I'm building a new hardware version of my device. Previously, I used TinyG hw ver7, and I think I used firmware build 392.65. fast forward a few months, and I now have better hardware, and TinyG hw ver8. For noise issues, I'm using NO double throw switches - there is more threshold from 3V to logic low than there is from 0V to logic high. Because of NO switches, I went back to 392.65.
The issue I'm seeing is probing on Z. With G28.4 commands, probing on X and Y work, as does probing Z up ($zsx=2, $zsn=3, the regular settings). But when I probe Z down ($zsn=0, $zsx=1, g28.4 z0) it does not work, but tries to push the probing needle to the work piece.
The thing that baffles me is that the hardware switch does actually work, TinyG panics if I activate it with normal settings. So, it is not a hardware issue. But it is not a software issue either, because it used to work with my previous setup. Obviously, one of these is not correct, but I've run out of ideas.
Any insight where to look next?
Although I'm not 100% sure about the v7 software, I've tried all versions that I have, and certainly, one of them used to work. It would be a big effort to go back to the old card; besides, I need to get this working with v8.
I.m not sure why you went back (from?); tinyG FW supports NO or NC switches.
Anyway, tinyG build 435.10 has a whole bunch of fixes and tweaks, including a new G38.2 Z probe command. I'd suggest moving to the new build, as there will be no support for the older builds moving forward.
Read up on the wiki - there are several new config parameters you should be aware of, and the initial load may not match your setup.