[PIC] How to interface EM-18 RFID reader with PIC16f628A using MikroC pro

[Mrunal Ahirrao]

Hi all,
I am trying to interface RFID reader with PIC16F628A using UART but it doesn't work. I tried using MikroC libraries but failed, so I tried by manual declaring all registers associated with USART. But it again failed. Any help would be appreciated.

sbit LED at RB3_bit;
unsigned char rdata[12];
unsigned char idata[]="84008159124E";
unsigned short i;

void interrupt()
{
 if(PIR1.RCIF==1)
 {
  rdata[i]=RCREG;
  i++;
  }
}



void main()
{
CMCON = 7; // Disable Comparators
TRISB = 0b00000110;
SPBRG=25;		// Fill SPBRG register to set the baud rate
RCSTA.SPEN=1;			// To activate serial port (Tx and Rx pins)
RCSTA.CREN=1;			// To enable continuous reception
PIE1.RCIE=1;			// To enable the Reception (Rx) Interrupt
INTCON.GIE=1;
INTCON.PEIE=1;
TXSTA.BRGH=1;
TXSTA.SYNC=0;


do{
if(rdata==idata)
{
LED=1;
}
}while(1);
}

The LED should lit but it doesn't!

 

[embRTS]

EM -18 RFID Cards work on 12 byte data transfer
And first you check a basic code of sending and receiving it to PC via UART using Mikeo C ,
so that it's assured that there is some problem after that we'll discuss on RFID Interfacing

 

[Mrunal Ahirrao]

EM -18 RFID Cards work on 12 byte data transfer
And first you check a basic code of sending and receiving it to PC via UART using Mikeo C ,
so that it's assured that there is some problem after that we'll discuss on RFID Interfacing

yes the same idea I followed to first check my UART communication. But it failed!
here is the code:

void main() {
unsigned char MyError, Temp;
CMCON = 7; // Disable Comparators
TRISB = 0b00000010;
UART1_Init(9600);
Delay_ms(100);
UART1_Write_Text("Testing UART! ");
newline();
do {
UART1_Write_Text("Type in a Number: ");
while(!UART1_Data_Ready());
Temp = UART1_Read();
newline();
UART1_Write_Text("You entered: ");
UART1_Write(Temp);
newline();
} while(1); } // End main()

This code is correct. I have copied this code from link:https://embedded-lab.com/blog/?p=1296

but this code shows nothing on terminal!

 

[embRTS]

Any other Code you tried like LED blinking and all other using Mikro C like i wanted to know that whether the hex file are created Actually i am thinking other side that whether MikroC is working or not,

or else do one thing there is a library in Mplab_IDE
You can use that also first check that thing also

Meanwhile also define newline() function in your code

 

[jayanth.devarayanadurga]

Try this code for testing UART.

Fosc = 4 MHz and baudrate = 9600 bps

---

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void newline(){
    UART1_Write(0x0D);
    UART1_Write(0x0A);
}
 
void main(){
 
     unsigned char MyError, number[24], i;
     CMCON = 7; // Disable Comparators
     
     TRISA = 0xFF;
     PORTA = 0x00;
     TRISB = 0x02;
     PORTB = 0x00;
 
     UART1_Init(9600);
     Delay_ms(100);
 
     UART1_Write_Text("Testing UART!");
     newline();
 
     while(1){
       UART1_Write_Text("Type in a Number: ");
       while(!UART1_Data_Ready());
       while(number[i] != 0x0D)
            number[i++] = UART1_Read();
       number[i] = '\0';
       newline();
       UART1_Write_Text("You entered: ");
       UART1_Write_Text(number);
       newline();
     }
}

---

 

[Mrunal Ahirrao]

Any other Code you tried like LED blinking and all other using Mikro C like i wanted to know that whether the hex file are created Actually i am thinking other side that whether MikroC is working or not,

or else do one thing there is a library in Mplab_IDE
You can use that also first check that thing also

Meanwhile also define newline() function in your code

I have successfully completed many parallel communications projects and it works well! So no problem of MikroC.

