Powering GSM

how can i power on the GSM module without pressing the button? what codes should i use? i am using SIM900D and arduino mega 2560.. Tnx!

What button?

And don’t cross post.


The power button of GSM module. I wanted to put it in a code instead of pressing it manually.

What button? What module?

For all I know the GSM900D is a component you solder onto a PCB, it doesn't have a button. If it's a shield or something provide a link, I shouldn't have to use Google on your behalf.


Here is the link sir, http://www.e-gizmo.com/KIT/gsm%20shield.html..

Thank you so much sir, i appreciate that you are responding to my post :slight_smile: :slight_smile: :slight_smile:

According to the schematic there is a transistor across the power switch and the base of that transistor goes to pin1 of a 2x6 header (JP6). So in theory you could apply a voltage from a spare Arduino pin (through a resistor) to that base.

Trouble is from what I can see in the photo and other diagrams there is no JP6.

Do you have the board in front of you? If so can you see this header or at least the holes for it?

EDIT: There should be a power down command, look up AT+CPOWD


What is the purpose of the Vin pin?

That would be connected to the Arduino VIN, it will have whatever power you are using for the Arduino.


Sir i saw this link: http://tronixstuff.com/2013/09/18/tutorial-arduino-sim900-gsm-modules/

i wanted a code like this:

void SIM900power()
// software equivalent of pressing the GSM shield "power" button
  digitalWrite(9, HIGH);
  digitalWrite(9, LOW);

but i don't know where the digital pin 9 is connected.

That's a totally different shield so the code is of no help.

I asked some questions before, any chance of an answer?


I cant find the JP6. But the board have a pad that is labeled PWR. Is that it?

It doesn't look like it, according the the documentation that might be a "Power indicator".

There's no way for me to tell without a proper schematic, the schematic in their manual appears to be just plain wrong, it even has a SIM340D module but the shield is supposed to have a SIM900D.

Either they are incompetent or they are doing what I see a lot of people doing who profess to be "open", they publish a bogus schematic.

So I don't think I can help any more, I suggest you ask the people you bought it from, or try the AT command I mentioned.


Sir the pwr pad is connected to the pwrkey of the SIM900D board, is it right to supply pwr (which also makes you are like supplying pwrkey of the SIM900D) pad using digital pin from arduino?

the pwr pad is connected to the pwrkey of the SIM900D board

How do you know that? Do you have proper schematics?

If that's the case you should not directly connect an Arduino pin because the SIM runs at about 4v. You have to pull PWRKEY to GND for 100mS (IIRC) and release it to floating. The normal way to do that is to use a transistor to pull PWRKEY low.


sir i already saw the pad where the power on is connected, can i directly connect a digital pin from arduino to power it up?

That doesn't answer my question, so I have to say no you should not connect Arduino pin to it.


is that the pin where i should connect my digital pin from arduino?

Thank you for the help...

That is from the manual and I've already said the schematic is incorrect. It looks like if you solder across that bridge between the A5 socket and the power button you can then use the A5 pin to control the power and you don't need to run any wires. BUT that's not how the schematic is.

I will not comment any more without proper documentation, I don't do things because they look like they should be right. Find correct documentation, or try the AT command or connect an Arduino pin to that point and see what happens, it's your board.


Sorry sir. I have my module right now and i confirmed it already, it is correct. i was confused also about their schematics. but the picture i posted was right. Can you help me what to do next? Please sir, i need your help.

Alright, try this but it’s on your own head.

Connect a resistor (around 1k) between the 5v socket and the half of the solder bridge that’s nearest the power switch, as shown in the attached pic.

With luck this will turn Q3 on which in turn will shut down the module after 100mS.

If that works maybe we can figure out a more permanent solution.