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Fix headings mark

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Signed-off-by: Ludovic Vanasse <ludovicvanasse@gmail.com>
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Ludovic Vanasse
2024-10-12 14:18:34 -04:00
committed by Xiang Xiao
parent c13600a91f
commit 205ce38542
1 changed files with 9 additions and 9 deletions
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Documentation/guides/changing_systemclockconfig.rst
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@@ -8,13 +8,13 @@ Changing the System Clock Configuration
Question Question
-------- ========
`Is an STM32 configuration booting with the internal 16 MHz clock, then `Is an STM32 configuration booting with the internal 16 MHz clock, then
switching later (on command) to an external 25 MHz xtal doable? I don't think switching later (on command) to an external 25 MHz xtal doable? I don't think
so, but would you mind confirming that?` so, but would you mind confirming that?`
Answer Answer
------ ======
Of course, that is what always happens: The STM32 boots using an internal clock Of course, that is what always happens: The STM32 boots using an internal clock
and switches to the external crystal source after booting. But I assume that and switches to the external crystal source after booting. But I assume that
@@ -23,7 +23,7 @@ you mean MUCH later on, after initialization.
Yes that can be done too. There are only a few issues and things to be aware of: Yes that can be done too. There are only a few issues and things to be aware of:
Custom Clock Configuration Custom Clock Configuration
'''''''''''''''''''''''''' --------------------------
The ``configs/vsn/`` configuration does something like you say. It skips the The ``configs/vsn/`` configuration does something like you say. It skips the
initial clock configuration by defining initial clock configuration by defining
@@ -69,7 +69,7 @@ is no long in at config/vsn. The retired code can still be found in the
`Obsoleted repository <https://bitbucket.org/patacongo/obsoleted/src/master/nuttx/configs/vsn>`_. `Obsoleted repository <https://bitbucket.org/patacongo/obsoleted/src/master/nuttx/configs/vsn>`_.
Peripheral Clocks Peripheral Clocks
''''''''''''''''' -----------------
The peripheral clock used by many devices to set up things like the SPI The peripheral clock used by many devices to set up things like the SPI
frequency and UART bard rates. Currently, those peripheral clock frequencies frequency and UART bard rates. Currently, those peripheral clock frequencies
@@ -121,10 +121,10 @@ was done for the SAMA5D4-EK when you change the frequency too. You could also
make the peripheral clocks variable. make the peripheral clocks variable.
Reinitializing Peripherals Reinitializing Peripherals
'''''''''''''''''''''''''' --------------------------
Variable Peripheral Clocking Variable Peripheral Clocking
^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ----------------------------
If you did something like what was done for the SAMA5D4-EK when you change the If you did something like what was done for the SAMA5D4-EK when you change the
frequency, then the peripheral clocks would be variable. The main problem would frequency, then the peripheral clocks would be variable. The main problem would
@@ -139,13 +139,13 @@ methods to recalculate I2C and SPI BAUD divisors. But there are also memory
card frequencies and more. card frequencies and more.
Systick Timer Systick Timer
^^^^^^^^^^^^^ -------------
If the CPU frequency changes, you would have to change the Systick timer If the CPU frequency changes, you would have to change the Systick timer
configuration: It is always driven by the CPU clock configuration: It is always driven by the CPU clock
up_mdelay up_mdelay
^^^^^^^^^ ---------
up_mdelay() provides a low level timing loop and must be re-calibrated for up_mdelay() provides a low level timing loop and must be re-calibrated for
anything that causes change in the rate of execution of that timing loop. anything that causes change in the rate of execution of that timing loop.
@@ -154,7 +154,7 @@ are tolerable. Hopefully, you could keep the execution rate close enough that
up_mdelay() would not be grossly in error. up_mdelay() would not be grossly in error.
Power Management Power Management
^^^^^^^^^^^^^^^^ ----------------
This is also the same kind of thing that you would have to do if you wanted to This is also the same kind of thing that you would have to do if you wanted to
switch clocking for power management reasons. NuttX does have a power switch clocking for power management reasons. NuttX does have a power