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Topic: SIM900A GSM/GPRS Module, Frequencies: 900/1800MHz (Read 2433 times) previous topic - next topic


I have a few questions to unlock this module's frequency bands for use in the USA.  First off, I understand this module needs to be flashed with SIM900 firmware.  The instructions I've found on flashing are very confusing.  I understand there needs to be a TTL Level (USB /Serial) communication between the computer and module.  I'm using a Bluetooth USB dongle in the laptop and a Sparkfun Bluetooth Silver Mate connected to the module for flashing.

First I need to know which port (com#) to connect to using my Sparkfun Bluetooth Silver Mate Antenna.  I know this is specific to each computer and protocols available, but what is the easiest way to get the dongle and Bluetooth Silver Mate paired up?

Can I use AT commands between  (Arduino's serial monitor, BT dongle in PC) and (Bluetooth Antenna, GSM module) only?

Once I figure out which COM my Bluetooth Silver Mate and GSM module is on, then I can use the SIM900 Series Download Tool Develop 1.9.exe software to update my SIM900 firmware.  HOWEVER, I'm stuck on step 1 and 3.

Step 1: Power up your SIM900A module to respond to AT commands in auto-baud mode (AT+IPR=0). It means you must wire powerlines, do power-on sequence with PWRKEY etc.

PWRKEY is a pin on the SIM900A.  What exactly am I suppose to do here?  This is where I'm stuck.  Do I need a sketch running to use AT commands?  What does it exactly mean to wire powerlines and do a power-on sequence with PWRKEY etc??

Step 3: Short NRESET (pin 16) to GND for a moment. Right after it reboots flashing tool will start pushing data.

Do I really need to temporarily solder on wire to the NRESET pin of the SIM900A for shorting to GND?  Once I ground NRESET pin do I leave it grounded until the new firmware is installed or is this just a quick GND pin and release?

From what I understand if I had an Arduino board with the FT232 chip or a FT232 USB breakout board then I wouldn't need to directly access pins on the SIM900A.  Is that true?  There is mention of an "Arduino approach".

EBAY SIM900A GSM device

Page 13 SIM900A pinout



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