Some of these chips, though, don’t have native SPI or I2C interfaces; instead, everything is done through a USI, or Universal Serial Interface module. [Jan] found the stock I2C USI module was a ...

The circuit shown can be used to interface multiple serial devices to the I 2 C bus, even if they lack the extended-addressing capability required.. Information transfer be-tween I 2 C devices ...

A recent newsletter mentioned a testing and debugging module called the “Bus Pirate” that helps people overcome problems with serial buses. People can simulate bus operations for 1-Wire, I2C, SPI, ...