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    SIM900D Interfacing with hyper terminal.........

    Hi, I am using Simcom SIM900D. I just want to interface this module with PC hyper terminal. I have followed all the precautions and design mention in hardware design. When I power up the module it send "ΔΔΔΔ" on hyper terminal @ 9600 baud rate and send nothing on different baud. (It is mentioned in the manual that it should not send any data when using in auto baud mode). After that it stops responding. Any suggestion to solve this issue??
    Thanks in advance
    wasif

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    Re: SIM900D Interfacing with hyper terminal.........

    send command AT+IPR? and see the response or do AT&F and re-power on the modem...

    its clear baud mismatch problem.
    " It is so simple to be happy,
    but it is so difficult to be simple"


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    Re: SIM900D Interfacing with hyper terminal.........

    Module is not responding on AT command How can I send these commands ??



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    Re: SIM900D Interfacing with hyper terminal.........

    there will be ignition switch other than power ON switch... check if it is ON...

    check if the cable is working properly....
    " It is so simple to be happy,
    but it is so difficult to be simple"



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    Re: SIM900D Interfacing with hyper terminal.........

    Quote Originally Posted by ckshivaram View Post
    there will be ignition switch other than power ON switch... check if it is ON...
    YES there is a PWRKEY and I ignited... All the power up conditions verified. Module is powered up properly.

    check if the cable is working properly....
    I have checked. Cable is working properly



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    Re: SIM900D Interfacing with hyper terminal.........

    could you swap tx and rx on one side of cable and try...........
    " It is so simple to be happy,
    but it is so difficult to be simple"



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    Re: SIM900D Interfacing with hyper terminal.........

    I did but got No response and it is obvious.



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    Re: SIM900D Interfacing with hyper terminal.........

    modem may be receiving commands from terminal but not replying means modem in unable to transmit, but coould receive, so change max 232 in modem and check with both configuration of tx and rx in cable....
    " It is so simple to be happy,
    but it is so difficult to be simple"


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    Re: SIM900D Interfacing with hyper terminal.........

    Quote Originally Posted by ckshivaram View Post
    modem may be receiving commands from terminal but not replying means modem in unable to transmit, but coould receive, so change max 232 in modem and check with both configuration of tx and rx in cable....
    Let me check I'll get back to you soon. Thanks



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    Re: SIM900D Interfacing with hyper terminal.........

    Problem solved
    I am still finding the key problem but what I doubt it was <\r> I used every time when sending 'A' for baud rate sync. I'll update if I got any other reason
    Thank you for your timely response.



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    Re: SIM900D Interfacing with hyper terminal.........

    u should send AT\r
    are u sending \r at the end of the command.

    dont use sms or short hand typing skills in this forum... type the complete words by spending few more seconds. this is the last warning and further posts and thread of yours will be deleted without informing you if continued
    Last edited by ckshivaram; 22nd May 2011 at 10:36. Reason: sms typing used



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    Re: SIM900D Interfacing with hyper terminal.........

    Quote Originally Posted by muwasif View Post
    Problem solved
    I am still finding the key problem but what I doubt it was <\r> I used every time when sending 'A' for baud rate sync. I'll update if I got any other reason
    Thank you for your timely response.
    hi muwasif

    i am also working on sim900 interfacing, for some reason i am not getting success with it. can you please share your schematic? or if possible please take a look at my schematic. it will help me to troubleshoot the problem.

    i have prepared two printed circuit boards with the same schematic, when using the first one i get repeated default (RDY) response from the module on powering up, even if i don't send anything, 50-60 times a second.

    using the second board the netlight remain on continuously, i haven't connected second board with PC, so i don't know its response.

    I don't know what i am doing wrong. I would really appreciate your help

    thanks



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    Re: SIM900D Interfacing with hyper terminal.........

    Quote Originally Posted by devil6600 View Post
    i get repeated default (RDY) response from the module on powering up, even if i don't send anything, 50-60 times a second.
    It indicates that your module is restarting continuously. Make sure that there is no repeating pulse at pin 5 of conn1.



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    Re: SIM900D Interfacing with hyper terminal.........

    What is the power supply you are using voltage and current????
    " It is so simple to be happy,
    but it is so difficult to be simple"



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    Re: SIM900D Interfacing with hyper terminal.........

    i am using lm317 for power supply...
    a quick question... i was checking continuity between antenna pad and ground pad on a new module and i found both of them short(antenna & ground).. is it normal with sim900? can you please verify this?

    thanks



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    Re: SIM900D Interfacing with hyper terminal.........

    Yes antenna has very low resistance as the antenna pad is connected to a inductor internally. so there will no hardly any resistance .. it common for any device.... i dont understan when you tell lm317 for your power supply.. thats not what i asked .. i asked adaptor or power supply rating....
    " It is so simple to be happy,
    but it is so difficult to be simple"


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    Re: SIM900D Interfacing with hyper terminal.........

    thanks ckshivaram for the antenna and ground clarification
    i am using 12volt 5amp ac adapter connected to lm317...



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    Re: SIM900D Interfacing with hyper terminal.........

    5A seems to be too much as the data sheet of LM317 specifies it can take upto 1.5A max. use 1A power supply and try.... Is there any protection to your modem. or any additional circuits???
    " It is so simple to be happy,
    but it is so difficult to be simple"



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    Re: SIM900D Interfacing with hyper terminal.........

    i bought adapter and power supply kit (lm317 kit) from a local vendor, this is the same power supply i have used with wavecom modules. it has few resistors, capacitors and lm317 ic. the adapter has a label of 12v 5amp

    i got sim900 partially working.. but now it gets switched off automatically after sometime (just after network registration) without any warning/message, i am sure now the issue is power supply only, can you please advice me which power supply to use with sim900? any schematic would be helpful

    thanks



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    Re: SIM900D Interfacing with hyper terminal.........

    Quote Originally Posted by devil6600 View Post
    i am using lm317 for power supply...
    LM317 is not enough to power SIM900 as the module takes 2amp on transmit buffer. you should use LT1085 or equivalent..



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