Embedded project

[pratish]

hey frnds, i m doing my project on RFID (Radio Frequency Identification) using AT89c51 microcontroller . My problem is that i want to take input from Port3 n want to send output on same port but on some different pin...
So I want to know dat can we configure particular pin of da port...

for e.g.
P3.2=1;
P3.5=0;

Is this possible ...
Thnax

[RedSon]

First, if you have better grammer and spelling skills you should use them. Your question will get more attention and responses if it is well formatted and people dont have to read stuff like "dat" and "da".

That being said here is some information taken from the product documents:

Port 3 is an 8-bit bi-directional I/O port with internal pullups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current because of the pullups. Also, Port 3 also serves the functions of various special features of your microcontroller , specifically P3.5 is an external timer input. You may want to consider using a different port that is not serving the special features of your chip. Port 1 is 8-bit and bi-directional and can also source four TTL inputs, but it has an added bonus as not serving the features that are inherent in the microcontroller . If I am looking at the correct documentation of your microcontroller , it looks like you can pull all the pins high and use them for input, store the bits you want to in the buffer, then pull the pins low again to output the bits in the buffer. But it would require a change in the directionality of all the pins, from input to output (or vice versa).

[Motoma]

You may be able to just perform a logical AND operation with the Port and an Integer with the correct bit set.

[pratish]

Thanks for replying my query and also sorry for using improper language.
Now, i tell you in more detail.
Now.... i am giving you pin description for my project..
PORT1-------
P1.0 and P1.1 ------LEDs are connected.

PORT2-----
P2.0 -------- one buzzer is connected.

PORT3--------
P3.0-----RXD
P3.1-----TXD
P3.2-----RFID Tag 1


LOGIC
----------

When RFID Tag1 i.e P3.2 gets signal, it will send signal to P3.1through which the output is been given to computer.
IF RFID Tag1 i.e.P3.2 doesnt get signal then glow the LED which is connected to P1.0 and ring the buzzer which is connected to P2.0.


--------------------

This is my basic testing code.
If i am able to do this, i will proceed further with some complicated things......
So please help me out friends.

[Motoma]

PORT1-------
P1.0 and P1.1 ------LEDs are connected.

PORT2-----
P2.0 -------- one buzzer is connected.

PORT3--------
P3.0-----RXD
P3.1-----TXD
P3.2-----RFID Tag 1

LOGIC
----------

When RFID Tag1 i.e P3.2 gets signal, it will send signal to P3.1through which the output is been given to computer.
IF RFID Tag1 i.e.P3.2 doesnt get signal then glow the LED which is connected to P1.0 and ring the buzzer which is connected to P2.0.

--------------------

This seems to be a little different than your original question.
If I understand your system correctly, pseudocode for your program will look a little like this:

while(1)
{
  if(recieved() == 1) {
    //unset LEDs
    PORT1 = PORT1 & 0x3F; // 00111111
    //do signal processing
    dorecieved();
  } else {
    //set LEDs
    PORT1 = PORT1 | 0xB0; // 11000000
    dobuzzer();
  }
}

int recieved()
{
  return PORT3.2;
}

void dobuzzer()
{
  (pulse width modulation for loop)
  {
    if(up == 1)PORT2 = PORT2 | 0x80; // 10000000
    else PORT2 = PORT2 & 0x7F; // 01111111
  }
}

Maybe I'm just way off.

[horace1]

hey frnds, i m doing my project on RFID (Radio Frequency Identification) using AT89c51 microcontroller . My problem is that i want to take input from Port3 n want to send output on same port but on some different pin...
So I want to know dat can we configure particular pin of da port...

for e.g.
P3.2=1;
P3.5=0;

Is this possible ...
Thnax

try

P3_2 = 0;
P3_2 = 1;

[pratish]

thanks friends...
I m also having problem wid serial communication.. .
I dont know how to use UART...
Please help me ..

[Motoma]

thanks friends...
I m also having problem wid serial communication.. .
I dont know how to use UART...
Please help me ..

You are going to have to give a little more information if you want our help then.

[horace1]

thanks friends...
I m also having problem wid serial communication.. .
I dont know how to use UART...
Please help me ..

try this

//*************************************************************************
// Using 16Mhz clock
// Timer 2 is used and therfore the Reload value needs to be caluclated
// i.e
// reload value for RCAP2H and RCAP2L = 65536 - (osc freq/32* BaudRate)
// 65536 - (16Mhz/16*9600)  in X2 mode (/2)
// 65536 - 104
// 65432 or FF98 in hex
// therefore 	RCAP2L = 0x98
//				RCAP2H = 0xff
// This gives 9600b/s
//*************************************************************************

void serial_init()
{
	T2CON 	= 0x30;			// use timer 2 to rx & rx serial clock		
	RCAP2L 	= 0x98;			// Reload value for Hi/Lo byte of T2 
	RCAP2H 	= 0xff;
	TL2 = 0x98;				// Set the same reload value for the first clock
	TH2 = 0xff;

	SCON = 0x50;			// 8bit Uart + Enable Reception on Rx
	TR2 = 1;				// enable Timer 2
	TI 	= 1;				// enable Transmission
	CKCON |= 0x11;			// Divide clock by 2

}

void hexout(unsigned char v)
{
	hex(v>>4);
	hex(v);
}

void hex(unsigned char v)
{
	v &= 0x0f;
	if (v > 9) putchar(v + '7');
	else putchar(v + '0');
}

once initialised you should be able to use putchar() and printf("hello\n ")

[pratish]

Thanks Friends...
Now my Circuit is working very fine..
Now the problem is, i dont know how to do serial communication.
More precisely....

Let me give you pin description
In My project i have.
P3.0/RXD ----------RXD
P3.1/TXD ----------TXD
P3.2/INT0 --------RFID TAG 1
P3.3/INT1 ---------RFID TAG 2
My project is RFID in which i have two RFID transmitters.(T ag 1 and Tag 2).
So when RFID TAG1 is in range,P3.2 gets signal, and it should show the message on the hyperterminal that"Tag1 is in range"..Same for "Not in range".

So My problem is that i dont know how to do serial communication .
I have used MAX232 for the same.

.....
I have done the serial communication with AT90s8535...In which i have used UART.
I know that for enabling TXD and RXD, we have to use UCR
For setting baud rate , we have to use UBRR
For input output , we have to use UDR...
These are the registers used for serail communication .....
But I dont know how to use same in AT89C51.
Please help me out.....