Arduino & ID-12 RFID reader not reading?

Development Boards Arduino
1

Hi all,

I’m having a bit of an issue with an ID-12 RFID reader not working, and I was wondering if I could possibly get some assistance?

As part of an automatic train detection system on my model railroad, I’ve got an ID-12 RFID reader mounted above the tracks, hooked back to an Arduino Duemilanove (via a Sparkfun breakout board) as per the diagram in step 2 of this tutorial: http://www.instructables.com/id/Reading … /?ALLSTEPS. D0 goes back to pin 9 of the Duemilanove, which is configured in the software (below) as the RX pin of a SoftwareSerial object. (The hardware serial will be used for an XBee module for communication to another system). The other pin of the SoftwareSerial, Pin 7, is not connected to anything at all.

Below is the code for the test program:

#include <SoftwareSerial.h>
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>

SoftwareSerial rfidSerial(9, 7); // RX, TX
char val = 0;
LiquidCrystal_I2C lcdScreen(0x27,2,1,0,4,5,6,7); //LCD Display

void setup() {
  // put your setup code here, to run once:
  rfidSerial.begin(9600);
  Serial.begin(9600);
}

void loop () {
  byte i = 0;
  byte val = 0;
  byte code[6];
  byte checksum = 0;
  byte bytesread = 0;
  byte tempbyte = 0;

  if(Serial.available() > 0) {
    if((val = Serial.read()) == 2) {                  // check for header
      bytesread = 0;
      while (bytesread < 12) {                        // read 10 digit code + 2 digit checksum
        if(Serial.available() > 0) {
          val = Serial.read();
          if((val == 0x0D)||(val == 0x0A)||(val == 0x03)||(val == 0x02)) { // if header or stop bytes before the 10 digit reading
            break;                                    // stop reading
          }

          // Do Ascii/Hex conversion:
          if ((val >= '0') && (val <= '9')) {
            val = val - '0';
          } else if ((val >= 'A') && (val <= 'F')) {
            val = 10 + val - 'A';
          }

          // Every two hex-digits, add byte to code:
          if (bytesread & 1 == 1) {
            // make some space for this hex-digit by
            // shifting the previous hex-digit with 4 bits to the left:
            code[bytesread >> 1] = (val | (tempbyte << 4));

            if (bytesread >> 1 != 5) {                // If we're at the checksum byte,
              checksum ^= code[bytesread >> 1];       // Calculate the checksum... (XOR)
            };
          } else {
            tempbyte = val;                           // Store the first hex digit first...
          };

          bytesread++;                                // ready to read next digit
        }
      }

      // Output to LCD:

      if (bytesread == 12) {                          // if 12 digit read is complete
        lcdScreen.clear();
        lcdScreen.home();
        lcdScreen.print("5-byte code: ");
        for (i=0; i<5; i++) {
          if (code[i] < 16) lcdScreen.print("0");
          lcdScreen.print(code[i], HEX);
          lcdScreen.print(" ");
        }
        lcdScreen.println();

        lcdScreen.print("Checksum: ");
        lcdScreen.print(code[5], HEX);
        lcdScreen.println(code[5] == checksum ? " -- passed." : " -- error.");
        lcdScreen.println();
      }

      bytesread = 0;
    }
  }
}

I had previously tested the ID-12 with the above code, but with the output to the serial port instead (i.e. replace ‘lcdScreen’ with ‘Serial’ in the body of the program) and it was able to read the RFID tags. However, when I tried it on the model railroad, there was no response, even when I touched the RFID tag right on top of the reader. I also tried adapting the above code to just show a line saying ‘RFID Tag Read’, also with no luck.

One thing that’s just struck me, as I write this, is that the Duemilanove is powering quite a few other sensors from it’s 5V output as well:

  • 3 light dependant-resistors

  • 2 HR-S04 ultrasonic modules

As such, would providing the ID-12 with its own 5V power supply (with a common ground to the Arduino) possibly fix this issue?

Cheers,

Tbdanny

2

Hi all,

I’ve just tried testing with my laptop and the original code, which was supposed to output the tag’s ID to the serial monitor on the laptop. No luck. I passed a spare RFID tag under the reader several times, and got nothing.

I also tried powering the ID-12 from its own 4.5v DC power supply, in case the Arduino wasn’t providing enough current for the RFID reader. There is a common ground connection between the power supply to the RFID reader and the Arduino. Again, this yielded no results.

The only other difference is that during the original testing, I used pin 6 as the RX and 7 as the TX on the Arduino, whereas in this implementation, I’m currently using pin 9 as the RX and 7 as the TX. In both cases, pin 7 was disconnected. Given that I’m using softwareserial, I didn’t think this would make a difference. Would it?

Cheers,

Tbdanny