1PCS GSM module SIM900A V40 Kit Wireless Extension Module GSM GPRS Board Antenna Tested Worldwide Store Features: The onboard two set power supply interface VCC5 5V power supply, VCC4 interface, 3.5--4.5V power supply, optional power on self starting (default) and control start. The onboard SMA (default) and IPXmini antenna interface, SIM900A interface reserved reset. The size of the module is 49*50, all the new and original device. The computer can give early computer debugging USB module power supply, a very large amount of data under the condition of the recommended current more than 1A. Standby dozens of MA data can be set to provide dormancy, dormancy of 10MA low power. Support 2, mobile phone 3,4G card. The serial port circuit: support for 3.3V single chip microcomputer. TTL serial port support 3.3 and 5V single chip microcomputer. The SIM card circuit to increase the SMF05C ESD chip. Antenna circuit: guarantee short and straight, so as to ensure the signal strength. PCB display screen printing mark: each interface, convenient development two times, the SIM900/A hardware is completely follow the design when the design manual. Two power supply interface: VCC5, 5V DC above 1A. Computer 5V power supply can be early computer USB. DC long data circuit over larger recommended 5V1A. VCC4, 3.5--4.5V power supply, ibid., suitable for lithium battery. Control pin all leads. A TTL level, compatible with 3.3V and 5V. The two antenna interface, the default SMA straight head, connector for IPXmini antenna. One way of speech interface, the way Mike interface. The control interface of each pin description: GND - GND SIMR SIM900A RXD, TTL level, can not be directly connected to the 232 level SIMT SIM900A TXD, TTL level, can not be directly connected to the 232 level RST - SIM900A reset, active low VCC_MCU when the SIM900A module and 5V TTL level communication, this pin is connected to DC 5V; when the level of communication of SIM900A and 3.3V TTL, this pin is connected to DC 3.3V. VCC5----DC 5V input. VCC4------DC3.5--4.5 input Onboard Resources: Serial port circuit(with protection) Antenna interface circuit(SMA bend female port) SIM card circuit(flip SIM slot) 4*3.5 fixture hole 4pcs SIM900A serial port output terminal Specifications: Size:49mm x 47mm Net Weight:28g Weight: 38g Package Included: 1 x SIM900A V4.0 kit 1x Power Cable 1x Antenna _x000D_ _x000D_