Software Timer

LibXR provides a lightweight software timer that can even be used in bare-metal environments.

With FreeRTOS and ThreadX, the software timer runs in a thread of its own, which needs a thread priority and a stack depth.

Example

For bare-metal systems, the following code will be generated without any parameters:

PlatformInit();

In FreeRTOS and ThreadX projects, the thread priority and stack depth are passed:

PlatformInit(static_cast<uint32_t>(Thread::Priority::MEDIUM), 1024);

Thread Priority

The generated code expresses thread priorities as levels of LibXR::Thread::Priority, from low to high IDLE, LOW, MEDIUM, HIGH and REALTIME. The software timer, the terminal thread and the watchdog thread all use this form.

LibXR converts the levels to RTOS priorities by the RTOS priority count. On FreeRTOS the step is (configMAX_PRIORITIES - 1) / 5; IDLE is 0 and LOW to REALTIME are 1 to 4 steps. With a configMAX_PRIORITIES of 7, for example, MEDIUM is 2, and with 56 (the CubeMX default for CMSIS_V2) it is 22. On ThreadX lower numbers are higher priorities: REALTIME is 1 and HIGH to IDLE are 1 to 4 steps, the step being (TX_MAX_PRIORITIES - 1) / 5.

Configuration File

software_timer in User/libxr_config.yaml sets these two arguments; bare-metal projects do not use it:

software_timer:
  priority: 2
  stack_depth: 1024

priority takes 0 to 4 or a level name in any case; 0 to 4 stand for IDLE, LOW, MEDIUM, HIGH and REALTIME, and the default is 2 (MEDIUM). Any other value stops generation. The thread_priority of the terminal and the watchdog takes the same values.

After editing the file, regenerate the code with the commands in Regenerating the Code.