ERIKA Enterprise is an innovative RTOS for small microcontrollers based on an API similar to those proposed by the OSEK/VDX Consortium.The ERIKA Enterprise kernel implements innovative scheduling algorithms such as Fixed Priority with preemption thresholds, Stack Resource Policy (SRP), and Earliest Deadline First (EDF), which can be used to schedule tasks with real-time requirements.
ERIKA Enterprise is available in double licensing, both GPL and commercial, and has a very small footprint: typically, a minimal installation of ERIKA Enterprise consumes from 800 to 2000 bytes of code, for the implementation of a fixed priority scheduling kernel with stack sharing and binary mutexes.
Evidence presents the Erika Enterprise RTOS, a multi-processor real-time operating system kernel, which is available for several platforms from Altera’s NIOS II Softcores to the dsPIC (R) DSC micro-controllers family.
The Erika Enterprise kernel introduces innovative concepts, mechanisms and programming features to support the future generation of micro-controllers and multicore systems on-a-chip.
Erika Enterprise offers the availability of a real-time scheduler and resource managers allowing the full exploitation of the power of new generation micro-controllers and multicore platforms while guaranteeing predictable real-time performance and retaining the
programming model of conventional single processor architectures.
The advanced features provided by Erika Enterprise are:
• Support for four conformance classes to match different application requirements;
• Support for preemptive and non-preemptive multitasking;
• Support for fixed priority scheduling;
• Support for stack sharing techniques, and one-shot task model to reduce the overall stack usage;
• Support for shared resources;
• Support for periodic activations using Alarms;
• Support for centralized Error Handling;
• Support for hook functions before and after each context switch;
The Erika Enterprise kernel has been developed with the idea of providing the minimal set of primitives which can beq used to implement a multithreading environment. The Erika Enterprise API as a reduced OSEK/VDX API, providing support for thread
activation, mutual exclusion, alarms, and counting semaphores.

Erika Data Book

Erika Official site