AT89S52 and modem interfacing

9780id · May 29, 2013

hi friends,I made a project to turn on and off light using SMS.
So if I send LAMP ON the lamp will turn on and the circuit will send back LAMP IS ON.
I know there are many thread similar problem with mine,but I haven't found the thread that already discuss about it completely.
and I also want to ask about interfacing modem and microcontroller.
I use Wavecom 1306B, does anybody have the link for that?
your help is mean a lot for me.
thanks

anboli · May 31, 2013

**broken link removed**

http://obrazki.elektroda.pl/11_1287736767.jpg

**broken link removed**

http://www.microchip.com/forums/m642241-print.aspx

- - - Updated - - -

9780id · May 31, 2013

hi anboli,thanks for the reply.
but that was for arduino and PIC.
i am new in programming here
do you have that using 8051 and in C language?
thanks a lot

amayilsamy · May 31, 2013

Post your project block diagram.

How to you interface the modem with micro controller.

anboli · May 31, 2013

while you posting the queries, you need to specify the controller and other details. then only we could help.

give any circuit or anything about your project, at where you having problem now?

9780id · Jun 3, 2013

hi friends,I used AT89S52,xtal 11,0592 MHz and max 232 for this project.I dont use any LCD
I just try a simple code but it not works
can you help me examine it?

g_shyam1682 · Jun 4, 2013

Hi friend,

I have seen your whole code, in your main loop you first init GSM and then serial communication. How it is possible that GSM AT command work without serial communication initialize,
So, first init serial communication then send AT command to you GSM module.

Best of Luck.

Regards,

9780id · Jun 4, 2013

hi g_shyam1682,thanks a lot buddy..
i now can send sms

9780id · Jun 5, 2013

hi,I got another question.
now I am trying to read and sms,i found references code on the internet,but i dont get what does that mean.
can somebody help decode it?

Code:

void tx_data(unsigned char tdata)
	{
    	TI=0;
		SBUF=tdata;
		while(TI==0);
	}
/************************************************************************************/
void tx_string(unsigned char *tstring)
	{
		unsigned char i=0;
		while(tstring[i]!='\0')
		{
			tx_data(tstring[i]);
			i++;
		}
	}
/************************************************************************************/
unsigned char rx_data()
	{
		while(RI==0);
		RI=0;
		return(SBUF);

	}
/************************************************************************************/
void enter()
{
	tx_data(0x0d);       //  <CR>
	tx_data(0x0a);		// <LF>
}

- - - Updated - - -

hi,I got another question.
now I am trying to read and sms,i found references code on the internet,but i dont get what does that mean.
can somebody help decode it?

Code:

void tx_data(unsigned char tdata)
	{
    	TI=0;
		SBUF=tdata;
		while(TI==0);
	}
/************************************************************************************/
void tx_string(unsigned char *tstring)
	{
		unsigned char i=0;
		while(tstring[i]!='\0')
		{
			tx_data(tstring[i]);
			i++;
		}
	}
/************************************************************************************/
unsigned char rx_data()
	{
		while(RI==0);
		RI=0;
		return(SBUF);

	}
/************************************************************************************/
void enter()
{
	tx_data(0x0d);       //  <CR>
	tx_data(0x0a);		// <LF>
}

jayanth.devarayanadurga · Jun 5, 2013

tx_data() is for transmitting single byte through uart and rx_data() is to receive single byte. tx_string() is to transmit a string. You have to use Serial interrupt for reading data. Whenever there is a serial interrupt you have to put the received data byte into an array and increment the array index and after all data is received terminate the array with a null string so that it becomes a string which can be displayed on Serial Terminal or LCD.

9780id · Jun 5, 2013

how can I activate serial interrupt?can you give a clear explanation of that?
and I'm also not unsure about this matter

Code:

void read_nd_check_password(unsigned char msg_array[])
{
if(Pass_array[0]==msg_array[59]&&
	Pass_array[1]== msg_array[60]&&
	Pass_array[2]==msg_array[61]&&
	Pass_array[3]== msg_array[62])
	{
		display_msg();
	}
	else
	{	
	SMSString("AT+CMGS=\"");
	SMSString(Mob_no);
	SMSString("\"\r");
	delay(1);
	SMSString("Password Incorrect!!");
	tx0(0x1A); // Ctrl+z
	delay(10);	
	}

the meaning of Pass_array[0]==msg_array[59] is if the pass_array contained in array number 0 is the same is with the msg_array number 59.Is that true?

