Can't get Arduino UNO with Adafruit FONA 800 Shield to work

Sketch builder does not specifically support FONA 800 but it is in the list of supported products. Anyway, I selected the SimCom SIM800 and get:

[13310] Modem init…
[23539] Cannot init

I’m using a hologram sim card.


That means the modem is simply “invisible” to Arduino. Bad serial connection, wrong serial port settings?? Error in code? Who knows? Too little information provided.

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At a bit of a loss as to what other info I might provide I remembered something way back about incorrect pins for the software serial so, in desperation swapped them:

SoftwareSerial SerialAT(3, 2);

and got this, with about a 10 min gap after “[23989] Connecting to hologram …”

[13116] Modem init…
[16461] Connecting to network…
[23989] Network: Rogers Wh�eless
[23989] Connecting to hologram …
[201782] Connect GPRS failed
Initializing modem…
___ __ __
/ _ )/ /_ _____ / /__
/ _ / / // / _ / '/
//_, /////_
__/ v0.6.1 on Arduino Uno

[16501] Modem init…
[23846] SIM is missing
Initializing modem…

Perhaps SoftwareSerial is set incorrectly (speed?). But because of your “TOP SECRET” code, that is all I can help you.


This bit of code is from the Adafruit Fona 800 test example:

#define FONA_RX 2
#define FONA_TX 3
SoftwareSerial fonaSS = SoftwareSerial(FONA_TX, FONA_RX);

Now, I did generate the example for the SimCOM SIM800 (the FONA 800 is not in the list) and the generated code would be correct. However the FONA is quite popular and a comment in the generated code might save some confusion.

Thanks very much for the support and if I can’t get this working today I’ll buy a SIM800. Cheers.

Perhaps this should be your start point:

Generated code:


Changed to 9600 and connects fine. A comments please.

So You wasted some significant amount of time just because you were keeping it secret… Up until now. That is my comment.

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My apologies for confusion.

The code generated by the example builder for the Arduino and SimCOM SIM800 contains:

SoftwareSerial SerialAT(2, 3); // RX, TX

To work with the Adafruit FONA 800 these lines need to be changed to:

SoftwareSerial SerialAT(3, 2); // RX, TX

It would help if the code generated included a comment with these changes for those trying to get the FONA working.


FYI SoftSerial on Atmega (Arduino) works quite stable up to about 33600 bps