User's Manual

Smart Machine Smart Decision
SIM5320_Hardware Design_V1.01 2011-11-10
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UART_CTS 67 I H Pull-Up
UART_DTR 72 I H Pull-Up
UART_DCD 70 O H
UART_RI 69 O H
More pin information refers to chapter 2.2.
Table 8: Logic level
Parameter Min Max Unit
Logic low input 0 0.3*VDD_EXT V
Logic high input 0.7 *VDD_EXT VDD_EXT +0.3 V
Logic low output GND 0.2 V
Logic high output VDD_EXT -0.2 VDD_EXT V
Note: VDD_EXT (=2.6V) is e reference voltage in module internal interface.
All pins of all serial ports have 8mA driver capacity.
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 20: 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.