jayanth.devarayanadurga · Jun 5, 2013

If Pass_arry[0] element 0 matches with msg_array[59] element 59 and similar matches then display message else send SMS password is incorrect. Before that it is reading the SMS and msg_array[] contains the SMS. element 59 to 62 of msg_array[] contains the password. For serial interrupt refer to book "The 8051 Microcontroller and Embedded System Using Assembly and C" by Muhammed Ali Mazidi.

https://www.8051projects.info/resources/a-rewrite-of-the-serial-example-to-use-interrupts-in-c.60/
https://saeedsolutions.blogspot.in/2012/05/interfacing-with-uart-of-8051.html

anboli · Jun 6, 2013

this sample program for the receiver serial interrupt..

void serial (void) interrupt 4 // giving the interrupt priority
{
static char temp = '\0';

if (RI == 1) // it was a receive interrupt
{
temp = SBUF;
RI = 0;
TI = 1;
}
}

g_shyam1682 · Jun 6, 2013

Hi friend,

I read your whole thread, i think if you don't know how to interface on serial port, how to work RX, TX, then GSM communication or SMS is the far away from you.
I suggest you first study Serial interface over microcontroller, hands on serial interface then start work on SMS.
There is also "8051 Microcontroller by Ayala" book to study complete microcontroller. It is very easy to understand.

Regards,

9780id · Jun 7, 2013

jayanth.devarayanadurga said:
If Pass_arry[0] element 0 matches with msg_array[59] element 59 and similar matches then display message else send SMS password is incorrect. Before that it is reading the SMS and msg_array[] contains the SMS. element 59 to 62 of msg_array[] contains the password. For serial interrupt refer to book "The 8051 Microcontroller and Embedded System Using Assembly and C" by Muhammed Ali Mazidi.

https://www.8051projects.info/resources/a-rewrite-of-the-serial-example-to-use-interrupts-in-c.60/
https://saeedsolutions.blogspot.in/2012/05/interfacing-with-uart-of-8051.html

thank you friend,but how can you save a data in a certain location of array?
i thought array will be saved randomly.

jayanth.devarayanadurga · Jun 7, 2013

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
unsigned int i = 0;
 
void serial (void) interrupt 4 // giving the interrupt priority 
{   
 
i   f (RI == 1) // it was a receive interrupt 
    {
        msg_array[i++] = SBUF;
        msg_array[i] = '\0'; 
        RI = 0; 
        TI = 1; 
    }
}

9780id · Jun 7, 2013

still i can not get it (
can you give me sample how to read sms?

jayanth.devarayanadurga · Jun 7, 2013

You have to issue AT+CMGR=X Command. X will be the index of message. The message will be read into the array by serial interrupt code.

9780id · Jun 7, 2013

yes,i know i should use AT+CMGR=index message.
but I can not program it to microcontroller,I really dont understand how it can be done.

Golden Electronics · Jun 7, 2013

I Suggest some time on following work which give u better understanding of Controller

1. How each pin work & how to assign to particular task.
2. How crystal block work what setting required for external & internal type required.
3. Use LED & timer to generate specific time say 100 ms 200 ms etc & blink LED in ISR or
Main loop
4. How serial Communication work what setting it required for B.R. generation according to
crystal value.
5. Then just Send few Character & similar for Reciving
6. After that just send AT command for SMS read. Check command on hyper terminal. Note: If same command is send by PC to GSM then SMS read action should occur. Else correct command used & then same command used in controller.

U may feel time consuming but if u know each step well then ur work easier for this project as well as future work also. U can ignore any step if u have expert it on the same

AT89S52 and modem interfacing

Junior Member level 1

Full Member level 2

Junior Member level 1

Advanced Member level 1

Full Member level 2

Junior Member level 1

Attachments

Full Member level 4

Junior Member level 1

Junior Member level 1

Banned

Junior Member level 1

Banned

Full Member level 2

Full Member level 4

Junior Member level 1

Banned

Junior Member level 1

Banned

Junior Member level 1

Full Member level 5

Similar threads

Privacy & Transparency

Privacy & Transparency