I am working on project in which i am trying to send message with the help of SIM900 gsm modem.

i followed procedure as per mentioned link and working fine.

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when i trying with standalone arduino its not working any how.

let me guide, am i missing something?

my standalone arduino tested with blink led and working fine. see attached image of my standalone arduino.

Anyone ?

no reply?

Where is the pull-up resistor on the reset pin?

its not working

Sorry, that is not a valid way of describing an issue. Try again.


i have connected resistor at back side,

not working means,

i am not getting any message/output by stand alone atduino.

other examples are working perfectly.

How are you powering the GSM modem ?

by 12v adopter.

GSM modem working perfectly with arduino board.

by 12v adApter.

GSM modem working perfectly with arduino board.

How are your programming your Stand-alone Arduino ?

From here ..

i made on pcb, please have look on arduino image(in my first post)

If You can program the Arduino just fine, i cannot figure out why the serial connection for the Modem isn't working, sorry ...


grounds connected?

Yes Dear,

Ground connected