- - - Updated - - -

Thanks jayanth.devarayanadurga I will try this code and tell you about it.

 

[Mrunal Ahirrao]

Try this code for testing UART.

Fosc = 4 MHz and baudrate = 9600 bps

---

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void newline(){
    UART1_Write(0x0D);
    UART1_Write(0x0A);
}
 
void main(){
 
     unsigned char MyError, number[24], i;
     CMCON = 7; // Disable Comparators
     
     TRISA = 0xFF;
     PORTA = 0x00;
     TRISB = 0x02;
     PORTB = 0x00;
 
     UART1_Init(9600);
     Delay_ms(100);
 
     UART1_Write_Text("Testing UART!");
     newline();
 
     while(1){
       UART1_Write_Text("Type in a Number: ");
       while(!UART1_Data_Ready());
       while(number[i] != 0x0D)
            number[i++] = UART1_Read();
       number[i] = '\0';
       newline();
       UART1_Write_Text("You entered: ");
       UART1_Write_Text(number);
       newline();
     }
}

---

Thanks for the code. But nothing is displayed on PC.

 

[jayanth.devarayanadurga]

The last character should be 0x0D else it will not come out of UART read loop. Use below code. It reads 12 characters.

---

Code C - [expand]
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while(i < 12)
            number[i++] = UART1_Read();
       number[i] = '\0';

---

 

[Mrunal Ahirrao]

The last character should be 0x0D else it will not come out of UART read loop. Use below code. It reads 12 characters.

---

Code C - [expand]
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while(i < 12)
            number[i++] = UART1_Read();
       number[i] = '\0';

---

But it didn't even displayed the "Testing UART" line or "Enter number".

 

[embRTS]

Just use a simple for loop
it might help you as EM-18 module ID- cards are of 12 bytes
so apply the following loop

unsigned char i,unsigned char card[12];
for(i=0;i<12;i++)
{
card[i] = Receive Function for UART();             // receive card value byte by byte ;;12 Byte
}

Try this

 

[jayanth.devarayanadurga]

It works fine for me. Check your hardware.

 

[Mrunal Ahirrao]

It works fine for me. Check your hardware.

thanks. Your code is very robust I will try it and tell you.In second image why 10K resistors are used?

- - - Updated - - -

Just use a simple for loop
it might help you as EM-18 module ID- cards are of 12 bytes
so apply the following loop

unsigned char i,unsigned char card[12];
for(i=0;i<12;i++)
{
card[i] = Receive Function for UART();             // receive card value byte by byte ;;12 Byte
}

Try this

thanks. I will try it

 

[jayanth.devarayanadurga]

Instead of pullup on UART lines use pull down resistors.

 

[Mrunal Ahirrao]

hi again! Now its showing "testing UART" "Type in number" but I am not getting Echo back!

 

[jayanth.devarayanadurga]

Are you testing in Proteus or hardware?

 

[Mrunal Ahirrao]

On hardware. And I have found the problem.There is no stop bit sent from PIC to PC and from PC to PIC! and when I pull the receiving lines high then again the RB1/RX of PIC is gone high and PIC ready to receive from PC or else If i dont pull then it would never respond to data from PC! and same with PC. When I pull high the transmit of MAX232 then it stops transmitting data to PC and it will now respond to data from PC.

 

[jayanth.devarayanadurga]

Pull down only the Rx and Tx lines between MCU and MAX232. Don't pullup or pull down any other lines. Check bu connecting Rx and Tx pins to Oscilloscope. The bits are ok. Use rev2 file.

 

[Mrunal Ahirrao]

Its working now I replaced max232, and its working correctly. Now I am successful in UART communication! Now I will try to interface RFID reader with PIC16F628A. Thanx all of u!