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  1. #1
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    How to power on Sim908 breakout?

    I bought sim908 breakout (http://www.open-electronics.org/loca...sim908-module/) but without the breakout board which has microcontroller. I have connected VCC (pin 17, 19), GND (pin 18, 20), TXD (pin 12) and RXD (pin 14). The power (ON/OFF) pin is 1 but how to invoke the module to turn on?
    Do I have to connect it to positive terminal or negative terminal?

    I want to test the module whether it is okay or not using AT command (AT ---> response: OK) using serial communication.

    Thanks

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  2. #2
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    Re: How to power on Sim908 breakout?

    I have only used the SIM900 module , but I assume they are similar. You need to turn on the module by holding the on button for about 500mS. In your case , pin 1 high.
    I think the unit defaults to autoboard , you should see some characters coming out of the serial port on power up.
    Sending "AT" to the serial port sets up the autoboard. You may have to do this a few times , until you get a reply of "OK"
    Cheers
    Neddie.



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  3. #3
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    Re: How to power on Sim908 breakout?

    Hi Neddie,

    What do you mean by pin 1 high?



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  4. #4
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    Re: How to power on Sim908 breakout?

    Look at the schematic from the link you poster. The power pin for the sim908 is pin3. It's driven by a transistor(open collector) , which you have to drive high to turn on.
    The transistor is going to pin1.



  5. #5
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    Re: How to power on Sim908 breakout?

    Thanks Neddie. The pin 1 just need to be supplied with power only.



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