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Measuring 30b CPU speed reduction
08-09-2015, 10:14 AM
Post: #8
RE: Measuring 30b CPU speed reduction
(08-03-2015 05:05 AM)cyrille de brébisson Wrote:  So, if the calculator runs for more than 1s at full speed, a timer kicks in and reduces CPU speed to 4Mhz (from memory). At that speed, the CPU runs on an internal oscillator which is very power friendly (compared with the PLL used at 30Mhz), AND the wait state of the flash can be reduced to 0 (instead of one, which speeds up the CPU calculation compared with the CPU speed).

This reduces the power consumption by a factor much greater than the ~5 time drop in CPU speed (around 10 if my memory serves me well) and places the batter draw back in the 'long pulse' range, drops the battery internal resistance (which means that battery energy will be used by the CPU and not to heat up the battery), and in turn increase battery life...

So, as I understand - after 1 sec continous running::
1.) The CPU speed reduced from 30~36MHz to 4MHz (factor_1: 1÷(7.5 ... 9))
2.) CPU calculation speed increasing (wait state reduction) (factor_2: (5 ... 10) ???)

The second point factor_2=(5 ... 10) is the factor of power consumption increasing or this is the factor of speed increasing (please translate your explanation to the simplified English Smile )

Csaba
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RE: Measuring 30b CPU speed reduction - Csaba Tizedes - 08-09-2015 10:14 AM



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