Some details on "The Other Half" http://talk.maemo.org/showpost.php?p=1380982&postcount=117

• 3,3V VDD (max 300mA, preferrably < 150mA to avoid thermal issues)
• 1,8V I2C (400kHz default setting in kernel)
• Other half expected to work in slave mode, phone is master
• Dedicated INT GPIO (1,8V) for interrupts
• Further details and API examples will be published at later phase on coming SDK releases.

plus a collection of interesting #TheOtherHalf ideas by @YvesPE on twitter https://twitter.com/YvesPE/media