SMS based notice board

[ckshivaram]

keil 2 supports 2K for 8051 and keil 3 suports 32k in evaluation whereas full version does not have any restriction... you can use keil 3 if you have it as now it is discontinued. it is replaced by keil4 with same features... so use keil 4 or 3 they are same....

 

[Wakuplil]

Is there no other safe way out to connect gsm modem? Just to connect 3 pins I av to get two 40pins MAX232 chip?

 

[ckshivaram]

max232 is not 40 pin but 16 pin chip.... and its not the question of just three pins but converting the signal to proper voltage level from TTL to RS232 and RS232 to TTL levels.........

 

[Wakuplil]

May i plz av the ckt of interfacing GSM modem to 8051, so that all doubts will be cleared in one go.

 

[Wakuplil]

In the program which was posted, Is it correct to set d baud rate as per below:
void uart_gps()
{
SCON=0x70;
PCON=0x00;
TH1=0xFD;
TMOD=0x20;
TCON=0x40;
}
Since i am using siemen300, baud rate needed is 9600bps.

 

[ckshivaram]

this code is like this

void uart_gps()
{
SCON=0x70;
PCON=0x00;
TH1=0xFD;
TMOD=0x20;
TCON=0x40;
}


the modified code should be

void uart_gps(void)
{
TMOD=0x20; /* timer 1, 8 bit auto reload */
SCON=0x50; /* serial mod 1, enable reception */
TH1=0xfd; /* set 9600 bps baudrate */
TR1=1; /* timer1 start */
}

 

[Wakuplil]

The syntax for AT+cnmi command is like this for the gsm modem I m using:
AT+CNMI=[<mode>],[<mt>],[<bm>],[<ds>],[<bfr>]

So in the program below command is according to this syntax????
gsm_cmd6[]="AT+CNMI=2,2,0,0,0"

May i plz kno the meaning of this code.

 

[e shade]

It means, configuring the modem to display messages with all details as time, date etc.without saving the message.

 

[Wakuplil]

void main()
{
UART_INIT(9600,Int); //To initalise the uart
gsm_init(); //To initalise the GSM
if(RI)
if(RI)
Recv_frm_mob();
TX_STR("AT+CMGD=4"); //clear the SIM memory
enter();
while(RX()!='O');
while(RX()!='K'); //waiting for the modem response
b="DEL";
display();
}
This is the change i have made in the code. I am doubtful about the line as under:
if(RI)
Recv_frm_mob();

RI can be high even if gsm is sending some response. So when to specifically call the function
Recv_frm_mob() ??

---------- Post added at 20:22 ---------- Previous post was at 20:04 ----------

In the posted program "AT+CMGR" is not used. Is it not needed?
I just want to know as soon as the new message is received, how to store it in micro controller memory?

 

[ckshivaram]

while(1)
	{	
		clear_display();	
		printLcd("   GSM MODEM    ");
		printLcd2("NOTICE DISPLAY ");

		no = recv_sms_no();		

		if(isdigit(no) && no != 0)
		{  
			clear_display();
			printLcd("SMS RECEIVED    ");
 			beep();        
			del_1s();

			read_sms(no);
                    }

unsigned char recv_sms_no()
{
    unsigned char volatile ch[14],i;

	while(i != '+')
	{
		i = recv_byte();
	}
	for(i=0;i<12;i++)	//sender's phone number
	{
		ch[i]=recv_byte();
	}
	clear_display();
	printLcd("SMS RECEIVED    ");
	beep();
	return(ch[11]);
}

unsigned char recv_byte()
{
	unsigned char c;
	while(!RI);						//waits till a byte is recieved
	RI = 0;
	c = SBUF;
	return(c);
}

 

[Wakuplil]

Thank you for all replies. I have learnt a lot from this forum. I hope my project gets successful.

 

[Wakuplil]

Will this connection of GSM modem with microcontroller will work?
My GSM modem has in built MAX3238I that's why i have used only one MAX 232 for interfacing.

 

[ckshivaram]

if your modem has max3238I then at the controller end also you should have one IC. check if the working of 3238 is same as 232.... 323 series have 3.3V tolerable and max232 uses 5V.. check it....

 

[Wakuplil]

max3238I specification is
3-V TO 5.5-V MULTICHANNEL RS-232 LINE DRIVER/RECEIVER WITH ±15-kV ESD (HBM) PROTECTION. It is 28 pin ic.
and we have used one max 232 ic at the microcontroller side.

 

[Wakuplil]

The interfacing diagram which i have uploaded is correct?

 

[Wakuplil]

same posted program's logic i have applied.But the microcontroller is not transmitting AT commands nor receiving the response
from the modem.the hardware connections are done using max232 to interface the modem and microcontroller using rs232
cable.

---------- Post added at 12:51 ---------- Previous post was at 12:49 ----------

please help

 

[Wakuplil]

I have programmed the microcontroller. When testing communication over hyperteminal, we receive 'AT', the first command from the microcontroller but the typed 'OK' response is not reaching microcontroller. So it is sending the second command 'ATE0'. I am not understanding what is a problem. Please help.

 

[ckshivaram]

there may be any one of these problems
1. your read routine is not correct or
2. check the pin connectivity of the serial cable pin 2,3 5 is shorted to other side of connector with 2,3,5 or 3,2,5 combination
3. change the max232 IC and try again...

check if the program is working on the serial window of keil software when you do the same operation...

 

[marky07]

Instead of gsm based,, im planning to make a project which is USB flash disk based... from the link below that i have read, is this USBWIZ with Philips LPC2141 microcontroller can be interface to the LED display for a message display?

**broken link removed**

im planning to design a message display board with a message or file from the USB flash disk...
is it difficult to send a file or message from the USB flash drive going to the microcontroller then it will be display to the LED board display??

 

[theultimateprasad]

Dear sir ..

I am too making this project (SMS based notice board) as my final yr project... My hardware configurations is same like using SIM300 modem+P89V51RD2BN mc+16x2 LCD...

My main problem is that i am getting problems in code writing... As i have not done any course in embedded system program so i always getting confused about code..

And this time i am very close to my submission time for project , So can you help me out in this topic?
Can you mail me the exact code that i needed ... I can understand the hardware interfacing as per declaration of port pins in code..

Thanks a lot

Regards,

Prasad.