96boards Sensor board: comm protocol with ATMEGA?

Part of the merit of the Sensor board is that the ATMEGA on the board can provide a variety of I/Os that the 96Board itself typically lacks, such as ADC and PWM, not to mention just additional quantity of I2C, SPI, GPIO and so on.

Has a protocol been established (and corresponding ATMEGA and ARM libraries) such that the host application software on the 96Board can just treat the ATMEGA’s I/Os the same way as the I/Os on the 96Board itself?

Thanks.

… in the manner of the IOIO-OTG board (albeit IOIO is connected to a host via USB).