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

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muwasif

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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
 

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

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
 

I did but got No response and it is obvious.
 

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....
 
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
 

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.
 

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
 
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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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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.
 

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
 

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....
 
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    sherazi

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

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???
 

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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