IOT- SIM808 GPS Tracker Based on Arduino

We solved the power problems , by now. ~
1.  The Maduino Zero-SIM808 GPS tracker can be powered either by Lipo battery, or DC 5V, 2A.   The USB is only for data communication, or programming, but not for power.  Many ursers previously ask me why the USB do not power up the board, it is just their USB from PC support too small current(it need to be 2A, but most PC USB port only supply 500 mA).

2. Seperate DC-DC circuit added, using MP1584.

3. On-board charger

Besides, the Bluetooth also open and antenna added the board, to make the Maduino Zero- SIM808 GPS tracker also suppot Bluetooth + EDR

Serious problems in the testing of V3.4 version.  As the testing, the max current can be upto 2.5A when SIM808 powerup.. the 3.4 DC power circuit do not bears so big transient current, that make the SIM808 do not powered up .:-(.. although this circuit works with A9G, but SIM808 needs much bigger current...

So we update again , to the version 3.5, and slves this problem ultimately. 

Updates in the version 3:

1. Power circuit update: previously a 3.7v battery is needed as the A9G power supply. 

in the new version 3, the module can be powered either by battery , or directly by USB.

2. Battery voltage Monitor, to check the battery voltage

3. USB voltage monitor, to check if there a USB power connected;

4. 3.3V DC-DC module updated to 1A Version

5. SIM808 DTR connected to MCU, to make SIM808 enter sleep mode