1-Wire device introduction

     1-wire or One Wire is a device communications bus system using a single wire for data and second for earth/ground/return for a total of 2 wires in reality. The technology was developed by Dallas Semiconductor (now Maxim) and all sorts of devices are available from temperature reading devices to eeprom's. Each device is created with a unique serial number or device ID in addition to its other capabilities. For this reason they are showing up as device security devices with this unique ID being an encryption key or hashed with data to provide security.

     There are many different packages that 1-wire devices are available in, from standard TO-92 and SOIC packages to i-button devices. No matter the package they come in they can all be accessed through the same 1-wire adapters (some hardware hacking required) because they all use the same 1-wire protocol. Here are some examples of the devices I have encountered.

DS2433 4kb EEPROM in a TO-92 package

DS1904 iButton

DS2433 4kb EEPROM in a SOIC package

 

      I happened to have a few extra DS9490B USB to 1-wire readers handy but I didn't have anything to read the SOIC or TO-92 package chips so time to improvise.

I started with a standard off the shelf DS9490B USB adapter

Removed the cap and iButton and soldered two wires to the internal contacts of the iButton reader, one to the large copper contact on the board for the data line and one to the large ground shield that holds the button in place.

I then added some alligator clips to the wires. In the future I think some smaller ones would be easier to use, but I had these lying around so they will do for now.






Next post we will put our newly hacked device to use...