digitalpowers
Newbie level 2
So I have seen this topic covered several times before but no one really seems to finish with a lot of information. Let me give you some background on what I am trying to do and see if someone can help me.
I am cheep, so I would love to build my own access control system using HID Card readers that output in Wiegand, they are easy to find on ebay for cheep. Now the problem comes into when you look into the Wiegand protocol adn realize that it uses 50 micro second pulses to encode the data. Now that is too fast for my paralell port to read even in an infinite loop (not pritty code). So I got smart (i wish) and decided to buy a daq card (NIDAQ 6520). I got it cheep as well (thank you ebay). Unfortunately what I didnt see was that that card reads 12v pulses as high not 5v pulses as high. Unfortunately my reader outputs 5v for high. So now I have come to the point of either starting from scratch, ie comeing up with a new system to read wiegand, or figuring out how to pull the data lines high enough without pulling the low up to high. I tried a transistor amplifier but that pulls the low data signal up above the 4v it has to stay below to be considered a low pulse.
Anyways, I am not exactly sure what I want to do about this but if anyone has any ideas that would be great. And remember cheeper is better.
Thanks.
I am cheep, so I would love to build my own access control system using HID Card readers that output in Wiegand, they are easy to find on ebay for cheep. Now the problem comes into when you look into the Wiegand protocol adn realize that it uses 50 micro second pulses to encode the data. Now that is too fast for my paralell port to read even in an infinite loop (not pritty code). So I got smart (i wish) and decided to buy a daq card (NIDAQ 6520). I got it cheep as well (thank you ebay). Unfortunately what I didnt see was that that card reads 12v pulses as high not 5v pulses as high. Unfortunately my reader outputs 5v for high. So now I have come to the point of either starting from scratch, ie comeing up with a new system to read wiegand, or figuring out how to pull the data lines high enough without pulling the low up to high. I tried a transistor amplifier but that pulls the low data signal up above the 4v it has to stay below to be considered a low pulse.
Anyways, I am not exactly sure what I want to do about this but if anyone has any ideas that would be great. And remember cheeper is better.
Thanks.