I got all hot and bothered after reading an Instructable on mag stripe reading so I ordered up a Panasonic #ZU-M2121S451 from All Electronics and got to work. There is already source code available in a couple of places to interface with this little bugger but it isn't as step-by-step as I'd like. I threw up a picture and a description of the pins. Check it out if you like: http://cal.freeshell.org/projects/
The code is a very slightly modified version of Stephen King's that can be found here: Web Page Under Construction
I guess the idea is to try and make this a little easier for non-electrical guys like myself. Data sheets give me fits and Stephen wasn't that descriptive. You need to read his comments to even find out that he plugged the Clock pin into Digital 3.
I love cheap hacks, so I sent off for one of these mag card readers and I will be following along. Don't know what I'll use it for, maybe for manual external operation of the garage door
Well I received the mag card reader yesterday from All Electronics and hooked it up and loaded the code and it works great. What a great low cost cool item. Makes it easy to add some security to any project you may have.
Thanks for the tip, what a great community we have!
Does anyone know how to change the data and clock pin from 2 and 3 to something else?
The data pin is listed as 2 below but I can find where it lists that the clock pin is pin 3 on the arduino anywhere in the code. When I change the data pin to 5 lets say and leave the clock on 3, it doesn't return proper data when I swipe a card. Also tried putting data on Pin 5 and clock on Pin 6 in case there was a +1 command I was missing but still nothing.
It would be ideal for me for the pins to be changed to:
Data = Pin 5
Clock = Pin 6
Card Present = Pin 7
The program is using the two user interrupt pins 2 & 3 to decode the data. The pins assignments are assumed (and fixed) by the following lines:
attachInterrupt(0, changeBit, CHANGE); // Interrupt 0 is 'hardwired' to pin 2.
attachInterrupt(1, writeBit, FALLING); // Interrupt 1 is 'hardwired' to pin 3.
The use of the two user interrupts is essitianl to this program and can not be changed to other pins. Changing the data and clock lines to other I/O pins would require a complete redesign and rewrite of the program not to utilize the user interrupts, and might not be possible or practical to do without using interrupts.
So that's why. Is there any way to add another 2 interrupt pins to the Arduino. If not, how about connecting a second Arduino so you can use 2 pairs of interrupt pins in the same program (mag card reader), would that be difficult to configure/program for the magstripe reader?
I don't belive it's possible to attach additonal user interrupt pins, but then again all I know it the information provided by the Arduino site.
It would be possible to use two Arduino chips where one is just used to scan the card reader using the interrupt pins and send information to another board via serial link.
I am pretty sure I've read that the ATmegas used for the arduino support pinchange interrupts on all I/O pins.
So the limiting of just pins 2 & 3 for user interrupts is just a Arduino library restriction/design thing? Seems like if so it would be easy to change it to allow more pin choices?
This is a brushless cd rom motor which I use because I can read the hall effect sensors and use the whole setup as rotary encoder. More info here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1219763383
There are 3 hall effect sensors, the signal from which is passed through LM339N comparator and three pins go into digital pins 8, 9, and 10 and an interrupt handler records the state of the comparator. Later in the loop it's analysed for direction.
There's the traditional interrupt on pins 2 & 3, where a specific interrupt handler is called for each pin. Some ATmegas have a "pinchange" interrupt, where an interrupt handler is called if any pin on that port (port is a group of 8 pins) changes. It is up to the programmer to figure out which pin actually change and act accordingly.
Ok I will have to play around with it. Don't have much knowledge about programming the Arduino. I wanted to use 4 interrupt pins instead of 2 basically.
Also I rearranged the program so it decodes backwards swipes (reverse reads), I was wondering how I can put both these codes into one.
Original (Forward Swipes Only)
/*
* Magnetic Stripe Reader
* by Stephan King http://www.kingsdesign.com
*
* Reads a magnetic stripe.
