Mag Card Reader

[aetosat]

Dear Mrs. Melanie,

First of all I would like to give you congratulations for your wonderful style in
teaching people how to learn and how to solve different problems regarding programming of pic microcontrollers and for all those programming samples ,so useful ,for all the guys arround,experts or newbies.
I would like to ask an advice about a card reader build by a guy ,based on your project (magcard).He used a magtek reader and the problem he had ,was on reader's card detection.Seemed that you and Mr. Bruce R. gave him some advice at that time, to put a capacitor somewhere on the circuit.Can you tell me where I can find that post!?I'm working on something similar,only that I start with the very beggining:
I build the reader myself (the hardware and software),using a mag-tek chip decoder for tracks 1 & 2,decoder circuit + magnetic head ( I will try different types) ,actually will work for track 2 for the beggining,and I will like to perform different tests to bring that project to a portable magnetic
card reader!
There are some companies arround claiming that, they sale the smallest magnetic card readers in the world!Well,I doubt about it!
Just for the work of art I will try to see ,how far it can go,and how small can become the real "smallest portable magnetic card reader" !
I'm wondering how difficult it will be and how long time will take to write a program for all the three tracks of the magcard.
I'm using an ICD interface to debug my programs with MicroCode Studio Plus and perhaps it will be good to provide the pcb (which I designed myself) and the schematic + components, here on this forum for people which will be interested to use it!
Thank you for taking the time to read my message and for that wonderful piece of software (magcard.txt) ,the most interesting I found all over the net!
For the link to AN727 datasheet from Microchip as well!

My Best Regards!
Aetosat

[Melanie]

Dear Mrs. Melanie - Ohhhh... don't marry me off yet... I'm still a Miss Melanie! Thank you for the compliments.

I don't recall giving advice about putting a Capacitor anywhere... perhaps it was Bruce. The Card-Detect is usually accomplished by either a photocell or a microswitch. Some cheap readers have the sensor positioned in front of the Read-Head so a card is detected as soon as it is inserted into the slot, but as it is swiped it is still travelling past the Read-Head as it clears the sensor therefore giving too early a warning that the card has been removed, so spoiling the read. A Capacitor could then be inserted to delay the card-detect signal... perhaps that was the reason, otherwise I just can't remember what it was for.

Anyhow, if you're only at the start of your project, I wouldn't worry about it until you meet any problem.

If you are going to read more than one track at the same time, then you will need either more PICs - one for each track, or a different PIC, as I recall (remember this was THREE YEARS AGO in 2002) the 16F84 pretty much maxed out on that RAM Buffer, and the 16F628 was only a bit better. You should be able to do it in one PIC, but will need to chose one with a lot more RAM and depending on how many tracks, you might need a speed increase beyond 4MHz.

Best wishes on your project in trying to make the world's smallest reader - Have fun.

[DynamoBen]

I too am using the MagCard code. I'm almost to the end of my project. I'm using a standard card reader (not serial), I2C memory to store account numbers, and RS-485 interface.

The only difference in my project is I'm stripping out only the account data and storing it. For security reasons I'm not collecting the balance of the information. (expiration date, pin hash)

I'm with Melanie in that you should start writing some code and experiment a little. I have modified her code very little and her code worked right away.