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#1 2017-09-06 07:38:08

Registered: 2017-09-05
Posts: 2

Proxmark3 rdv3 easy HF bad?

I picked up a proxmark rdv3 easy. After getting the bootrom.elf and fullimage.elf flashed I noticed trouble with the integrated HF antenna

Running the latest master branch.

Prox/RFID mark3 RFID instrument
bootrom: master/v3.0.1-75-g1dae981-suspect 2017-09-05 04:40:59
os: master/v3.0.1-75-g1dae981-suspect 2017-09-05 04:41:00
LF FPGA image built for 2s30vq100 on 2015/03/06 at 07:38:04
HF FPGA image built for 2s30vq100 on 2017/07/13 at 08:44:13

uC: AT91SAM7S256 Rev D
Embedded Processor: ARM7TDMI
Nonvolatile Program Memory Size: 256K bytes. Used: 194722 bytes (74%). Free: 67422 bytes (26%).
Second Nonvolatile Program Memory Size: None
Internal SRAM Size: 64K bytes
Architecture Identifier: AT91SAM7Sxx Series
Nonvolatile Program Memory Type: Embedded Flash Memory

Attempting to tune the antennas

proxmark3> hw tune

Measuring antenna characteristics, please wait.........
# LF antenna: 37.40 V @   125.00 kHz
# LF antenna: 36.02 V @   134.00 kHz
# LF optimal: 39.88 V @   127.66 kHz
# HF antenna:  0.00 V @    13.56 MHz
# Your HF antenna is unusable.
Displaying LF tuning graph. Divisor 89 is 134khz, 95 is 125khz.

No GUI in this build!

I disabled the stacked board and took a look at the embedded HF antenna. I didn't see any damage or anything remarkable. No obvious soldering mistakes. What are the debugging steps for the HF antenna? Is there anyway to determine if this is bad hardware or a software issue ? The LF seems to work well. I was able to read, clone and read again some hid cards.


#2 2017-09-11 09:14:57

From: Vic - Australia
Registered: 2017-05-01
Posts: 33

Re: Proxmark3 rdv3 easy HF bad?

First off all, make sure your firmware is matched to the client software you are using. Also make sure you are using a stable version of the software.

If you've done all the standard software troubleshooting then it definitely looks like it's defective in some way - the HF antenna cannot be disconnected on this design without physically cutting PCB traces. The problem may not be anything major but unless you want to sink time into repairing the board yourself, the best option would be to return it and get a new one.

If replacing it isn't an option and you've got a multimeter it might be worth trying to trace continuity from the antenna back through to pin 4 on the microcontroller (AD5) - this is the AMPL_HI signal that hw tune is trying to measure. There could just be a bad resistor along that path. I investigated the board layout of my PM3 easy clone and the connections seem to pretty closely follow the original schematic, so the schematic may be helpful to you too: … schema.pdf There are a couple of non-essential chips that haven't been included on the board though (AD8052 and TLV3052)


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