I am thinking of making a sort of a security device wherein a sensor is attached to the PIC and the PIC controls the GSM Phone to send SMS (using AT commands) to my phone when somebody or a burglar tries to open the door or window of my house. It could be used also to serve as anti-carnap device when somebody is turning on the car's ignition or break open the window. This can even be extended by sending SMS from my GSM to my house installed with this device to put the porch light on/off.

I have searched already but to no avail. Can anyone shed me light on this? :confused:

Posted on 2003-07-05 04:06:21 by Junix
Please clarify. I would say if you are generating AT signals then you need a modem. Maxim has a wide variety of chips for line controls.
Posted on 2003-07-06 17:15:43 by mrgone
GSM stands for Global System for Mobile Communication (i.e. Cellular phones)
SMS (SHORT MESSAGE SYSTEM) MOBILE TECHNOLOGY. The Short Message Service (SMS) allows text messages to be sent and received to and from mobile telephones.

I came across this url
and I am trying to figure out how can it be implemented using PIC. :confused:

Posted on 2003-07-06 20:29:54 by Junix
hi Junix, its looks like the circuit connected to nokia through a cable. shess! i was thinking that it can transmit sms through the air :P
i dont know is there any converter to change the delphi source to pic assembler. maybe someone would answer that soon. i was read about serial? sms vs serial? i was confused here :(
Posted on 2003-07-07 06:10:01 by dion
Maybe I could better explain this way:


Let's say a SENSOR that is installed on the window would trigger the PIC to issue AT-Commands to GSM PHONE1 to send text messge to GSM PHONE2 that the window is being opened.

If however, I would like to issue command to a CONTROL SYSTEM, I would just use GSM PHONE2 to send text Message to GSM PHONE1. Since the PIC is monitoring the GSM Phone1 would determine the command on what to perform on the control system. The command may be to turn on the surveilance camera and make a recording; or anything you want the control system designed to perform.

As I understood it, an FBUS cable is being used to connect from PIC to GSM PHONE1.
AT-Commands of Modems are different from AT-Commands of GSM Phones.
PIC is being used instead of a PC to since it is not sensible (IMHO) to install a PC if you are implementing this device in your car. Though you could extend functionality by optionally connecting a PC for an added feature and control when this is installed in your house. :(

Posted on 2003-07-07 07:04:44 by Junix
Hi Junix
You need any GSM modem.
I solved the similar task with help "TC35 Terminal" of SIEMENS.
You need the file "tc35_at_e_251169.pdf"
Posted on 2003-07-07 08:47:00 by MikDay
Look up data sheets on National Semi-conductor NS16450 family USARTs. This mobil communication protocal is not the same as cell? Because Cellular AT commands are the same with additions. You see he is using the Maxim Max232. To be honest and not bragging at all but I could design this thing if I had the time or was doing job in this venue. Be as specific as possible and I will help in stages.
Posted on 2003-07-07 18:46:53 by mrgone
Hello MikDay,


I looked at TC35 Terminal datasheets from Siemens and I find it doable. However, I am a bit short of cash to shell-out for the TC35 terminal.

I am not actually an electronic expert. I am just beginning as an electronic enthusiast and would want to share this project at the school wherein I am currently connected with. I am going to make this project during my free time because I am a computer programmer and quite busy these days.

Anyhow, for fast prototyping, I am going to try it first using a PC through FBUS serial interface and if this works I would then try using PIC since our school is using PIC for their electronic laboratory projects. Besides, the in-circuit emulator/programmer for PIC is very affordable for most students including yours truly.

However, I am not yet familiar with the programming of PIC. Although I already have the resources and technical details I still have to study on how to go about it.:(

So, that is why I am asking help if anybody has implemented this kind of project just using PIC to speed up the development and would also save the students and myself from buying the terminal.

As for MrGone, thank you for the suggestion. I also have checked the NS16450 UART of National Semiconductor . I even checked some of their Application Notes and came across the AN-739 which is "RS-232C Interface with COP800". I find it feasible as an alternative but I still have a lot to learn. although I am also considering the use of this type of implementation.

For now, I am just gathering all necessary informations and the requirements I need before I would commence delving into this project.

Again, thanks!
Posted on 2003-07-08 00:26:34 by Junix
Sounds interesting. If you've not used PIC before this program may help you avoid a learning curve . You can quickly machine code your PIC programs then convert them to hex file format.
Posted on 2003-07-08 12:31:33 by mrgone
hi, yea your idea will be very easy to implent.. :)

you can use either at commands or nokia m bus protocol commands for sending sms via your PIC's M bus connection.
doc's on both can be found in

pic program would be very simple to write in asm (maybe i'm biased there though..)
just use interupts on pic or simple bit test file command on your sensor to call subroutine where you output the hex values used in m bus protocol, for at commands i'm not sure about outputting

Posted on 2003-07-15 12:59:31 by wilson