I2C in LPC11Uxx


Our microcontroller includes an I2C controller
It is on pins 15 and 16
The pins are open-drain (no output-1 capability)
The only pins without an internal pull-up

You can run as many I2C buses as you want, one GPIO pins
Just set the GPIO data register to 0
Then toggle between input and output mode

Other (older) LPC11 devices are much more braindead
When you turn from input to output, the pin value is preserved
They help you to prevent glitches
They prevent you from doing anything useful
So pins 15 and 16 are open-drain as a bug-fix for this
Two bugs sometimes cancel one another, but they remain bugs