Sun May 11 10:47:41 EDT 2014
The simplest way to calibrate seems still to use frequency output of
an oscillator driven with the set current. This is a measurement that
can be done very precisely on a uC.
So how to get it to oscillate? Seems like a 555 is approprate.
However, can it be done with just a LM324N since I have one already?
Now for the oscillator we can cheat: charge cap with set current, but
drive discharge directly from microcontroller. This way the frequency
is exact but the amplitude depends on the current.
Using a comparator input, this can be done in the PIC. How fast can a
PIC respond? Can the comparator out be used to drive the discharge
directly? It seems so.