In SX Microcontrollers, SX/B Compiler and SX-Key Tool, PJMonty wrote:

Kris,

I don't know why you want to fiddle directly with the trim bits, but whatever.  If you're confused as to what affect the trim bits have on the frequency (based on the differences in the datasheets), try writing a simple program that outputs a known frequency.  Measure the frequency with a frequency counter or O-Scope, modify the trim bits, and then see what happens.

If you don't have the equipment to do that, then use two SX chips.  On one, use an external crystal oscillator so you know it's running at the right frequency.  On that chip, write a small program that counts incoming pulses during a fixed time interval.  On the other chip, do what I wrote about in the previous paragraph.  By counting the number of incoming pulses during a fixed time (make it long enough to be useful) you can determine if the change in the trim bits made the SX output more or less clocks.  You can even figure out the specific time change for each of the trim bit choices.

Thanks,
PeterM

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