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How to start SIM900D without PWRKEY in modem

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yousafzai82

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Hi all,

I want to design GSM modem using SIM900D. I don't want to use PWRKEY to start the modem coz i am not using IC and i dont want to use button as well.

Is there any other way to start the modem when external 12v is supplied????????
 

cool.man

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I don't want to use PWRKEY to start the modem coz i am not using IC
Which IC you are talking about?

As in the design manual of sim900D,there describe two methods
By using a switch
By using a transistor

if you are using microcontoller then you can use transistor logic, by this way you can control the ON/OFF state by microcontroller.

Should i ground PWRKEY pin ground permanently???????
you can not permanently ground the pin because PWRKEY normally is pulled up for working state.

Best Regards
 

yousafzai82

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I used MCU to start the modem..Now i am facing another problem..When i connect it through hyperterminal it works fine on all flow controls.i.e None,Hardware, and Xon/Xoff... But when i connect it with some software like bulk SMS software...it is not detecting the modem...I am using all pins except RI dedicated to serial port in the module..

Sometimes it is changing the baud rate automatically from 8N1 to 7E1...

Can anyone suggest what may be the problem...
 

renderlove

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Check the coding thoroughly for the baud rate mentioned anywhere, if it changes then change the baud rate in hyper terminal once the code stops appearing in hyper terminal, after disconnecting.
 

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