The onboard two set power supply interface VCC5 5V power supply, VCC4 interface, 3.5–4.5V power supply
The onboard SMA (default) and IPXmini antenna interface, SIM900A interface reserved reset.The computer can give early computer debugging USB module power supply, a very large amount of data under the
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.
The control interface of each pin description:
SIMR SIM900A RXD, 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.
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
Size:49mm x 47mm