Sim908 AT+CGPSPWR=1 ERROR

[bluejade]

Hi,

What are possible reasons that I got reply "ERROR" when I sent "AT+CGPSPWR=1"?

Thanks,
BlueJade

 

[jayanth.devarayanadurga]

Post your circuit. It is related to Power. Did you try sending the command to SIM908 from PC or from a microcontroller?

 

[bluejade]

schematic


actually I bought the sim908 breakout. I sent the command from PC. other than that, the terminal received "GPS ready" after the module was powered on.

 

[jayanth.devarayanadurga]

Is your antenna powered? Also do you have an antenna so that it connects to the network? Put your board or module near a window or outside. It will not pickup network if it is indoor.

 

[bluejade]

Do you mean that I cannot use GPS functionality or turn on GPS if the GSM network is not registered? Then it makes sense because it seems to not able to register to GSM network. Both the GSM and GPS have antenna.

 

[jayanth.devarayanadurga]

I think that is the problem.

 

[bluejade]

Somehow I do not think that failure of power on GPS has relationship with GSM network registration.

 

[bluejade]

After I changed baud rate to fix 9600, the following thing continuously happens.


The problems that still happen: cannot register to network and AT+CGPSPWR=1 got reply "ERROR" with description "operation not allowed".

The module is powered on by 3.7V battery. It is connected to computer using pl2303 USB. It is said that pl2303 USB has 5V.
I suspect this is the source of problem but I do not know how to solve it if it really is the source of problem.

 

[jayanth.devarayanadurga]

I think that is not a problem. If your module works at 3.7 V then the logic high will be around 2.5 V to 3.7 V. So it will also work with 5 V logic devices.

This might help you. https://www.edaboard.com/threads/250867/

 

[Batang]

The SIM908 logic levels are 2.8 volts regardless of the battery voltage.

If interfacing to 5 volts you will need level shifters otherwise erratic operation and or damage to the SIM908 will follow.

Cheers.