It's my understanding that after pondering pros and cons, the Sampling ADC development has been put on hold for m-firmware. So looking at the quartz crystal measurement options for this, I have some comments about the documentation:
Section 3.1.12. Frequency Counter of CTester 1.51m doc points: "The circuit diagrams for both are depicted in Karl-Heinz’ documentation."
However, on TTester 1.13k (2021) doc I notice the basic frequency measurement circuit, but not what referred from 1.51m doc.
And back to 1.51m doc, I think 3.1.13 and 3.1.14 are both the options of 3.1.12, so IMHO those should be 3.1.12.1 and 3.1.12.2.
Anyways, I looked at the schematic of the Hiland M644, and I notice the implemented (extended) hardware option. Could that be ported to an smaller MCU?
It's not like I'm testing xtals everyday, but anyways I know the workaround: to have k-firmware handy.