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docs: Update timer tutorial to reflect new behaviour of timer.

This commit is contained in:
Damien George 2015-02-23 22:14:54 +00:00
parent 5d323defe4
commit 1babb6d0c7
1 changed files with 6 additions and 4 deletions
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10
docs/tutorial/timer.rst
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@ -26,12 +26,14 @@ it's not yet initialised. So let's initialise it to trigger at 10 Hz
Now that it's initialised, we can see some information about the timer::
>>> tim
Timer(4, prescaler=255, period=32811, mode=0, div=0)
Timer(4, prescaler=624, period=13439, mode=UP, div=1)
The information means that this timer is set to run at the peripheral
clock speed divided by 255, and it will count up to 32811, at which point
it triggers an interrupt, and then starts counting again from 0. These
numbers are set to make the timer trigger at 10 Hz.
clock speed divided by 624+1, and it will count from 0 up to 13439, at which
point it triggers an interrupt, and then starts counting again from 0. These
numbers are set to make the timer trigger at 10 Hz: the source frequency
of the timer is 84MHz (found by running ``tim.source_freq()``) so we
get 84MHz / 625 / 13440 = 10Hz.
Timer counter
-------------