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#1 2018-01-13 22:51:21

Registered: 2017-12-31
Posts: 19

LF Antenna 0 Volts [resolved]

PS@ 20180113_23:58: Thread on hold. Testing out and verifying latest Github-Updates regarding LF-antenna.


yesterday evening I was still trying to get the emulation/simulation of cards to work. Did one more hardnested attack before going to sleep, closed the Proxspace and went to bed.
This morning the Proxmark didnt respond to anything. I didnt change bootloader or firmware. Traced the error.

hw tune - makes the proxmark not respond enymore.
hw tune h - gives following result:
proxmark3> hw tune h

Measuring antenna characteristics, please wait...
# LF antenna:  0.00 V @   125.00 kHz
# LF antenna:  0.00 V @   134.00 kHz
# LF optimal:  0.00 V @ 12000.00 kHz
# HF antenna: 31.87 V @    13.56 MHz
# Your LF antenna is unusable.

hw tune l - makes proxmark not respond anymore.

I did measurements on the LF-antenna using a multimeter. The antenna has really low resistance, doesnt seem broken. The resistance is not absolutely zero, so I presume it is not short-circuited either. Made same measurements board-side on the connectors, seemed also fine.

My guess is the PM3 fails to supply the required power to the antenna for operational levels or maybe some chip is defective.
I would repair it myself, but Im not familiar with the layout, chips and blueprints (I repaired old motherboards and stuff, but the PM3 is just too expensive and fragile for me to try). I'm not even really sure what exactly the defect might be.

Anyone got an idea? Is it a case for warranty or think its repairable with some easy trick?

kindly regards, Skel

Reflashed the bootloader and firmware. At least HF-operations seem to work again.

basic setup:
Prox/RFID mark3 RFID instrument
bootrom: master/v3.0.1-249-g2d51da3-dirty-suspect 2018-01-13 18:25:57
os: master/v3.0.1-249-g2d51da3-dirty-suspect 2018-01-13 18:26:18
LF FPGA image built for 2s30vq100 on 2015/03/06 at 07:38:04
HF FPGA image built for 2s30vq100 on 2017/10/27 at 08:30:59

uC: AT91SAM7S512 Rev B
Embedded Processor: ARM7TDMI
Nonvolatile Program Memory Size: 512K bytes. Used: 199346 bytes (38%). Free: 324942 bytes (62%).
Second Nonvolatile Program Memory Size: None
Internal SRAM Size: 64K bytes
Architecture Identifier: AT91SAM7Sxx Series
Nonvolatile Program Memory Type: Embedded Flash Memory
proxmark3> hw ping
Ping successful

Last edited by Skeltek (2018-01-14 00:07:16)


#2 2018-01-13 23:33:04

Registered: 2017-12-31
Posts: 19

Re: LF Antenna 0 Volts [resolved]

Just tried around with things.
lf search seems to work somehow, even though the LF antenna is claimed as unusable

proxmark3> lf search
NOTE: some demods output possible binary
  if it finds something that looks like a tag
False Positives ARE possible

Checking for known tags:

EM410x pattern found:

EM TAG ID      : 3F001FEE7B

Possible de-scramble patterns
Unique TAG ID  : FC00F877DE
HoneyWell IdentKey {
DEZ 8          : 02092667
DEZ 10         : 0002092667
DEZ 5.5        : 00031.61051
DEZ 3.5A       : 063.61051
DEZ 3.5B       : 000.61051
DEZ 3.5C       : 031.61051
DEZ 14/IK2     : 00270585032315
DEZ 15/IK3     : 001082348042206
DEZ 20/ZK      : 15120000150807071314
Other          : 61051_031_02092667
Pattern Paxton : 1060383867 [0x3F342C7B]
Pattern 1      : 5226476 [0x4FBFEC]
Pattern Sebury : 61051 31 2092667  [0xEE7B 0x1F 0x1FEE7B]

Valid EM410x ID Found!


#3 2018-01-14 00:07:02

Registered: 2017-12-31
Posts: 19

Re: LF Antenna 0 Volts [resolved]

Okay, somehow I happened to fetch a github sourcecode version between new years and few days ago that had a broken LF module.
Sorry for the trouble, problem seems resolved now


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