Simple Remote Control Implemented by ARM7 and GSM

Recently, I participated in an on-campus electronic competition. I had a question about using a single-chip microcomputer and GSM to achieve remote control. The control here is to control two v bulbs, SMS sending and receiving of single-chip microcomputer is required. After the competition is over, I learned a lot of new things and wrote a summary (for software, because I am responsible for software ).

The GSM module selects Siemens TC35i, which has a lot of information on the Internet. Some people have bought this module before, but if we use the GSM module directly, it will affect the competition performance. So we just bought the TC35I and SIM card slots and re-built the canvas by ourselves, draw arm and tc25i on a board. There is a lot of information about GSM control on the Internet, but many of them are controlled by 51. So our initial job was to learn TC35I andProgramTransplant to arm. Fortunately, it is not too difficult to control GSM alone. It is based on serial communication and all is based on AT command control. In other words, it is just familiar with commands, in addition, this competition also uses a relatively small number of commands, mainly about short messages. The commands we use are as follows:

At & F: if the current parameter is set to the vendor's default value, OK is returned if the parameter is successful.

At + CREG? : Network registration. + CREG: or + CREG: is returned. An error is returned.

At + cmgf = 1: Set the text message format to text.

At + csca = '+ 86xxxxxxxxxxxx': sends the local center number

At + cmgs = 'xxxxxxxxxxxxxx': sends the target mobile phone number.

At + cmgr = N: reads an SMS. N indicates the number of SMS messages.

At + cmgd = N: delete an SMS. N indicates the number of SMS messages.

Because it is just a simple control, you only need to transmit the ASCII code value. Therefore, the text message format is set to text, which reduces the programming burden.

It is our GSM control software flowchart:

In terms of serial communication, the ARM7 adopts FIFO reception, which is triggered in 8 bytes and has a character timeout interruption.

Is the circuit diagram of TC35I

In addition, the original use of arm was intended to use ucosii to complete the software design, but it was still useless to get it out near the competition. After thinking for a long time, I did not know where the error was, and finally gave up and ran bare metal. It seems that we should continue to learn about ucoⅱ and use it skillfully for programming.