Proxmark3 community

renko

Member

Registered: 2015-01-30

Posts: 8

Kantech XSF

I am re-posting this - I may have been in the wrong forum.

I was hoping that someone could offer some advice.

I watched Fran Brown's (Bishop Fox) presentation given at Blackhat and built one of his long range (he calls them weaponized) readers for 125mHz cards. It was based on an Kantech 5375 reader with Ardunio chip built on a board of his design that you can download. The setup uses and LCD screen and micro SD card to record the facility code and card number along with the Hex code that can be put directly into the Proxmark to clone a new card. It worked perfectly, recording one of may cards at about 2 1/2 feet.

I have been interested in the Kantech XSF cards and bought a used Kantech p600 long range reader in an attempt to repeat the success with XSF cards.  The antenna was damaged on the unit,  but I managed to fix that and when powered just by itself, using a battery pack, it would read an XSF card from about 2 feet away or a little better (it beeped).

When I built a new Ardunio board and installed it along with an LCD, the reader worked but only when the card was placed on the antenna. No range at all. It did read my own card correctly giving the FC and card number correctly. When powered by itself separate from the Ardunio board, it again read my card from a distance.

I should add that the  P600 reader is powered from the board that contains the Ardunio chip as is the LCD screen. All power from the battery pack goes in one end of the Arduino board and comes out the other end powering the LCD screen and the Kantech long range reader.  The Kantech reader has  DATA 0 and DATA 1 ports that plug into the Ardunio chip that processes what it reads and spits it out to the LCD screen and micro SD card.

Brown noted on his website that if you did not have a "common ground" you got "funky" results. I am not sure what this means, I am certainly getting almost no result.

I have tried powering the board and the reader from a single split wire (negative) from the battery pack but got the same result. The positive was plugged into the Arduino board.

I would appreciate any suggestions from someone who  understands this better than I do.

carl55

Contributor

From: Arizona USA

Registered: 2010-07-04

Posts: 175

Re: Kantech XSF

Renko,
You appear to be experiencing a classic power problem. From all indications it appears as though your power source is not adequate to handle your systems total electrical load.

The datasheet for the P600 reader states that the maximum current draw is 1.5 amps at 12Vdc. That is about 700ma more than the HID Maxiprox reader that was being used in the Bishop Fox demo. Depending on the particular AA batteries that you are using, that amount of current is more than they were typically designed to handle. When you exceed the current capability of the batteries, the output voltage will drop and the operation of the reader will be compromised. When the Arduino circuit is included as part of the electrical load the problem is aggrevated.

You need to measure the voltage at the reader input when all of the electrical loads are energized. I suspect that you will find that the reader voltage is below the 12Vdc minimum that it requires for proper operation.
In order to get the necessary current to flow to the reader you need to ensure that all elements in the circuit are able to handle the required load. That means that the battery, the circuit board traces, power switch, and the wires to the reader are all adequately rated for the total electrical load.

Regarding your circuit grounding question ...  Yes, you need to ensure that you have a good "common ground" connection between all of the circuit components. That means that the negative (-) terminal of the battery, the Vdd/Gnd pins on the Arduino, and the Vdd/Gnd connection on the P600 need to be physically connected together.

renko

Member

Registered: 2015-01-30

Posts: 8

Re: Kantech XSF

Thank you carl55 for the information. I didn't check to see if the P600 draws more current than the one in the Bishop Fox presentation. I am now wondering about the wiring and the fact that I noticed one of the AA batteries was quite warm and leaking when replaced. Makes sense now from what you have told me. Should have been bright enough to pick that up - but clearly wasn't.

Besides changing the power supply, I guess the only additional ground I need to ensure is connected is the VDD/GND on the Ardunio, since the (-) terminal on the battery is now connected both to the Ardunio input on the Bishop Fox board and a second wire from the same terminal to the P600.

Thanks again for the education - at least now I have some idea of what to try to fix.

renko

Member

Registered: 2015-01-30

Posts: 8

Re: Kantech XSF

carl55

I used a bench top power supply and dialed up 12 v at 1.5 amps and plugged it into the Arduino and the P600 and tried my card. It read the card at just under 3 ft, a big improvement over only being able to read the card by laying it on the antenna.

You were right on with your comment a "classic power problem." Thanks again for your help it is much appreciated.