LED is blinking very fast due to the unavailability of network / signal. Check the following.
does your sim working when inserted to a mobile phone.
are you inserting the sim correctly to the sim tray of the module.
also did you connect the antenna provided with the module (short antenna)
Power supply by 5V, can be powered by USB, for long term use it is better to still use 1A current power source.
Today I have tested my module. My setup is as follows,
arduino mega 2560
sim900a module
FTDI232 serial to usb module.
12V 2A power supply.
I have connected the 12V 2A power supply to arduino mega and then take 5V and gnd lines to sim900a modem using power connector on gsm module.(red and black wire). then connect 5VT and 5VR with GND of sim900a module to FTDI232 module.
tested and working.... here i used mega as a power supply to initial test.... happy its working ... but remember you have to supply power separately to sim900a module and connect ground lines together.
LED is blinking very fast due to the unavailability of network / signal. Check the following.
does your sim working when inserted to a mobile phone.
Yes, SIM is working when is inserted to mobile phone.
[/quote]2. are you inserting the sim correctly to the sim tray of the module.[/quote]
Yes
[/quote]3. also did you connect the antenna provided with the module (short antenna)[/quote]
yes
I am giving power supply of 5v 2A using adapter to SIM900A still led is blinking fast.