A host controller interface that speeds sensor integration

Smartphones and other devices have a rapidly increasing number of mechanical, motion, biometric and environmental sensors. This sensor proliferation creates significant design challenges, especially for software developers.

The MIPI I3C HCISM (Host Controller Interface) specification defines the building of a common software driver interface to support compliant MIPI I3C host controller (master device) hardware implementations from multiple vendors to more easily integrate value-added features for smartphones, wearables, Internet of Things (IoT), automotive and more.

MIPI I3CSM is a bus interface for connecting sensors to an application processor in a multi-vendor environment. It can combine multiple sensors in a device to streamline integration and improve cost efficiencies. The diagram below illustrates a high-level architecture of the two specifications.

I3C-HCI-diagram-700

Using MIPI I3C HCI

MIPI I3C HCI defines a common set of capabilities for the host controller and the software interface, allowing for the building of class definitions based on a common set of features. The definition allows for vendor-specific extensions and optimizations. The specification defines several optimizations based on typical usage. For example, the combo command feature allows for the efficient one-shot transfer of write and then read transfers on the bus.

Other key MIPI I3C HCI v1.0 features include:

  • Support for MIPI I3C main master device operation on the I3C bus
  • Two modes of operation: Direct data interface support (PIO mode), with programmable buffer depths for the transmit/response and data buffer, and DMA interface support (DMA mode) to support scatter gather transfers for data buffers
  • Power-efficient operation of the host controller, which helps maximize battery life in mobile devices
  • Support for I3C data rates, including I2C fast mode (up to 400Kbps), I2C fast mode+ (up to 1Mbps) and I3C SDR (up to 12.5Mbps)
  • Support for extended capabilities, including vendor-specific ones, to enable more sophisticated hardware or additional functionality

Visit the MIPI Alliance website to learn more about MIPI I3C HCI, as well as the entire portfolio of MIPI specifications.