i2c: Set CCR
Fix I2C arbitration
io_expander: Add potentially useful i2c_transfer

This might be material for libopencm3
LEDs work!
schematic: Kill unused node
Clean up pinmuxing
Try getting ADC working
A few ADC clocking fixes
Fix default periods
ADCs work, working on timers
Various fixes
Fix up pinmuxing
PWM working