Hacking an iButton

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Maxim’s iButtons, which are small ICs in button-sized disks, are starting to show up in more and more places. They have a range of uses, from temperature loggers to identification, and all use the 1-wire protocol to communicate. Over a furrtek, they hacked an iButton used for buying things from vending machines and created an infinite money cheat. They built a small rig based on the ATmega8 to read and write data to the chip. The data was encrypted, so it wasn’t feasible to put an arbitrary amount on the card. Instead, they used a similar technique to the Boston subway hack and restored a previous state to the iButton after something was bought. They also created a hand-held device to backup and restore the contents of a button for portable hacking.

[Thanks furrtek]

How-to: The Bus Pirate V2 with USB

buspiratev2goii450

Update, Saturday July 4th, 2009: All preorders are closed.

The Bus Pirate is a universal serial interface tool, we use it to test new chips without writing any code. It currently supports most serial protocols, including 1-Wire, I2C, SPI, JTAG, asynchronous serial, MIDI, and more. We added some other features we frequently need, like pulse-width modulation, frequency measurement, voltage measurement, bus sniffers, pull-up resistors, and switchable 3.3volt and 5volt power supplies.

The new v2 family adds USB power and connectivity to the best Bus Pirate design yet. We also reduced the part count and cost wherever possible. If you want to get your hands on some Bus Pirate USB goodness, Seeed Studio has assembled hardware for $30 (including worldwide shipping).

Read about the new design after the break.

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Parts: 1K 1-Wire EEPROM (DS2431)

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The Maxim DS2431 1K EEPROM is 1-Wire device that adds storage to a project using a single microcontroller pin. We previously interfaced a 1-wire thermometer, but this EEPROM is slightly different because it draws power directly from the 1-Wire bus. Grab the datasheet (PDF) and follow along while we read and write this simple 1-Wire memory.

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Parts: 1-Wire temperature sensor (DS1822)

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Download: buspirate.v0d.zip

Dallas/Maxim’s 1-Wire protocol is the most requested addition to the Bus Pirate.  We finally got some 1-Wire parts, and today we’ll demonstrate the DS1822 1-Wire digital thermometer. Grab the datasheet (PDF) and follow along.

This post is accompanied by release v.0d of the Bus Pirate firmware for hardware version 0. This includes the new 1-Wire protocol library, more configuration options, and other improvements.

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1-wire barometer


[David] put together this rather nice 1-wire barometer. An MPX4115 measures the pressure while an SMD DS2438 mounted to an 8 pin DIP socket provides the 1-wire interface. The writeup includes a nice description of the board layout and wiring, making this project accessible to just about anyone with a decent tip on their soldering iron.

1-wire thermostat control


For some reason, computer controllable thermostats are pretty freakin’ expensive. I found a reference to a 1-wire thermostat in this(mirror) sample senior project on home automation. It turns out that Dallas Semiconductor put one together a while back as an application for their TINI platform. (web-application server on a chip). The write-up has since vanished from their site, but I found it thatnks to archive.org. The thermostat used to run about $50, and a similar model still seems to be produced. The 1-wire interface is pretty simple – Maxim’s TINI board to control it: not so much. Just using the 1-wire interface with an inexpensive thermostat and controlling from a PC seems pretty viable to me. Just in case, I mirrored the 1-wire interface schematics here.