The power supply is 5 V. TTL serial port is compatible with 3.3 V and 3.5 V for single chip Microcomputer. The IPX antenna can be converted to any PCB amtenna. SIM800L allows. Universal communication.
Power of 5 V power interface
Connect to DC5v
VDD TTL UART serial interface, you can connect the MCU as 51MCU or arm or MSP430 directly. The VDD pin is used to equalize the TTL voltage.
GND if this pin is not used, it is still open
First the module first, if this pin is not used, it is still open