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Cell phone Car alarm project

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Sid58ney

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Hi
Before I send this post, believe I already searched a lot on internet and this forum. I just need gathering more information i need
I have simple project to make car alarm system to use old GSM phone to send message to alert my cell phone. My plan is use proximity motion sensor to be a detection device, once detect the motion from sensor the PIC16F84 will send message through the cell phone to me.

Now; my problem is
1. Is PIC16F84 is able to send AT command or F-bus to cell phone?
2. My old GSM phone is Nokia 1208A; I believe it uses F-Bus, am I correct?
3. Any recommendation cell phone I should use to simplify my project? For example; use cell phone which support AT command instead F-BUS

Thank you

Sidney
 

Last edited:

Hi,
The voltage level on Nokia pinout is ~3.3v. If power the Pic16f84 with 3.3v connect the pic directly with phone!
If power the Pic16f84 with 5v you need to use a resistive divisor for voltage (5V -> 3,3V)

5V o---R1----o-----R2-----GND
|
Nokia

R1=4,7k and R2=10K!
 
Hi,
The voltage level on Nokia pinout is ~3.3v. If power the Pic16f84 with 3.3v connect the pic directly with phone!
If power the Pic16f84 with 5v you need to use a resistive divisor for voltage (5V -> 3,3V)

5V o---R1----o-----R2-----GND
|
Nokia

R1=4,7k and R2=10K!

I have to say, I totally lost now, the more I search and the more I confuse. here is my question after reading many website.

1. Can I use Pic16F84A to be a interface to send SMS message by using AT command? as the result I had searched, the Pic16f84a doesn't has USART so it can not be used as a interface to communicate with cell phone, is this true? if it is ture, whic Pic chip I should use?

2. If I looking for the list of model for the cell phone which support AT commands, where can I go search? I been searching for many website but still not really clear.

Thank you
 

Hi,

there is a good reason for you to get confused at this stage...

let me answer your questions
1. Can I use Pic16F84A to be a interface to send SMS message by using AT command? as the result I had searched, the Pic16f84a doesn't has USART so it can not be used as a interface to communicate with cell phone, is this true? if it is ture, whic Pic chip I should use?

Ans: you can use a method called bit banging ,, but it would complicate your work... Since it does not have UART/USART, i recomment you to migrate to PIC16f877 or any series which has USART inbuilt.. dont use f84A as it has some disadvantages compared to other PIC controllers....

2. If I looking for the list of model for the cell phone which support AT commands, where can I go search? I been searching for many website but still not really clear.

All the phones supports AT commands, which supports serial communication. Search for mobiles supporting serial communication in google for results....
 

Hi

For 16f84A you can emulate the hardware USART with a software function! If you need you can send a demo for this!
What compiler you use?

I test the phone SE T230,T290 and Sagem Mw3026 with AT Command. But more phone suport this protocol!
 

Hi All,
First, Thanks for both of your big help, I think I got clearer picture after read your post now. Basically; the best way to communicate with cell phone by using PIC16f877 or else with UART/USART inbuild, the MAX3232 or 232 is needed for voltage conveter to change from 5v to 3.3.v, correct me if I am wrong.

Thanks

---------- Post added 30-08-11 at 00:09 ---------- Previous post was 29-08-11 at 22:16 ----------

Hi

For 16f84A you can emulate the hardware USART with a software function! If you need you can send a demo for this!
What compiler you use?

I test the phone SE T230,T290 and Sagem Mw3026 with AT Command. But more phone suport this protocol!

Do you mean "you can send me a demo"? yes please if you have..

Thanks
 

Hi,

//Procedura de TX un caracter catre PC
void SendCharPC(byte data,byte delay)
{
byte io_bit,count;
//bitul de start
output_bit(TX,0);
delay_us(delay);
//8 biti de date
for(count=1;count<=8;count++)
{ io_bit= data & 0x01;
if(io_bit==1)
output_bit(TX,1);
else
output_bit(TX,0);
delay_us(delay-1);
data=data>>1;
}
//1 bit de stop
output_bit(TX,1);
delay_us(delay);
}

This function is writed for CCS compiler.
Parameter 'delay' depends on the frequency of the pic and baud rate of serial port!


You do not need MAX232 ! You find here : The UUUSB board a simple schematics for level convertor!
 

Hi.
If later on if I want to add GPS fucntion can I still use PIC16F628? or I should change to something else?

Thank you
 

there are 3 options.
1. use an integrated GSM and GPS module and use single UART
2. If the GSM and GPS are different modules then use a relay to switch between the two devices using single UART.
3. Go for PIC with Dual UART.
 

hi!
is easy! duplicate the soft function with another pinout from pic !
 

Thanks for reply, actually up to now; I have electronic components ready but I still try to decide what should I use for GSM modem, use cell phone be a modem? of just buy GSM modem, can't make decesion for a week already, anyone can tell me what is pro and con to use either one of them.

For my self, I have few concern below

GSM modem
Pro
easy to communicate with microcontrollwe by using AT command

Con
There is no display to monitoring the status.

GSM phone
Pro
With disply and easy to read the status of phone

Con
Didn't find phone support with AT command, all three phone I have right now are Nokia and use Fbus, I still have no clue how to use Fbus to send the SMS message and control the device by receive the message

Sidney


Thanks

Sidney
 

Hi Sid58ney

Can u tell me the above mentioned connection have u made, bcoz the same problem i am facing
 

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