drivers/periph_timer: add timer_get_closest_freq()
#20581
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maribu
added
Type: new feature
maribu
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leandrolanzieri,
aabadie,
MichelRottleuthner and
MrKevinWeiss
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Area: tests
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crasbe
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drivers/include/periph/timer.h
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| * @brief Search the frequency supported by the timer that is closest to | ||
| * a given target frequency, efficiently | ||
| * | ||
| * @param dev Timer to get the closest supported frequency for |
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Doxygen will create a reference to the Timer struct of Paho MQTT, but that's not really your fault. A workaround would be to write timer in lowercase.
If you decide to change it: The same is true for the description in timer_query_freqs 😅
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If you decide to change it: The same is true for the description in
timer_query_freqs😅
Can you address this as well?
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You can squash that change directly.
mguetschow
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Apr 2, 2025
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Successfully tested on a BOARD=z1 with MSP430 (will do the same for #20582)
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You can squash the fixups. |
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Add an API to search for the frequency supported by a timer that is closest to the given target frequency. This is in fact non-trivial to get right, as pre-scaler registers can be 16 bit or even 32 bit in size, making a naive loop over all possible pre-scalers too expensive (computationally). Co-authored-by: mguetschow <mikolai.guetschow@tu-dresden.de>
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crasbe
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Thx a lot! |
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Contribution description
This provides a helper function that builds upon the
periph_timer_query_freqsfeature to find the frequency supported by a given timer that is closest to a given target frequency.This functionality isn't as straight forward to implement, as a naive implementation iterating over all supported pre-scalers will be prohibitively expensive when the pre-scaler register is 16 bit or even 32 bit wide.
Instead, a binary search is performed plus some corner case handling in case the target frequency cannot exactly be met, in which it is checked if the highest frequency below the target or the smallest above the target is closer.
Testing procedure
The test app was extended:
Issues/PRs references
None