what is "hot-swap" in I2C?

[akshada]

hello,
I know the basic that with hot swap the device connected to the master via I2C bus can be replaced with new one.
I would like to know the consequences of it.
for example i swap an eeprom with a new one.how the new eeprom will react.
why it is done?
can anybody give some brief on hot swap in I2C.

Thanks in advance?

 

[permute]

a practical example is HDMI, which has some high speed IO for the video/sound, and then has I2C for control. If you were designing a monitor, or a video out device, you would need to support the plugging in of one or more monitors.

Hot swap can have issues with master reads in that the master will be ack-ing the read data bytes. If a slave is disconnected during a read, the master will see all 1's for the data bits. Some devices will include a checksum (ideally one where all 1's is not a valid choice) which helps to solve that corner-case.

I2C devices are addressed. If a device is hot swapped with one having the same address, there could be issues. If the master polls devices regularly, then it would be able to detect normal unplug/pluge events. Likewise, some circuits might provide an interupt to the uC for the connect plugged/unplugged.