I recently bought a quad-band SIM900 mini V4.0 GSM board (http://www.ebay.com/itm/SIM900-MINI-V4-0-WirelessData-Transmission-Module-with-Antenna-Cable-for-Arduino-/281493144780). My problem is quite poor documentation about it. I don't know how to properly supply it as well as how to communicate with it using serial communication (not RS232). Is there any of you out there having experience with this board and willing to give me some advice on the topic?

Thank you in advance.



  • \$\begingroup\$ Word to the wise: consult documentation/datasheet before buying. The Wun Hung Lo guys can sell for the prices they sell at because they cut some corners, support/documentation often being among them. \$\endgroup\$ – Fizz Oct 6 '15 at 8:12
  • \$\begingroup\$ Real true, buddy! \$\endgroup\$ – bojankoce Oct 6 '15 at 8:18

Dude, The TTL port of the Sim900 mini v4 shield works with 2,8v. So if you want to connect your arduino Uno/Mega by TTL, you must buy a 3,3v to 5,0v converter.

The best way (I did and works perfectly) is to use a RS232 to TLL (max232) and use the RS232 shield port.

I expend many hours trying to use this GSM shield and I got good results using RS232 port (GSM shield - PC) and (GSM shield - Arduino Mega) using a RS232 to TTL converter.

  • \$\begingroup\$ And how do you supply the board? With how many volts, amperes? \$\endgroup\$ – bojankoce Jul 14 '15 at 8:52

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