Gpio Selection; Status And Netlight - SimCom SIM900 Reference Design Manual

SIM900 Reference Design Guide Notes

2.3 GPIO selection

2.3.1 STATUS and NETLIGHT

STATUS pin can be used to monitor the module state during the power on/off process. After
power up, AT command will response till the STATUS change high, and it will change low after
the module log off from the base station in a power down procedure. It can be connected to a
GPIO of the MCU.
NETLIGHT is a net status indicator. It can drive a transistor to control a LED which will blink
slowly or quickly according to different states. Please note that it can't drive a LED directly.
Both STATUS and NETLIGHT is dedicated in SIM900, they can not be used as a GPIO for the
customer.
SIM900_AN_Reference Design Guide_V1.01
Figure 6: Serial Port Connection
DBG_TXD
DBG_TXD
DBG_RXD DBG_RXD
GND GND
Figure 7: Debug Port Connection
6
TXD
RXD
GND
01.27.2010