Disclosure: I work at Amazon, but nowhere near Lab126 where these bad boys get engineered. I’m acting on my own accord using technology that anyone can have themselves. I have no internal information about these and am doing it out of my own curiosity. (Yes, that’s a leadership principal, so there!)

Photo May 01, 3 47 37 PM

A few bits of 28 AWG wire, some tape, and I made a very crude breakout system for the Kindle. I had read elsewhere that the general pinout is like this:

  1. Ground
  2. I2C
  3. I2C
  4. Battery
  5. Ground

The grounds are isolated. I’m guessing that pin 1 is the reference for the I2C bus and pin 5 is the battery ground.

This led to me hooking up the system to the scope:

Photo May 01, 3 42 31 PM

So, to note here I’m probing yellow as pin 2, blue as pin 3, and battery as pink (though I turned it off on the display since it was just noisy). All of these are referenced to pin 1.

Photo May 01, 3 43 01 PM

Sure enough! Pin 3 is clock while 2 is data!


There’s a crap-ton of pickup on the signal. With the lights turned on it was even worse. It was good enough to get a decode though.


I’ve not had a chance to dive into this, but here’s a raw dump of the data stream:

Bus Definition: I2C
 Time  Repeat Start  Direction  Address  Data  Missing Ack
1.26E-03  Read 55  D1 10
3.12E-03  Write  1B  4F
4.25E-03  X  Read  1B  25 55 04  X
6.64E-03  X  Read 55  D1 10
8.47E-03  Write 55 14
9.91E-03  X  Read 55  00 00
1.18E-02  Write 55 6
1.30E-02  X  Read 55  6C 0B
1.48E-02  Write 55  0C
1.60E-02  X  Read 55  D3 04
1.79E-02  Write 55 12
1.91E-02  X  Read 55  B8 04
2.09E-02  Write 55  2C
2.21E-02  X  Read 55  63 00
2.40E-02  Write 55  2A
2.52E-02  X  Read 55  00 00

Lots of chatter on address 0x55. I’ve not had a chance to guess what might be there. But there’s certainly a lot of activity going on there.

When I get back from my vacation I’ll set up a trace to see if anything other than 0x55 gets any action.