Now that we’ve become used to USB you really appreciate the facility to connect or disconnect devices without having to turn the power off first. This was also true for RS232 (but not with LPT), but you never felt at ease with it. I2C or SMBus devices are unfortunately not hot swappable. A component that solves half of the problem (the switching part) has been introduced recently by Linear Technology.
The LTC4300 is a 2-wire interface buffer that can isolate the signals between peripherals and the bus, making it possible to add another device to the bus at any time, without causing any interference. The next step is more difficult and you will have to find the solution for this yourself: you have to find a way to detect when there is no activity on the bus. At that time the interface chip can be enabled, causing the peripheral to be connected to the bus. The buffer contains active pull-ups, permitting the use of high-value (10 kΩ) pull up resistors. More information about the LTC4300 can be found at www.linear. com.