[SOLVED] How to power on Sim908 breakout?

[bluejade]

I bought sim908 breakout (https://www.open-electronics.org/localizer-with-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

 

[neddie]

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.

 

[bluejade]

Hi Neddie,

What do you mean by pin 1 high?

 

[neddie]

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.

 

[bluejade]

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