Can you provide more context?
GCSR controls the peripheral clock. I’m not sure what the power up default is, but it probably isn’t important since the BIOS is going to change it before your program starts.
You can look at the BIOS source to see how it sets GCSR, or likely read GCSR or GCSRShadow in your program to see the current setting.
From my quick read, it looks like it might default to using the main oscillator clock and be identical to the CPU clock.
Does that answer your question? How does knowing the default frequency affect how you’re going to write your code?
I want to know how high a pulse rate can be decoded on the quadrature inputs. We have a 2500 line encoder spinning at 3000 RPM. That gives us a 125Khz signal. PERCLK is the signal that clocks the quadrature decoder and filter.
The current motor has a 1000 line encoder and works fine.
I think I will just simulate the 125 Khz signal and see if it can keep up. If it is CPU clock rate it will be fine.