Development board introduction:
Power supply requirements: 5V-18V power supply, current needs to provide 1.5A or more;
The TTL level serial port is compatible with 3.3V and 5V microcontrollers. Really can communicate directly with microcontrollers such as 51/STM32/MP430;
When using computer debugging in the initial stage, it is recommended to use the CP2102 USB-TTL module to power and communicate the module;
When using the MCU control module, you can also use the USB-232 monitoring module to return the data to the command, which is very convenient to find the problem, especially suitable for the 51 MCU partners.
Standby at around 30MA, you can set the sleep state to low power consumption around 10MA.
Support SMS, GPRS data transmission, send MMS, DTMF, HTTP, FTP, PPP dialing and other functions.
At the same time, the hardware contains a reset pin. This pin reset can be used when there is a problem with the module.

The advantages of this module:
Serial port circuit: TVS and magnetic bead protection devices are used to protect the board, so that the board will not be damaged by surge and high voltage.
SIM card circuit: Add SMF05C electrostatic release chip.
Antenna circuit: guaranteed to be short and straight so as to ensure signal strength.
PCB display: Each interface is screen printed, which is convenient for secondary development. The design is completely in accordance with the SIM900A hardware design manual.
All the way 5-18V power supply interface: We have done protection, even if it is reversed, it will not burn the board.
One way TTL interface: support 3.3V microcontroller and 5V microcontroller. In other words, it supports 51V 5V and STM32.
Two antenna interfaces: SMA antenna interface, IPX MINI antenna interface (not soldered by default).

Shipping list:
Sim800a module *1
GSM module antenna *1
Module power cord*1