User's Manual

Smart Machine Smart Decision
SIM5320A_Hardware Design_V1.01 2011-2-29
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Figure 22: 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 23: RI behaviour in FULL Modem
To comply with RS-232 protocol, the RS-232 level shifter chip should be used to connect SIM5320A 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: SIM5320A supports the communication rate: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200,
230400, 460800, 921600, 3200000, 3686400, 4000000bps. Default rate is 115200bps.
3.4 Audio Interfaces
SIM5320A provides two analog signal outputs and one analog input. MIC1P/N is used as microphone,
EAR1P/N and SPK_P/N are used as audio output. Regarding audio parameters configuration, please refer
to the ATC manual.