Hi,

My question is i2c is hot plug-gable or not ?
Please justify also.

As I know I2C is not but PMBus is hot plug-gable .Why the difference between two?
PMBus is subset of I2C only.

Thanks

 

I2C is not hot-pluggable by itself. That is because it is a simple low-level link between devices. To make a hot-pluggable system using I2C as the basic communication link, you add a higher level protocol that has additional functionality.

SMSbus is an example. It uses the messaging capability of I2C to send messages to the devices on the bus to detect when a device has been added or removed and act accordingly. Adding a device requires that it be detected, identified, and assigned an address at the minimum. Devices that are removed are noted so that the system knows that that functionality is no longer present. All of that is done by the higher level protocol using I2C to do the messaging. PMbus is a similar arrangement.

Besides software protocols, hot-plugging requires that adding or removing a module does not cause electrical problems that would affect bus communications. If adding a device caused noise on SDA or SCL, that could cause problems. Hot-pluggable hardware designs take that problem and more into account. The higher level protocols will usually include methods to detect when messages get clobbered from any cause, including hot-plugging, and incorporate ways to fix that - retry bad messages, etc. As always, the formal bus and protocol specifications will spell out how this is all managed.

It's a big subject but I hope that gets you started.