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Create New RTX_Config.c

RL-ARM provides several versions of the RTX_Config.c file for ARM7™/ARM9™ RTX Kernel library. Each one configures the RTX kernel for a specific ARM device variant that RL-ARM supports. However the ARM family of devices is growing quickly, and it is possible that RL-ARM does not contain the configuration file for the device you use. In this case, you can take the RTX_Config.c file for the NXP device as a template and modify it for your particular ARM device.

RTX Kernel library for Cortex™-M has only one configuration file RTX_Conf_CM.c, which is common for all Cortex™-M device variants.

HW Resources Required

In order to run the RTX kernel, the following hardware resources are required from an ARM device:

  • Peripheral Timer for generating periodic ticks. It is better to use a peripheral timer with an auto-reload function. RTX also supports timers with manual timer (or counter) reload. However, this can generate jitter and inaccuracy in the long run. The RTX kernel needs a count-up timer. If the timer used is a count-down timer, you need to convert the timer value.
  • Timer Interrupts to interrupt the execution of a task and to start the system task scheduler.
  • Forced Interrupts to force a timer interrupt when isr_ functions are used. If an isr_ function is called, the kernel forces the timer interrupt immediately after the interrupt ends. The forced timer interrupt activates the task scheduler. It is possible that a task has become ready. If this task has a higher priority than the currently running task, a task switch must occur.

All hardware dependent definitions are extracted from the code and defined with configuration macros. This makes it possible to customize the configuration without modifying the code.


  • The RTX configuration files are located in the \Keil\ARM\RL\RTX\Config directory.
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