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.
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.
Continue reading “Parts: 1-Wire Temperature Sensor (DS1822)”
The DS1077 is a 5volt, 133MHz to 16kHz programmable clock source. The internal frequency divider is configured over a simple I2C interface, and the chip requires no external parts. Not bad for under $2. We used the Bus Pirate to test this chip before using it in a project. Grab the datasheet (PDF) and follow along. Continue reading “Parts: 133MHz-16.2kHz Programmable Oscillator (DS1077)”