Single chip microcomputer controls mobile phone to send short messages.

I made a home safety device last year, which is similar to the application you mentioned. Now I provide the following information for your reference:

1. Hardware design: MCS-51compatible single chip microcomputer is selected, I use windon 78 e 58 b, and then use GSM module of Motorola G20. The external SIM card circuit and 3.3v power supply circuit are designed by ourselves. The GSM module is connected with the serial port of the single chip microcomputer through a serial port and is controlled by instructions. Another 433MHZ wireless receiving module is used, and one of its contacts is connected to the I/O port of the single chip microcomputer. When the monitored equipment (the inductive switch in the safety door) is triggered, the 433MHZ wireless transmitting module sends a RF switch signal to the corresponding receiving module, and the receiving module outputs the switch signal to the I/O port of the single chip microcomputer. After the MCU program detects the I/O signal jump, it sends an instruction to the GSM module to send a short message to the designated mobile phone, which can monitor multiple monitoring points at the same time.

2. program: c language. Please refer to G20 instruction manual and AT instruction manual for details. Both the program and the hardware run through, which is feasible.

3. Please pay attention to the level conversion between GSM and MCU when making, one is 3.3V and the other is 5V, which should be handled well.

I hope the above can help you. If you still don't understand or have questions about the program description, please contact gz119 @ 21cn.com.

Supplement: the above scheme is used for the design of specialized products, and it is more troublesome to do it under amateur conditions. If you just play with it yourself, you don't need to use GSM module, just speed up the single chip microcomputer test board and connect it with a cheap old mobile phone with serial port. If you can't find a serial phone, you can use an old Nokia phone with infrared port to transform it. Good luck!