[avr-chat] USI

[Keith Gudger]

I'm trying to figure out how to use the "USI" module in the AVR.
According to app note AVR307:

"The Universal Serial Interface (USI) present in AVR devices like the
ATmega169, is a communication module designed for TWI and SPI
communication.  The USI is not restricted to these standards.  It can be
used for UART communication as well."

1)  Has anyone used the USI to implement I2C or SPI?  Does it work
as well as the dedicated hardware?  Any known problems?

2)  Has anyone used the USI to make a UART?  According to the app note,
noise can be a problem.  It also looks like servicing the USI could be
complicated, too.

Any feedback is appreciated.  Thanks.

Keith