The computer can provide early debug USB module power supply, a large amount of data under the condition of recommended current of more than 1A. Dozens of standby MA data can be configured to provide idle, low-power 10MA idle. Support 2, 3.4G card mobile phone.
Serial connection port circuit: compatible with 3.3V single chip microcomputer. Support TTL serial port
3.3 and 5 V single chip microcomputer.
The SIM card circuit to increase the SMF05C ESD chip.
Antenna circuit: guarantees short and straight, to guarantee signal strength.
PCB screen printing mark: each interface, practical development twice, the SIM900 / A equipment fully follow the design when the design manual.
Two power supply interfaces: VCC5, 5 V DC above 1 a. The 5V computer power supply can be early computer USB. DC data circuit long over larger recommended 5V1A. VCC4 power supply, 3.5-4.5V, id., Suitable for lithium batteries.
Check pin all cables.
One TTL level, 3.3V and 5V compatible.
The two antenna interface, the default SMA straight head, connector for the IPXmini antenna.
A form of voice interface, the form of a microphone interface.
The control interface of each pin Description:
GND-GND
SIMR SIM900 RXD, TTL level, cannot connect directly to level 232
SIMT SIM900 TXD, TTL level, cannot connect directly to level 232
RST-SIM900 reset, active low
VCC_MCU when SIM900 module and 5V TTL level communication, this pin is connected to 5V DC; When the communication level of SIM900 and TTL of 3.3V, this pin is connected to 3.3V DC.
VCC5 ---- DC 5V INPUT.
VCC4 ------ DC3.5--4.5 input