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Member Since: March 5, 2007

Country: France

  • Hi Mike, Thank you for your answer. I will take a closer look on these antennas.

    I use the command you tell me ( and that was of course in the extended commands datasheet !! ), and i notice something about this command : - sim must be inserted, otherwise command returns “ERROR” - sim must be “pined” with the pin code, otherwise returns “ERROR”…

    After that, i would be able to change the baudrate to 19200 ( for users that use Atmega328 (arduino mini pro ), 115200 baud rate returns wrong characters, so that why i have to decrease baudrate of the modem ).

    After changing baudrate, i got something strange ( but i pass over this ). The first characters of the modem (

    SystemInit +ADSYS: BK=0x1,0x11, RV=0x1, Fail=0x0 +ADSYS: FLASH VERIFY OK ) become unreadable ( i was unable to find the correct baudrate to read them… ) The first valid characters i got were : “+CREG: 0”. I match them to begin the modem initialization and it works fine !!!!

    thank you again !!! Fred

  • Hi Mike, thank you for your comment. The antenna i use is a simple L form piece of metal that I got from a low cost wifi transmitter. Do you think it can even damage the gsm ? another question for you : the sparkfun antenna is quite large and I need a minimum space. In our GSM phone, we haven’t big antenna : is it possible to get smallest antenna chip or piece of metal ?

    I’m also working ( now for integration ) with an arduino mini pro 3.3v but software serial link at 115200 fails ( ftdi work fine however ). Is it possible to slow down UART0 of the GSM module ???

    Thank you for your help

  • so i can answer to my own question : yes, this module need an external antenna to work. I found an old wifi metal antenna with micro sma connector and now, +CSQ is 10,99. I successfully send my first SMS.

    Here is this simple script I use if someone is interested :

    +ADSYS: BK=0x1,0x11, RV=0x1, Fail=0x0 +ADSYS: FLASH VERIFY OK

    Ready at OK

    at+cpin? +CPIN: SIM PIN

    OK at+cpin=“xxxx” OK

    at+cpin? +CPIN: READY


    +CREG: 5,“1234”,“5678”

    OK at+cmgf=1 OK at+cmgs=“+33XXXXXXXXX”

    hello from my embedded gsm" +CMGS: 2


  • Hello, I just receive the GSM module and try to send some SMS. today, AT+CSQ command returns +CSQ: 0,99 => it seems that there is no network.

    question: should i connect an external antenna for gsm, or can the module communicates as it is ? Thanks for your help Fred

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