Add clock_configure_mhz function #2244
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As per new code in #2225 we should catch cases where the divider between 1 and 2. |
I guess that means you can't overclock the Pico to 66 GHz? 🤣 |
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See also #2255 |
Trades off accuracy (only gets to +/- 1MHz) for reduced code size as it doesn't need 64 bit division
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Fixup for dividers 1.0-2.0 on RP2040 Improve docs
That's better than the normal clock_configure, which only lets you overclock to 4.3GHz 🤣 |
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@kilograham do we want this function, or should I close this PR? |
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no, it is good; i didn't look in detail at the accuracy; does it at least get you near to the right answer, vs 1Mhz away ;-) |
If the divider is an integer (ie |
| uint32_t actual_freq = (uint32_t) ((((uint32_t) src_freq_mhz) << CLOCKS_CLK_GPOUT0_DIV_INT_LSB) / div) * MHZ; | ||
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| clock_configure_internal(clock, src, auxsrc, actual_freq, div); | ||
| // Store the configured frequency |
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What does this comment mean? (and is it referring to the line below or the line above the comment?)
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I’m not entirely sure (it was copied from the function above) - it’s related to the line above it as that’s what stores the configured frequency
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Perhaps it'd be less confusing if the comment was moved above the line it's referring to, as is done conventionally? 🙂
This adds a
clock_configure_mhzfunction, which trades off accuracy compared toclock_configure(only gets to +/- 1MHz) for reduced code size as it doesn't need 64 bit division.It takes the source and target frequencies in MHz as 16-bit numbers, to ensure they fit within the 32-bit division.
This is useful for example if you want to calibrate the ROSC using an XOSC and then run off the ROSC, in which case you don't need a very accurate frequency as the ROSC frequency isn't accurate.