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#1 2019-12-04 00:28:28

jramb0
Contributor
Registered: 2016-11-07
Posts: 23

unable to write b & d on t55xx

Hi guys,

I am trying to write the block and data on a t55xx card.

My previous attempt was working like a charm on the same fob type as what I am currently using.

When I type the command to write the data ( lf t55xx write b 0 d ABCDEF 1 )... it does not throw any error.

Somehow, if I run a lf t55xx dump it gives me the following:

proxmark3> lf t55xx dump
Reading Page 0:
blk | hex data | binary
----+----------+---------------------------------
Reading Page 1:
blk | hex data | binary
----+----------+---------------------------------

I am missing anything?

I also noticed that when I launch the latest official build I get the following:

#db# Performing i2c bus recovery
#db# I2C bus recovery  error: SDA still LOW
#db# Performing i2c bus recovery
#db# I2C bus recovery  error: SDA still LOW
Prox/RFID mark3 RFID instrument
bootrom: master/v3.1.0-163-g00848e0-suspect 2019-11-25 13:35:11
os: master/v3.1.0-163-g00848e0-suspect 2019-11-25 13:35:14
fpga_lf.bit built for 2s30vq100 on 2019/11/21 at 09:02:37
fpga_hf.bit built for 2s30vq100 on 2019/11/13 at 14:52:19
SmartCard Slot: available

Should I be worried about the "I2C bus recovery  error: SDA still LOW"

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#2 2019-12-04 12:11:02

mwalker
Contributor
Registered: 2019-05-11
Posts: 210

Re: unable to write b & d on t55xx

Not sure about the I2C #db#

On the T55xx
lf t55xx write b 0 d ABCDEF 1
This seems like a weird command ?  i.e. you cant write to block 0 page 1.  If writing to block 0 page 0 i.e. (lf t55xx write b 0 d ABCDEF) then the data ABCDEF would seem to be an invalid card config block.

Also prior to a dump, did you run the lf t55 detect, if so what was the result ?

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#3 2019-12-05 02:10:46

jramb0
Contributor
Registered: 2016-11-07
Posts: 23

Re: unable to write b & d on t55xx

lf t55xx write b 0 d ABCDEF 1 is an example as I didn't want to but the real hex data on here.

Trying to write block 0 to 3 on page 1 and block 0 to 7 on page 0.

As I said, the first attempt to write the data using the exact same command to the exact same blank fob model worked... now it doesn't seem to work now. not sure if i am crazy!

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#4 2019-12-05 06:37:32

mwalker
Contributor
Registered: 2019-05-11
Posts: 210

Re: unable to write b & d on t55xx

A few things to think about.
Block 0 Page 1 is a read only block that is linked to (the same as) Block 0 Page 0
Block 3 Page 1 is the Front End config, so may affect a few things.
Block 0 Page 0 is the config.
It would help to see what is currently in the config blocks.
Block 0 Page 0 and Block 3 Page 1

Can you read the current data ?  Was there a password set ?

You could try to wipe the card/reset the config blocks (if not locked)

Note, I would start by makeing sure you can read the "new blank fob"
eg.
lf t55 detect
(show result)
lf t55 dump
(Would be good to see block 0 page 0 and block 3 page 1)
If you cant read a new blank fob, then that should be resolved first.

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#5 2019-12-10 11:46:35

jramb0
Contributor
Registered: 2016-11-07
Posts: 23

Re: unable to write b & d on t55xx

I think that was me confusing myself... thanks for your help mwalker!

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