User's Manual

Smart Machine Smart Decision
SIM5320_Hardware Design_V1.01 2011-11-10
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Figure 17: Power off timing sequence
Table 6: Power off timing
Parameter Description Time value Unit
Toff The time pulling POWER_ON down to power off 0.5< Toff<5 s
TpD- The time to indicate disconnecting from the network >7 s
Tpw- The time to indicate the module power off completely >7.5 s
Tuart_off The time to disable UART >6 s
Tusb_off The time to disable USB >7.5 s
User can also use the AT command “AT +C POF ” to power down the module. After that, the AT commands
cannot be executed any longer. The module enters the POWER DOWN mode, only the RTC is still active.
For details, refer to Document [1].
3.3 UART Interface
SIM5320AD provides a UART (universal
asynchronous serial transmission) port. It consists of a flexible
7-wire serial interface. The module is as the DCE (Data Communication Equipment) and the client PC is
as the DTE (Data Terminal Equipment). AT commands are entered and serial communication is performed
through UART interface. The application circuit is in the following figures.