4. Pull DTR high, the module will exit from sleep mode actively, and furthermore enable the UART.
Thus the voice call, received data, or SMS can be processed through UART.After processing
finished pull it low again, to take the module back to sleep mode.
3.3.2 RING Signal Indicator
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Calling: Once a voice call is coming, UART output "RING" character strings and meanwhile the
RING pin outputs 30 ms low pulses at 5s period. After the call is answered, the high level restores.
Figure 3-14 RING indicator for incoming call
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SMS: Upon receipt of SMS, the module outputs one 35ms low pulse.
Figure 3-15 RING indicator for SMS
3.4 SIM Card Interface
Table 3-4 SIM Card Interface
Signal I/O Function Description Remarks
VSIM P SIM card power supply output 1.8V/3.0V
SIM_CLK DO SIM card clock output
SIM_RST DO SIM card reset output
SIM_DATA DI/O SIM card data IO Internal pull-up
M590 supports 3.0 V and 1.8 V SIM cards. VSIM supplies power for SIM card with 30mA.
SIM_DATA is internally pulled up by a resistor. External pull-up resistor is not needed.
SIM_CLK can work at several frequenciesat 3.25MHz typically.
5s
30 ms
30 ms
35 ms