SIM900D Hardware Design
3.15 Network Status Indication
The NETLIGHT can be used to drive a network status indication LED lamp. The working state of this pin is
listed in following table:
Table20: Working state of the NETLIGHT
State
SIM900D function
Off
SIM900D is not running
64ms On/ 800ms Off
SIM900D does not find the network
64ms On/ 3000ms Off
SIM900D find the network
64ms On/ 300ms Off
GPRS communication
Provide a reference circuit for user, shown as following figure:
300R
4.7K
47K
MODULE
NETLIGHT
VBAT
Figure28: Reference circuit of NETLIGHT
3.16 General Purpose Input Output (GPIO)
SIM900D provides a limited number of General Purpose Input/Output signal pin. The output and input voltage
level of the GPIO can be set by AT command.
For more details, please refer to
document [1]
SIM900D_HD_V1.02
09.04.2010
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