Hi there!
I've just owned a Sim808 module, and I've successfully connected it to my Arduino Uno. By the moment I don't have a sim card connected to it, so I want to test GPS acquisition data without GPRS connection.
This is the module:
https://www.amazon.com/Development-Antenna-Support-Raspberry-Geekstory/dp/B079FN45FB
I've a question. I see, I need to switch on the module but holding almost 3s the start button, then status LEDs blink and I can send AT commands. After a few minutes without the SIM card, the LEDs stop blink and no AT commands could be sended to the module, so the serial connection is closed... Is this a normal functionality?
After that, it won't to connect already by pressing the start button. The status LEDs don't blink, and the connection still being closed...
How can I solve this situation? It is obligatory to have always a SIM card connected?
In the other hand, if I've the module outside my site, and power supply go down, and go up, is it necessary to hold the start button again? That's a problem for my future project, because the module will be placed into a car, and it will not be possible to access it by my self...
Thanks a lot!
Best regards,
Jordi Marqués