Hi all,

An interesting observation arose for me just now whilst cutting the code on
an f877 to do the A/D for current sensing from a device being controlled
from a PWM voltage source.

My PWM is at 5kHz.  I discovered that the current readings were not
averages, because the A/D acquisition time is much faster that the PWM
frequency, so the current sense readings were sometimes coming back as
maximum, and sometimes as zero !  It is obviously catching either the low or
high state of the PWM output.  Only occasionally were they coming back
somewhere in between - obviously when the A/D acquisition happened to catch
the PWM on a rising or falling edge.

My simple solution was to take a number of readings and average them.  In
this case, I took 20 readings, which seems now to give me a good "average"
current output, which is what I was after.  Any comments on better ways to
do this would be appreciated.

Rgs
Ian.

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