Sim 300 GSM modem with 89C51 Microcontroller

[paramathma]

hi
i m working with Sim 300s v7.03 modem interfacing with 89C51... when i work seperately they r working well... i can see the results too... but wen i interface modem does not respond... wen i give the command from microcontroller modem led goes off for few seconds then it glows... can u help me to interface it properly... thank u...

 

[umang_242087]

check the connection....Txd of u.controller is connected to RxD of gsm and Rxd of controller is connected to txd of GSM...also PIN 5 of both are commone????

 

[@bc]

hi i m doing my project on intruder alarm with gsm i also using the same gsm module and microcontroller but i m very bad in coding and also i m working with gsm module for the first time so can u plz mail me the schematics and the code i really need it urgently

with regards
@bc
andleeb.irum@yahoo.com

 

[CHIMU]

HEY , U NEED TO CONNECT RX OF MICROCONTROLLER TO THE 2ND PIN OF DB9 OF MODEM AND TX TO THE 3RD PIN OF MODEM.

i.e if u r using

MICRO CONTROLLER -> max232 -> DB9 connector -> "RS232 Cable" -> modem

then u must have cross connection at "quoted" rs 232 cable i.e. 2 and 3 pins must be swapped between 2 ends of RS232 cable ,
check it out it will work, I suffered a lot due to same problem but it was d solution, do it and move ahead coz programming part is real challenge w8ng for u

if u r done with it
plz help me in progrm .....