System Clock source in project using 'target' option

[the-risk-taker]

Hi,

I have project with following configuration (I'am targeting the same MCU as on NUCLEO-F103RB board):

<library>
   <options>
      <option name=":target">stm32f103rbt6</option>
      <option name="modm:build:openocd.cfg">openocd.cfg</option>
      <option name="modm:build:cmake:include_cmakelists">False</option>
      <option name="modm:build:scons:include_sconstruct">False</option>
   </options>
   <modules>
      <module>modm:build:scons</module>
      <module>modm:build:cmake</module>
      <module>modm:platform:core</module>
      <module>modm:platform:gpio</module>
      <module>modm:platform:timer:2</module>
   </modules>
   <repositories>
      <repository><path>../submodules/modm/repo.lb</path></repository>
   </repositories>
</library>

I want to play around with timers and interrupts - exactly to use the setPeriod() method:

Timer2::setPeriod(uint32_t microseconds, bool autoApply = true)

But setPeriod() method expects the SystemClock template parameter - from where or how can I provide the system clock value?

[Updated]
I just figured it out that if I provide a struct like one from modm/src/modm/board/nucleo_f103rb/board.hpp for NUCELO board in my main.cpp:

struct SystemClock
{
    static constexpr uint32_t Frequency = 72'000'000;
    static constexpr uint32_t Ahb = Frequency;
    static constexpr uint32_t Apb1 = Frequency / 2;
    static constexpr uint32_t Apb2 = Frequency;
// ...

    static bool inline enable()
    {
        // ...
    }
}

Then I can use setPeriod() method as follows:

Timer2::setPeriod<SystemClock>(period);

(1) Is this the correct approach? Or is there a better way?

(2) Maybe I don't know how to use the documentation, but the documentation didn't help me at all. Can anyone tell me where I can find this topic in the documentation?

[salkinium]

(1) Is this the correct approach? Or is there a better way?

That's how it is intended to be used, you can also define multiple SystemClock structs to switch them at runtime (at the cost of calling Peripheral::initialize<SystemClock123>() for everything you use anytime you switch).

Can anyone tell me where I can find this topic in the documentation?

The Timer API is simply lacking documentation, sorry about that!

[salkinium]

I intended for the SystemClock to be autogenerated using the machine-readable clock tree data also found in CubeMX, but it was more complicated than I thought and there were just easier and more important things to do in the meantime…

[rleh]

As an intermediate step we could seperate the hand-coded SystemClock structs from the :board:* modules and put them in there own lbuild modules so that the code can be reused in Custom board support packages (instead of being copy-pasted).
Later these lbuild modules can be extended with autogenerated clocks, multiple options, ...