Introducing new TTL Modem with Dual band frequency of operation, SIM900A is a budget modem to fit applications requiring SMS/GPRS communication. The small form factor of our new SIM900A modem is suitable to fit it into small casing or space. It is also equipped with MIC29XX based high efficient low dropout regulator to enable the supply voltage to go as low as 4.5 Volt. The modem will operate reliably at 4.5 – 12 Volt range. 1 Ampere or more current should be provided for the GPRS applications.
Accessories required for interfacing with PC
- USB to TTL Converter
- 5V – 2Ampere power adaptor
- SIM Card
- SMA Antenna/Wire Antenna(comes with the module)
USB to TTL converters are used to transfer data to and from PC to the modem. Any TTL to USB bridge can be used for this purpose. A compatible USB to Serial converter can be purchased from our store. The chip is based on CP2102 USB bridge IC which well known for its stability and durability.
Note: Some serial converters have RS232 output. Do not connect RS232 level to the TTL pins of the Modem, doing so will damage the modem.
Conect the USB to TTL module as shown in the above figure.
Power the module using 5 Volt adaptor having sufficient current output. The current requirement is more than 1 Ampere for reliable operation of the module. The TTL module is designed to turn on the module as soon as the power is applied. There is no ON/OFF switch or buttons. Thus the module is ready to recieve commands as soon as the voltage is applied to the power jack.
Connect the USB to Serial converter to the PC. Check the communication port number in the device manager.
The device manager should have the PORT listed as below.
GSM test utility can be used to connect send data to GSM Modem through AT interface. The utility was actually developed for testing the SIM900A GSM modules manufactured by Elementz Engineers Guild Pvt Ltd. With the increase in demand and for quick testing we are providing the tool as a free software. The tool can be downloaded from our GitHub repository or from here.
See the instructions on our previous post to use the utility.