Skip to main content

Wiring little wires to stuff or “How did I get fingerprint scanner”

So I had/have a semi-old dead laptop. The motherboard is dead, everything else works. It’s a Dell XPS M1330. It has a fingerprint scanner that made my curious. How does it work? How is it connected and can I use it?

I ripped the laptop open and extracted all kinds of fun stuff including the fingerprint sensor.

It has a little chip with a writing  / / TCD42A1DN0 / /

So I started investigating.

First thing that threw me off was the 6 pin ribbon cable (USB typically uses 4).

  • Finding ground pin is the easiest – Found that.

  • Found the power pin- It was a line that had a capacitor connected with the ground. So I assumed this was the power pin.

  • Two pins are unpopulated.

  • Two pins are connected to resistors – starts to seem like USB data lines~.





Interfacing it.

Typically all internal laptop stuff uses 3.3V. So that seemed a safe way to go. I need to use a voltage converter to step down from 5V.

It has a ribbon cable, so that’s a no go. Removed that and the plug and decided to connect wires directly to it.

This needs some soldering under a microscope because this stuff is tiny.

Soldered everything up and time to test.

USB data + and –  //connected it randomly, 50/50 chance that it goes correctly the first time. (But in real life I connect it always backwards the first time.)



Connected it a perforated board and hooked up the USB cable.



Time to roll

Connected to a computer. Windows detected it (Data+ and Data- went right ways the first time). Windows installed drivers automatically and restarted the computer.


Voila, it is working!



  1. hi i need a help here i don't know how to pinout my finger print reader ... can you help me

  2. Aluminum wire was used from the mid 1960's to the late 1970's. It is rare to find aluminum wire in homes constructed after 1980.Jim Rohal

  3. This comment has been removed by a blog administrator.


Post a Comment

Popular posts from this blog

My take on a nixie clock

As a present I decided to build a nixie tube clock. It was essential to ditch my close-enough attitude and make it look as good as possible. For me the simplest way to complete this idea was to use a microcontroller. I am not cool enough to build a clock out of discrete logic, maybe in the future.

I had couple of nixie tubes lying around, I ordered some more to have a total of six. So the clock consist of an Arduino Nano, RTC DS3231, nixie tubes - IN-14 and a power supply. From the start I knew the biggest challenge is building the enclosure. I learned that the easiest way to drive these nixie tubes is with a driver called - К155ИД1.

It’s a binary to decimal decoder and it works quite elegantly. Depending on the binary input it enables the right output.

It does all the heavy lifting. And then I used three shift registers to drive all the drivers.

In addition I bought a nixie tube power supply that supplies the 170v I need. I could have used 220v wall power but I do not trust myself enou…

My take on the PA0RDT Mini Whip antenna.

I like shortwave radio because you can receive signals from all over the world, also there are all kinds of mysterious signals to explore.

In the grand scheme - the lower the frequency, the bigger antenna you would need. Well, there are all kinds of antenna designs but I like to think like that way. For example, I have a 27 MHz dipole on my roof that is around 5.3 meters long. If I wanted to listen to lower frequencies ~ around 3 MHz, for optimal performance I would need around 50 meter antenna, so using dipole for lower frequencies is not very space efficient, especially if you do not have any room.

So I decided to build the Mini Whip antenna. It is popular, simple to build and on paper receives frequencies from 10 kHz to 30 MHz, and also it is super tiny.

There are some variations between different designs, but the basic idea is the same.

The schematic I followed.

During my tests it performed well, I was able to receive DCF77 signal for the first time. All other bands seemed to work as w…

RFID experiments

Radio-frequency identification (RFID) is a way to use electromagnetic fields to send and receive data wirelessly. The system consists of two parts: reader and a tag.  Tags can be passive or active. I think the most popular are passive tags. Meaning, there are no batteries needed, the power comes from the reader. The reader constantly sends out an interrogation signal and when a tag absorbs the energy and powers up, it radiates back information from the embedded chip.

Then it divides further - different frequencies, generations, encryptions etc.

Also one popular part is NFC (Near Field Communication) which has better security and other improvements. Latest phones usually come with NFC read/write capabilities built in.  So you can pay with your phone or touch phones together to share information. A lot of possibilities.

RFID/NFC is quite popular in our commercial world.

Anti-theft – stores use it to stop people stealing stuff.
Tracking people - putting tags inside shoes to track people, some…