[Q] SMBUS

SMBUS is an extension of I2C (or TWI, as it is also called, to avoid patent disputes with Philips). It has some special limitations and special reserved addresses.

If the addresses of the devices do not conflict and the special properties of SMBUS are not needed, yes.

I'm using SMBUS, I2C and TWI devices together on a common bus bit-banged by the master processor.

HTH

Tauno Voipio tauno voipio (at) iki fi

SMBus added special broadcast messages within the I2C protocol. But everything is still addressed the same way, so unless a device is actually listening for the broadcast messages, they are benign. Like Tauno, I implemented a system with a mix of SMBus and I2C devices without issue.

That said, one of the items SMBus allows is for the pullup voltage to extend up to 12V, whereas every I2C-specific device I've encountered tops out at

5V. If you are designing the whole system, there's no issues; if you are interfacing with a black-box that has a 2-wire SMBus interface, I'd be sure of a) whether that system expects your system to provide the pull-up or b) that its' pullup is at a voltage that is not-harmful to yours.

Finally, Philips has the full I2C spec on their site, and you can find the SMBus spec on

and more info on the SBS (which spawned SMBus) at

Cheers SM