[rtl872x] Fix millis() rollover

[scott-brust]

Problem

HAL_Timer_Get_Milli_Seconds() / HAL_Timer_Get_Micro_Seconds() Eventually reset after ~1 hour of execution. This results in millis() rolling over to zero.

Solution

It appears that the problem is due to integer promotion (in this case, demotion?) when calculating elapsed micro seconds:

constexpr int US_PER_OVERFLOW = 65536;                 // 65536us
...
return usSystemTimeMicrosBase_ + state.overflowCounter * US_PER_OVERFLOW + ticksToTime(state.curTimerTicks);

Making US_PER_OVERFLOW a uint64_t seems to solve the problem.

Steps to Test

Modify timer_hal.cpp init() and start() functions to start the overflowCounter_ at a value close to 65536

        overflowCounter_ = 65000;

Run the app and observe the uptime millis incrementing beyond 0004294659

Example App

tinker or any app with timestamp logging

References

Links to the Community, Docs, Other Issues, etc..

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[avtolstoy]

🎉