Post by thread:Magnetic Card Reader Project advice sought

I am attempting to do the following project. If anyone has done a similar project or part, thereof, I would appreciate any advice or suggestions you may have. Specs ----- 1. Sense presence of card using some sensor. Tell 16c84. 2. Suck card into slot using stepper motor controlled via 16c84. 3. Read Magnetic card strip. All 3 tracks. (not sure whether to do in ttl or rs232). 4. Feed data to pic 16c84. 5. Store data in non-volatile memory chip - 500K to 2Mbytes. 6. Eject card using stepper motor controlled via 16c84. + do not activate sensor on way out (or ignore it). Questions --------- 0. How difficult/feasible is this project? 1. Which parts to use and where to get them: stepper motor, sensor, memory chip, card reader (or head). 2. Which format to feed data from reader to 16c84. ttl or rs232. advantages/disadvantages. 3. Whether it is possible to feed so much data to 16c84. ie. all 3 tracks = 350 characters. 4. Whether it is possible to store 500K to 2Mbytes on a memory chip. 4a. Which chip? (ie. EEPROM, NV-SRAM? + manufacturer) 4b. Do I need to use i2c protocol to make it serial? 5. Can 16c84 write to memory chip using i2c protocol? 6. What is advantage of using 16c84 rather than other PIC m/c. (apart from EEPROM advantage?) About me -------- This is my second PIC project, so I thought I'll just jump in the deep end. My first project from Maplins (GT04 project), didn't work. (Got some smoke coming from a transistor!) Please explain everything in detail (especially references to sites/components/code etc.), as I'm new to PIC. Understand digital electronics as have Computer Degree, but new to Analogue electronics. Thankyou for your help. John. spam_OUTujsecTakeThisOuTwmin.ac.uk

At 11:03 AM 3/24/98, you wrote: >I am attempting to do the following project. If anyone has done a >similar project or part, thereof, I would appreciate any advice or >suggestions you may have. > >Specs >----- >1. Sense presence of card using some sensor. Tell 16c84. > >2. Suck card into slot using stepper motor controlled via 16c84. > >3. Read Magnetic card strip. All 3 tracks. (not sure whether to > do in ttl or rs232). I don't know anything about the format in which the data is stored on the strip, but I would immagine that it is independent of the rate at which the card is swiped past the magnetic head. I would think this because, if this were not the case and the card had to go past at a specific rate, then we couldn't have manually swiped card readers, and we do have them. The point is this: you may not need to use a stepper motor if the rate is not critical. You could simply use a geared-down DC motor. Also, unless the data comes off the card in something similar to RS232 format, I don't see any reason to try to convert it to RS232, I would just send the amplified/clipped pulses to the PIC. There is certainly no reason not to use TTL levels, since these are the only thing that a PIC can accept directly (without some conversion circuit). Good luck, Sean +--------------------------------+ | Sean Breheny | | Amateur Radio Callsign: KA3YXM | | Electrical Engineering Student | +--------------------------------+ Fight injustice, please look at http://homepages.enterprise.net/toolan/joanandrews/ Personal page: http://www.people.cornell.edu/pages/shb7 .....shb7KILLspam@spam@cornell.edu Phone(USA): (607) 253-0315

>> >>3. Read Magnetic card strip. All 3 tracks. (not sure whether to >> do in ttl or rs232). > >I don't know anything about the format in which the data is stored on the >strip, but I would immagine that it is independent of the rate at which the >card is swiped past the magnetic head. I would think this because, if this I was once going to tackle a similar problem, and I have several text files explaining the data encoding. I however do not have them here at work. I will find them tonight and send them your way. Brad ______________________________________________________________________ Brad Stockdale GreenePA.Net is a GreenePA Support Team service of Within supportKILLspamgreenepa.net Technology, Inc. 852-2599

Would you mind sending the info to me also. I've got a card reader project comming up for a voluteer organization. Thanks, Arvid .....arvidjKILLspam.....visi.com {Quote hidden}> I was once going to tackle a similar problem, and I have several text files > explaining the data encoding. I however do not have them here at work. I > will find them tonight and send them your way. > > Brad > > ______________________________________________________________________ > > Brad Stockdale GreenePA.Net is a > GreenePA Support Team service of Within > EraseMEsupportspam_OUTTakeThisOuTgreenepa.net Technology, Inc. > 852-2599 >

