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Topic: Need some help working with a SM5100b shield (Read 953 times) previous topic - next topic


Mar 13, 2012, 07:49 pm Last Edit: Mar 13, 2012, 07:54 pm by rturk3 Reason: 1
I am trying to connect a SM5100b cellular shield from sparkfun with my Mega 2560.

I have followed John Boxall's tutorial. Here is my set-up and issues, any advice is greatly appreciated:

Shield D2 to Mega 19
Shield D3 to Mega 18.

Arduino and Shield powered via a 5V 2A rail.

When I load the pass-through sketch I get:

Starting SM5100b Communication...
Then a bunch of small boxes (empty characters)

I tried both 9600 and 115200 for the Serial1.begin rate.

Can anyone think of something else I can do, or notice anything funny in my setup? Any way to test if the module is bad? I tested each header pin on the shield and they're all good.


Did you get the issue resolved? I'm at the same point today.



It sounds like your sm5100b is configured for 115200 baud which SoftwareSerial doesnt handle.  I had the same issue.  To resolve you need to load a blank sketch onto your arduino (define empty setup() and loop() functions).  And run a jumper from pin 2-3 and 1-4.  then use a terminal application (hyper terminal on win/ screen on mac) and connect to the usb serial device at 115200 baud.

Then send the following command:


and restart, then you can talk to it at 9600 baud



I'm getting problems ~ similar to yours.
Please take a look


Thanks on advance
Pedro Ferrer

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