*
*/
int cld1Pin = 5; // Card status pin
int rdtPin = 2; // Data pin
int reading = 0; // Reading status
volatile int buffer[400]; // Buffer for data
volatile int i = 0; // Buffer counter
volatile int bit = 0; // global bit
char cardData[40]; // holds card info
int charCount = 0; // counter for info
int DEBUG = 0;
void setup() {
Serial.begin(9600);
// The interrupts are key to reliable
// reading of the clock and data feed
attachInterrupt(0, changeBit, CHANGE);
attachInterrupt(1, writeBit, FALLING);
}
void loop(){
// Active when card present
while(digitalRead(cld1Pin) == LOW){
reading = 1;
}
// Active when read is complete
// Reset the buffer
if(reading == 1) {
if (DEBUG == 1) {
printBuffer();
}
decode();
reading = 0;
i = 0;
int l;
for (l = 0; l < 40; l = l + 1) {
cardData[l] = '\n';
}
charCount = 0;
}
}
// Flips the global bit
void changeBit(){
if (bit == 0) {
bit = 1;
} else {
bit = 0;
}
}
// Writes the bit to the buffer
void writeBit(){
buffer[i] = bit;
i++;
}
// prints the buffer
void printBuffer(){
int j;
for (j = 0; j < 200; j = j + 1) {
Serial.println(buffer[j]);
}
}
int getStartSentinal(){
int j;
int queue[5];
int sentinal = 0;
for (j = 0; j < 400; j = j + 1) {
queue[4] = queue[3];
queue[3] = queue[2];
queue[2] = queue[1];
queue[1] = queue[0];
queue[0] = buffer[j];
if (DEBUG == 1) {
Serial.print(queue[0]);
Serial.print(queue[1]);
Serial.print(queue[2]);
Serial.print(queue[3]);
Serial.println(queue[4]);
}
if (queue[0] == 0 & queue[1] == 1 & queue[2] == 0 & queue[3] == 1 & queue[4] == 1) {
sentinal = j - 4;
break;
}
}
if (DEBUG == 1) {
Serial.print("sentinal:");
Serial.println(sentinal);
Serial.println("");
}
return sentinal;
}
void decode() {
int sentinal = getStartSentinal();
int j;
int i = 0;
int k = 0;
int thisByte[5];
for (j = sentinal; j < 400 - sentinal; j = j + 1) {
thisByte[i] = buffer[j];
i++;
if (i % 5 == 0) {
i = 0;
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0) {
break;
}
printMyByte(thisByte);
}
}
Serial.print("Stripe_Data:");
for (k = 0; k < charCount; k = k + 1) {
Serial.print(cardData[k]);
}
Serial.println("");
}
void printMyByte(int thisByte[]) {
int i;
for (i = 0; i < 5; i = i + 1) {
if (DEBUG == 1) {
Serial.print(thisByte[i]);
}
}
if (DEBUG == 1) {
Serial.print("\t");
Serial.print(decodeByte(thisByte));
Serial.println("");
}
cardData[charCount] = decodeByte(thisByte);
charCount ++;
}
char decodeByte(int thisByte[]) {
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 1){
return '0';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0){
return '1';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0){
return '2';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 1){
return '3';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 0){
return '4';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 1){
return '5';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 1){
return '6';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 0){
return '7';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 0){
return '8';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 1){
return '9';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 1){
return ':';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 0){
return ';';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 1){
return '<';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 0){
return '=';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 0){
return '>';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 1){
return '?';
}
}
Reverse Read
/*
* Magnetic Stripe Reader
* by Stephan King http://www.kingsdesign.com
*
* Reads a magnetic stripe.