At 05:02 PM 3/24/98 -0500, you wrote: >John, > > A couple of months ago I played around with a magnetic card reader. I >got all the necessary info at this site: > http://falcon.arts.cornell.edu/~dnegro/cardreader.html > >Good luck, > >Aaron > Wow, this is pretty amazing, that is the second cornell URL on the piclist in tha last few days. Hmmm, more people here interested in electronics than I thought, and in the arts school, no less! Sean +--------------------------------+ | Sean Breheny | | Amateur Radio Callsign: KA3YXM | | Electrical Engineering Student | +--------------------------------+ Fight injustice, please look at http://homepages.enterprise.net/toolan/joanandrews/ Personal page: http://www.people.cornell.edu/pages/shb7 shb7spam_OUTcornell.edu Phone(USA): (607) 253-0315

> Subject: Magnetic Card Reader Project advice sought > Date: Tue, 24 Mar 1998 11:03:15 0 > From: John Smith <@spam@ujsecKILLspamWESTMINSTER.AC.UK> > > I am attempting to do the following project. If anyone has done a > similar project or part, thereof, I would appreciate any advice or > suggestions you may have. * What do the parts have to cost in total? > > > Specs > ----- > 1. Sense presence of card using some sensor. Tell 16c84. *Use an optical sensor (interrupt with TTL output) > > > 2. Suck card into slot using stepper motor controlled via 16c84. * Steppers come in many sizes. A small one with a low cost driver chip should work. Why use a stepper? Why not turn on a DC motor to pull the card through? > > > 3. Read Magnetic card strip. All 3 tracks. (not sure whether to > do in ttl or rs232). * I suggest TTL. Simpler and able to bridge a resonable distance. > > > 4. Feed data to pic 16c84. > > 5. Store data in non-volatile memory chip - 500K to 2Mbytes. * I am sure this is doable depending on your budget. > > > > 6. Eject card using stepper motor controlled via 16c84. + do not > activate sensor on way out (or ignore it). * Same motor as before > > > Questions > --------- > 0. How difficult/feasible is this project? * More of a mechanical challenge than a electronic one. > > > 1. Which parts to use and where to get them: > stepper motor, sensor, memory chip, card reader (or head). > > 2. Which format to feed data from reader to 16c84. ttl or rs232. > advantages/disadvantages. * TTL simpler, cheaper,adequate distance > > > 3. Whether it is possible to feed so much data to 16c84. > ie. all 3 tracks = 350 characters. * probably > > > 4. Whether it is possible to store 500K to 2Mbytes on a memory chip. > 4a. Which chip? (ie. EEPROM, NV-SRAM? + manufacturer) * Serial EEPROM is probably a good choice > 4b. Do I need to use i2c protocol to make it serial? * No > > > 5. Can 16c84 write to memory chip using i2c protocol? * Yes, recommend you use simpler serial protocol > > > 6. What is advantage of using 16c84 rather than other PIC m/c. > (apart from EEPROM advantage?) * Easy member of the PIC family to prototype with {Quote hidden}> > > About me > -------- > This is my second PIC project, so I thought I'll just jump in the deep > end. My first project from Maplins (GT04 project), didn't work. (Got > some smoke coming from a transistor!) > > Please explain everything in detail (especially references to > sites/components/code etc.), as I'm new to PIC. Understand > digital electronics as have Computer Degree, but new to Analogue > electronics. > > Thankyou for your help. > > John. > KILLspamujsecKILLspamwmin.ac.uk > > ------------------------------------------------------------------------ >

Sean Breheny wrote: > I don't know anything about the format in which the data is stored on > the strip, but I would immagine that it is independent of the rate at > which the card is swiped past the magnetic head. Well, not quite; it is supposed to be written accurately and to a particular specification. > ... we couldn't have manually swiped card readers, and we do have > them. Indeed we do, but they require software with a *very* wide capture range. Using a capstan drive simplifies the task tremendously and makes it far more reliable. > you may not need to use a stepper motor if the rate is not critical. You may not *want* to. Steppers make the travel jerky and you still need a flywheel! > You could simply use a geared-down DC motor. *If* it is cheaper. > Also, unless the data comes off the card in something similar to RS232 > format, I don't see any reason to try to convert it to RS232, This is DŽjˆ v! RS-232 is *not* a format, it is a voltage specification. > I would just send the amplified/clipped pulses to the PIC. There is > certainly no reason not to use TTL levels, since these are the only > thing that a PIC can accept directly .. and in fact, the only thing that "bare" card reader modules as you propose to use ready-built, give out. As was pointed out last round of this discussion, the exercise may be interesting, but unless you plan on production in the thousands, or greater, it's more economical to purchase the assembly complete with motor drive. The thing to do would be to sniff out who IBM, ICL and so on, buy them from. They don't necessarily do it all in-house. Cheers, Paul B.