My big problem is when I call the gps module with my mobile, it’s like if the module is switch off even if there is a green led flashing
I think it not good powered it is the reason why I was thinking about the pulse. I read thata pulse should be send to pin 1 of the GSM module, but I am not sure if I set correctely a puls
here are some other information but there is to much to read for you and I could not really understand what they seay. The support is totaly bad
Ground is 0V. That 4V is 4V relative to ground. Arduino 5V is 5V relative to ground.
If the grounds are not the same the voltages relative to them will not be 4V and 5V.
Connect all the DC grounds together unless you have completely isolated circuits
This 2 second pulse; should it be HIGH or LOW?
Is it for the SIM900 that you have the library? If so then doesn't the library have an initialize function that does that?
Yes the grounds MUST be connected together.
But you have another problem. If you put a 5V pulse into a module that is powered from only 4V then there is a chance you will fry it. Use a transistor to convert the voltage levels. This will invert the signal so invert it in software to componsate.
I read the doc and it sate 4V for the GSm module, the I created a small circuit (LM317) to have 4V.
But it does not really work
I join the GND and the GSM greed led flash 12 time and stop flashing.I think it's like if it turn off.
Is there another way to have properly 4V for the gsm module?