Bus Pirate

Description

I'm talking about this beast

Installation

My udev rules

I added a /dev/bus_pirate symlink by following this post:

$ ATTRS=$(sudo udevadm info -a -p \
          $(sudo udevadm info -q path -n /dev/$(dmesg|\
              grep "FTDI.*attached"|\
              tail -n 1|\
              grep -o "ttyUSB[0-9]\+"))|\
          egrep "ATTRS{(serial|idVendor|idProduct)}"|\
          head -n 3)
$ echo "SUBSYSTEM==\"tty\"" $ATTRS "SYMLINK+=\"bus_pirate\""|\
  sudo tee /etc/udev/rules.d/91-usb-buspirate.rules

If you've problems with modem-manager trying to access the device (as seen in /var/log/syslog), you can add the following rule:

ATTRS{idVendor}=="0403" ATTRS{idProduct}=="6001" ENV{ID_MM_DEVICE_IGNORE}="1"

Firmware upgrade

My bus pirate is a hardware v3b, firmware v4.1 and boodloader v4.1
To upgrade those two last ones:
Latest stable firmwares are available here
Let's take Bus.Pirate.firmware.v5.9.zip
And for the bootloader we'll follow this procedure, using this zip
To use the uploader, see here

$ screen /dev/bus_pirate 115200
Type "$" to enter bootloader mode
Press ctrl-a \ y to quit screen
$ ./pirate-loader_lnx --dev=/dev/bus_pirate --hex=BPv3-bootloader-upgrade-v4xtov4.3.hex
$ screen /dev/bus_pirate 115200
Type "yes" to upgrade bootloader
Press ctrl-a \ y to quit screen
$ ./pirate-loader_lnx --dev=/dev/bus_pirate --hex=BPv3-Firmware-v5.9.hex
Unplug/replug

Firmware v5.9 extra contains a few more things but only those modes:

Firmware v5.9 (r529) [HiZ 2WIRE 3WIRE KEYB LCD DIO]

While for normal firmware:

Firmware v5.9 (r539)

Hardware mod

I found the 2 greed LEDs of bus pirate v3b a bit weak especially through the plastic box so I replaced their resistors (1.1k) by resistors of 100 ohms.
It may vary with the exact LEDs in use with your board so don't assume 100 ohms will work on your own board!

Usage

CLI

screen /dev/bus_pirate 115200
i
Bus Pirate v3
Firmware v4.2 Bootloader v4.2
DEVID:0x0447 REVID:0x3043 (B5)
http://dangerousprototypes.com
HiZ>
ctrl-A \ (y) to quit

Pinouts

See also http://dangerousprototypes.com/category/pin-reference/
WARNING in the nice sticker colorscheme, the cable is put upside-down (it's said in the comment but I missed it completely the first time)
So if you put your cable going "outwards of the PCB", as seen in the introduction picture, pinout is the following:

GDN      - brown, black EZhook
    +3.3 - red
+5       - pink,  red EZhook
    ADC  - yellow
Vpu      - green
    AUX  - blue
CLK      - violet
    MOSI - grey
CS       - white
    MISO - black

We can perform a self-test with the cable by connecting together red+yellow and pink+green, then simply run "~" on the CLI.

Logic analyzer

See http://dangerousprototypes.com/docs/Logic_analyzer_mode

Installing SUMP is not that easy...
I chose to try a fork of it mentioned in the comments of Sump PC client page

wget http://dl.dropbox.com/u/1026013/Java/Logic%20Analyzer/Logic%20Analyzer.zip
unzip Logic%20Analyzer.zip
sudo aptitude install libftdi-dev librxtx-java

I modified the runme as following for my Debian, and to be able to use a symlink to the runme:

#!/bin/bash
if [ -h $0 ]; then
    DIR=$(dirname "$(readlink $0)")
    cd "$DIR"
fi
java -Xmx256m -cp /usr/share/java/RXTXcomm.jar:analyzer.jar \
     -Dgnu.io.rxtx.SerialPorts="/dev/bus_pirate" \
     -Djava.library.path="/usr/lib/jni" \
     org.sump.analyzer.Loader

Now trying it:
We've only to change the recording size to 4k or lower, other params should be ok
Pins & channels:

chan0 - CS   - white
chan1 - MISO - black
chan2 - CLK  - violet
chan3 - MOSI - grey
chan4 - AUX  - blue
        GND  - brown

See also other analyzers:

• http://dangerousprototypes.com/2010/07/23/logic-analyzer-client-roundup/

I also tried this fork: http://www.lxtreme.nl/ols/
and changed a bit the run.sh script to handle it through symlink :

if [ -h $0 ]; then
    DIR=$(dirname "$(readlink $0)")
    cd "$DIR"
    BASEDIR=.
else
    BASEDIR=$(dirname -- "${0}")
fi

Practice

7816-3 T=0 at arbitrary baudrate

I wanted to sniff an ATR from an autonomous reader
ATR was 3B 67 00 00 00 00 00 00 00 90 00
But when trying with the UART mode, I couldn't get the proper bytes being decoded
Let's first have a raw trace to have a rough idea of the signal:
Using the logical analyzer on I/O, sampling 10kHz + a trigger on RST

ATR in bin  I/O signal            UART 2400
3B 00111011 0.11011100.1111... <> 9D 10011101
67 01100111 0.11100110.1111... <> B3 10110011
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
00 00000000 0.00000000.1111... <> 80 10000000
90 10010000 0.00001001.1111... <> C8 11001000
00 00000000 0.00000000.1111... <> 80 10000000

=> none of the baudrates was correct enough
Clock of the autonomous reader was 1.05MHz (measured with an oscillo, bus pirate needs a CLK for one whole second to be able to measure the frequency)
smartcard baudrate = CLK / 384
So in our case => ~2734 baud
While usually T=0: 9600 bit/s, 8 data bits, 1 parity bit, 2 stop bits, no handshake and even parity, + inversion compared to RS232 signals

See UART doc: we need firmware >= 5.1 to have full BRG control

BRG calculations:

• baudrate=4000000/(BRG+1)
• BRG=(4000000/baudrate)-1

So in our case => BRG=~1462

Let's try:
Case 1:

m3 10 1400 2 1 1 1 [

1461 produced some errors occasionally and I had better results with a slightly higher baudrate (2855 baud)

So choosing the proper baudrate is extremely important when sniffing busses not using a standard baudrate!
We couldn't measure the CLK frequency very well so we had to do trial & error to find a suitable baudrate.

On some readers, CLK signal is kept running all the time, from insertion or during operation.
In that case, we can measure very precisely the frequency with the bus pirate: link CLK to AUX probe and press "f" (works both in HiZ or UART)
Here are some measures on various readers:

Reader	CLK	baudrate	BRG	Remarks
Dell RT7D60	4009216 Hz	10441	382
ACR38U	4009216 Hz	10441	382
Vasco DP905	3700736 Hz	9637	414	mode 9600 works too (416)
Vasco DP810	~1.05MHz	~2734	1400	better than BRG=1462
Vasco DP840	~1.05MHz	~2734	1400	better than BRG=1462
Gemalto PC USB-SL	4000768Hz	10419	383
Gemalto "digipass"	1501696	3911	1022