is used in Null Modem, the pin “RI” can be used as an interrupt signal to HOST. Normally it
will keep high logic level until certain condition such as receiving SMS, voice call (CSD, video) or URC
reporting, then “RI” will change to low logic level to inform the master (client PC). It will stay low until
the master clears the interrupt event with AT command.
Figure 19: 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 20: RI behaviour in FULL Modem
To comply with RS-232 protocol, the RS-232 level shifter chip should be used to connect SIM5320AL to
the RS-232-C interface. In this connection, the TTL level and RS-232 level are converted mutually.
SIMCom recommends that user uses the SP3238ECA chip with a full modem. For more information
please refers to the RS-232 chip datasheet.
Note: SIM5320AL supports the communication rate: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200,
230400, 460800, 921600, 3200000, 3686400, 4000000bps. Default rate is 115200bps.