The first thing you need to establish is the power source.
For simple AT command testing you can use the +5v from the Uno, but if you are making 'calls' then the shield needs up to 2Amps peak for a short time, so you need to fit a separate 5v supply the the shields power socket and move the power select switch to External (up).
The Serial select jumpers should be used as shown in the picture in that link.
To stop and start the board you use the Power Key, press and hold for a second or two, but you can also turn it on and off from your software if you solder across the JP pads, again shown in that link.
There are lots of AT Command testers on the web and some code examples, though as I initally found, not all work as intended.
I'm using an external power supply, so the SIM900 is running and now the NetLight is flashing every three seconds. I think that's the sign that the GSM is connected, right?
I have pins 7 and 8 connected to pins 7 and 8 of the arduino. Is that correct?
How can I send a test sms? I don't really understand the AT tester you've posted.
The AT command tester is just a basic way to test out the Sim900 module to make sure you have proper communicating between the two.
If you send out the AT you should get back "ok" which means you have a connected link, it does not need a Sim Card to do those basic tests.
Pin7 and 8 are as you say. You have plugged the whole shield onto the Uno ?
Will post a test sketch for you in the morning if no one else does in the meantime.
Here is a test routine for your board, have just run it ok on my shield. ( not my coding )
Power you board on and then run the code, then open the Serial Monitor and you should get the instructions for the various options, see if you can get the expected responses to prove it can communicate with the sim900.
If you have JP soldered across, the program works fine.
I uploaded it to my arduino and it seems to be able to connect with the SIM900.
I tried to send an sms using the command "sms +XXXXXXXXXXXX YYYYYYYYYY". However it always cuts off the last digit of my phone number. Please check out the attached screenshot.
Ich added another "X" wherever the phone number appeared in the code because I thought that might be the problem but I get the same result? Do I need to change anything else?
Did you type in IMEI and get a string of number back, that confirms you are talking to the chip.
Yes, the way to enter the moblie number is not clear, I did send a SMS out with it earlier this morning.
Give me a few minutes and will check what I entered.
Ok, still could not get it to accept the number via the Serial monitor screen.
If you edit that code, first turn on the Line numbers ( Flie, preferences ) then look at lines 12 and 111 they show String call sms and space for a 12 digit number - insert your number there, Country code and number.
Im in the Uk and the country code and number both start with Zero eg 044 , so we have to drop those leading zeros.
Upload the code and just type SMS and it sends a blank text out ok.
If you type SMS followed by 12 spaces you can then key in some actual text , then press Send.
I guess our shields have different LEDs. I don't have a green LED but a red one on one side that stays on constantly and two red one on the other side, one of which flashes at about once a second, the other is on permanently. That is without the SIM card. If I insert the SIM card it flashes once every three second.
I can only upload code if the SIM900 isn't powered up. If it's powered up I get a bunch of error messages. So I've turned it off, uploaded the code, the turned it on.
The serial monitor now shows me the same commands "SIM900 board is ready...".
However if I type in "imei" nothing happens.
This thing is really hard to get going? Other than anything else I've tried with arduino so far.
Well have just used the code I posted for you, and it uploads and works fine on my board, with the sim900 shield powered on or off.
After the sim900 board ready, does it also print the line ' type help to see available commands ' ?
The leds sound right, just that two of mine are green, better to refer to them as the power, net and status leds instead of colour.
All I can suggest is you double check the connections again.
No power plugged in to the sim shield.
The power select switch in the position shown in the pic below.
The comms port select jumpers, fitted as shown.
If that still does not work, place the power select switch in the other position (up) and connect your 5v power source to the jack and then power on.
Hii, i've the same problem than Badalou. i don't know if the wiring is correct or not. The red power light is constantly on, the red status light too and the red netlight flashes every 3s.
Can someone help me plz??????
