Returning to the hardware prototyping after a bit of a hiatus, we started plugging away again at the intricacies of serial communication with the Lilypad.  Yesterday we got the XBees up and running again, so today we tackled the Lilypad + RFID reader, a combination that we had not gotten working before. 

We soon ran into what we thought was an insurmountable problem: the RFID reader communicates at 9600 bps, and the Arduino Lilypad with the Atmega 328 could only handle 19200.  However, we poked around online and discovered that the Lilypad issue was a software thing, not hardware, and the most recent version of the Arduino programming environment (arduino017) fixes the issue.  So now the Lilypad actually will communicate at 9600 when you tell it too, and we were successfully able to turn the onboard LED on and off by placing an RFID chip next to the reader.  We haven’t been able to read actual chip information yet, but the next step is to go and redo the XBee code at 9600 and then get the XBee to send the tag info out wirelessly.  Josh also put together a custom power circuit, since the Lilypad power supplies seemed to not be functioning properly.
Here’s the RFID reader code:

// RFID reader ID-12 for Arduino
// Based on code by BARRAGAN
// and code from HC Gilje - http://hcgilje.wordpress.com/resources/rfid_id12_tagreader/
// Modified for Arudino by djmatic
// Modified for ID-12 and checksum by Martijn The - http://www.martijnthe.nl/
//
// Use the drawings from HC Gilje to wire up the ID-12.
// Remark: disconnect the rx serial wire to the ID-12 when uploading the sketch
#define ledPin 13
byte pinState = 0;

void setup() {
Serial.begin(9600);                                 // connect to the serial port
pinMode(ledPin, OUTPUT);
}

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 == 0×0D)||(val == 0×0A)||(val == 0×03)||(val == 0×02)) { // 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 Serial:

if (bytesread == 12) {                          // if 12 digit read is complete
Serial.print(”5-byte code: “);
for (i=0; i<5; i++) {
if (code[i] < 16) Serial.print(”0″);
Serial.print(code[i], HEX);
Serial.print(” “);
}
toggle(13);
Serial.println();

Serial.print(”Checksum: “);
Serial.print(code[5], HEX);
Serial.println(code[5] == checksum ? ” — passed.” : ” — error.”);
Serial.println();
}

bytesread = 0;
}
}
}

void toggle(int pinNum) {
// set the LED pin using the pinState variable:
digitalWrite(pinNum, pinState);
// if pinState = 0, set it to 1, and vice versa:
pinState = !pinState;
}