Overview

MicroEJ Core Engine Abstraction Layer implementation for FreeRTOS.

This module implements the LLMJVM Low Level API for MicroEJ Platforms connected to a Board Support Package based on FreeRTOS.

See the MicroEJ documentation for a description of the LLMJVM functions:

• LLMJVM: MicroEJ Core Engine
• MicroEJ Core Engine: Implementation

Usage

1. Install src and inc directories in your Board Support Package. They can be automatically downloaded using the following command lines:

    svn export --force https://github.com/MicroEJ/AbstractionLayer-Core-FreeRTOS/trunk/inc [path_to_bsp_directory]    
    svn export --force https://github.com/MicroEJ/AbstractionLayer-Core-FreeRTOS/trunk/src [path_to_bsp_directory]

2. Implement the MicroEJ time functions, as described in microej_time.h.

3. The LLMJVM_IMPL_scheduleRequest schedule request function in LLMJVM_FreeRTOS.c uses a software timer. In order to correctly schedule MicroEJ threads, check the following elements in the FreeRTOS configuration file:

   • Timers are enabled with #define configUSE_TIMERS 1
   • configTIMER_TASK_PRIORITY is higher than MicroEJ task priority
   • configTICK_RATE_HZ: can depend on the application, if it needs a 1 ms precision then the tick rate would be 1000 Hz, the recommended value is between 100 Hz and 1000 Hz

Requirements

None.

Validation

This Abstraction Layer implementation can be validated in the target Board Support Package using the MicroEJ Core Validation Platform Qualification Tools project.

Here is a non exhaustive list of tested environments:

• Hardware
  • STMicroelectronics STM32F7508-DK
  • Espressif ESP-WROVER-KIT V4.1
• Compilers / Integrated Development Environments:
  • IAR Embedded Workbench 8.50.6
  • STM32CubeIDE version 1.3.0 (using GNU GCC toolchain)
  • Espressif IoT Development Framework (esp-idf) v4.4.4 (using GNU GCC toolchain)
• FreeRTOS versions:
  • FreeRTOS V10.4.3
  • FreeRTOS V10.2.0
  • FreeRTOS V8.2.0

MISRA Compliance

This Abstraction Layer implementation is MISRA-compliant (MISRA C:2012) with some noted exception. It has been verified with Cppcheck v2.10. Here is the list of deviations from MISRA standard:

Deviation	Category	Justification
Rule 8.4	Required	The Cppcheck analysis is made only on this LL code
Rule 5.5	Required	Intentional usage of macros to define native functions.
Rule 7.2	Required	Error detected in FreeRTOS third library.

Dependencies

• MicroEJ Architecture 7.x or higher.
• FreeRTOS 8.2.0 or higher.

Source

N/A.

Restrictions

None.

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Copyright 2020-2023 MicroEJ Corp. All rights reserved. Use of this source code is governed by a BSD-style license that can be found with this software.