The SIM900 from SIMCom, which started out as a simple low-cost bit-piping modem, has been bestowed with new firmware upgrades to help it compete with top-of-the-range GSM engines. Over the past year, the full approval that the module has obtained from ICASA, MTN and Vodacom, has accelerated its, and SIMCom’s, acceptance in the South African market.
The SIM900 is a quad-band, surface-mount castellation layout device with a low-power ARM9 core. It now features full FTP support, as well as a full multiplexer. The firmware also now supports Embedded AT, giving developers access to code space on the GSM engine itself, as well as control over 24 GPIOs, 10 timers, a display interface and more. The module has added jamming detection to its list of features, as well as the possibility to interface to the SIM08 GPS front-end, with all processing taking place within the SIM900.
The module’s FTP functionality embedded in the firmware allows it to utilise GPRS communications to transfer large amounts of data between remote sites. Traditionally, in the absence of FTP capability, setting a GSM/GPRS module up in GPRS mode and getting it to connect to a predefined DNS or IP address with the port name is only half the battle. On the server side, specific ports need to be opened and a program needs to be written to service these ports for incoming connections. The program must recognise the incoming connection, open the socket, send and receive data and then close the socket. The received data then needs to be stored in the required file format. When a large amount of data is sent, the process of data transfer becomes more complex, slowing down the entire system from product to server. The SIM900’s FTP feature can assist in simplifying the GPRS setup and gaining the advantages of increased speeds and decreased costs.
Using FTP on the SIM900 will allow a product to put a file on the designated FTP server in the default path and then start sending data to it. When done, the user can send an AT command to close the file. In this way, the complete file exists on the FTP server; there is no need to develop software that takes data and compiles it into a file. The only software required is that needed to open the file, read the data and close the file. The data that was read can then be used for whatever purposes it was obtained, such as the compilation of graphs used for statistical purposes. The created files on the FTP server also provide easier access and aid in record keeping. Should a file be required from the FTP server, the SIM900 can get the file from the default path and obtain the data.
A few simple AT commands are required in order to get the FTP service up and running. Some of the commands required are those used to input values to fields such as the connection type, APN, user name, password, FTP port, active/passive mode, FTP server address, FTP user name, password and so on. The other FTP AT commands are used for controlling the writing and reading of data to and from the file on the FTP server.
For more information contact Chris Viveiros, Otto Wireless Solutions, +27 (0)11 791 1033, [email protected], www.otto.co.za
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