*
*/
int cld1Pin = 5; // Card status pin
int rdtPin = 2; // Data pin
int reading = 0; // Reading status
volatile int buffer[400]; // Buffer for data
volatile int i = 0; // Buffer counter
volatile int bit = 0; // global bit
char cardData[40]; // holds card info
int charCount = 0; // counter for info
int DEBUG = 0;
void setup() {
Serial.begin(9600);
// The interrupts are key to reliable
// reading of the clock and data feed
attachInterrupt(0, changeBit, CHANGE);
attachInterrupt(1, writeBit, FALLING);
}
void loop(){
// Active when card present
while(digitalRead(cld1Pin) == LOW){
reading = 1;
}
// Active when read is complete
// Reset the buffer
if(reading == 1) {
if (DEBUG == 1) {
printBuffer();
}
decode();
reading = 0;
i = 0;
int l;
for (l = 0; l < 40; l = l + 1) {
cardData[l] = '\n';
}
charCount = 0;
}
}
// Flips the global bit
void changeBit(){
if (bit == 0) {
bit = 1;
} else {
bit = 0;
}
}
// Writes the bit to the buffer
void writeBit(){
buffer[i] = bit;
i++;
}
// prints the buffer
void printBuffer(){
int j;
for (j = 0; j < 200; j = j + 1) {
Serial.println(buffer[j]);
}
}
int getStartSentinal(){
int j;
int queue[5];
int sentinal = 0;
for (j = 0; j < 400; j = j + 1) {
queue[4] = queue[3];
queue[3] = queue[2];
queue[2] = queue[1];
queue[1] = queue[0];
queue[0] = buffer[j];
if (DEBUG == 1) {
Serial.print(queue[0]);
Serial.print(queue[1]);
Serial.print(queue[2]);
Serial.print(queue[3]);
Serial.println(queue[4]);
}
if (queue[0] == 1 & queue[1] == 1 & queue[2] == 1 & queue[3] == 1 & queue[4] == 1) { //start sentinal for reverse read
sentinal = j - 4;
break;
}
}
if (DEBUG == 1) {
Serial.print("sentinal:");
Serial.println(sentinal);
Serial.println("");
}
return sentinal;
}
void decode() {
int sentinal = getStartSentinal();
int j;
int i = 0;
int k = 0;
int thisByte[5];
for (j = sentinal; j < 400 - sentinal; j = j + 1) {
thisByte[i] = buffer[j];
i++;
if (i % 5 == 0) {
i = 0;
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0) {
break;
}
printMyByte(thisByte);
}
}
Serial.print("Stripe_Data:");
for (k = 0; k < charCount; k = k + 1) {
Serial.print(cardData[k]);
}
Serial.println("");
}
void printMyByte(int thisByte[]) {
int i;
for (i = 0; i < 5; i = i + 1) {
if (DEBUG == 1) {
Serial.print(thisByte[i]);
}
}
if (DEBUG == 1) {
Serial.print("\t");
Serial.print(decodeByte(thisByte));
Serial.println("");
}
cardData[charCount] = decodeByte(thisByte);
charCount ++;
}
char decodeByte(int thisByte[]) { //reversed orders
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0){
return '0';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 1){
return '1';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 0){
return '2';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 1){
return '3';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 0){
return '4';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 1){
return '5';
}
if (thisByte[0] == 1 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 0){
return '6';
}
if (thisByte[0] == 0 & thisByte[1] == 0 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 1){
return '7';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 0){
return '8';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 0 & thisByte[4] == 1){
return '9';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 0){
return ':';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 0 & thisByte[3] == 1 & thisByte[4] == 1){
return ';';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 0){
return '<';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 0 & thisByte[4] == 1){
return '=';
}
if (thisByte[0] == 0 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 0){
return '>';
}
if (thisByte[0] == 1 & thisByte[1] == 1 & thisByte[2] == 1 & thisByte[3] == 1 & thisByte[4] == 1){
return '?';
}
}
The mag cards start with a bunch of 00000000's and then 11010 if it's a forward read or 11111 if its a reverse read so I guess the program needs to be told that if it starts with 11010 use normal character conversion and if it starts with 11111, reverse it. I was a bit confused why the line
Save a variable that indicates whether you found the forward or the reverse sentinel. Keep accumulating the rest of the numbers that come in from the card. After all the numbers have been collected, do the following, which I present in pseudo-code:
if we found the forward sentinel*
print the numbers in order*
else*
print the numbers in reverse order*
endif*
You might have to reverse the bits for each number if you are collecting them after the reverse sentinel. I don't know enough about the specs for that card reader to tell you that one way or the other. Check its data sheet.
Cool project, makes a lot of sense to allow swipes both ways. I often wish all card readers were like that. Let us know what you end up with.
You can't, this surplus item is a reader only, no writing capability. What you do is go into your desk draw and find all those old expired credit cards, driver license, etc and find out what numbers they have written on them by reading them with a simple sketch and use those in your final program sketch to allow access to only those numbers. I found at least have a dozen that read fine. You don't even have to use all the numbers encoded on a card, perhaps just the first 8 characters for a match, it is all under your program control.
