Technical issues that mean various problems that have occurred during the project of mobile interfacing are given below:
- Microcontroller can communicate with other devices through serial interfacing protocol, but most of the recent mobile use USB protocol for data communication. So, there is a problem in interfacing microcontroller with mobile. The use of serial to USB converter or USB to serial converter is not helpful since this converter only converts the data from one protocol to another but does not convert the protocol that is required. So it is necessary to find a mobile set that supports serial data communication protocol, example: Siemens A75, Siemens A70 etc.
- The project of mobile interfacing is based on the AT command (Attention Terminal). To read messages stored in the mobile AT command are send to the mobile from the microcontroller. But for this procedure the mobile must support the AT command. Mobiles which support the GSM technology also support AT command. Without supporting this technology the interfacing is not possible.
- The SMS (Short Message Service), through which AT command is sent to the mobile is based on two modes: Text mode and PDU (Packet Data Unit) mode. Mobile that supports text mode does not need extra decoding code but for mobile that supports PDU mode an extra decoding code should be added to the microcontroller code to convert the text data format to the PDU data format.
- It is essential to use a MAX 232 buffer IC as an interlink between the microcontroller and the mobile rather than direct contact between these two devices. This MAX 232 buffer IC keeps the voltage level constant.
This is a time worthy project. It requires 5 to 6 weeks of time. So, it is better to keep in hand minimum 6 to 8 week time to complete the whole project including PCB.
Where to get things from:
The electrical components can be found from any of the electrical market in Patuatuli or Stadium Market. The mobiles are found in Motalib Plaza.
Suggestive Resources (Links):
Here are some links that will be useful to the project of mobile interfacing: