cmcgrath5035

jimtellier: You describe an odd (apparent) failure, indeed. Understanding your method of communications with TinyG might help. Could be a basic terminal window (putty, coolterm, etc) or a more complex interface such as chillipeppr. The serial interface on TinyG is a ftdi chip, it may be reporting ‘ok’ to your control computer without TingG FW actually running.
When connected, a tinyG reboot (button press or power cycle) should yield the TinyG prompt in a command window when FW initializes.
Homing Z axis was implemented by only a few users; do you actually have a limit switch installed at top of travel? Did Home to Z ever work? You might try disconnecting Z wires from TinyG to see if you can recover basic control
I (am supposed to) get a message from this Forum when someone posts; this is the first I have seen in over a year. There is occasional activity at https://github.com/synthetos/TinyG/issues , but not much.

There has been very limited activity in the past few year on tinyG.
You could post this question here, closer to whatever developer activity there is: https://github.com/synthetos/TinyG/issues

While there, have a look at the G2 project at https://github.com/synthetos/g2
g2was the next generation, might be a better fit to your needs

Good luck with your project

tinyG was born perhaps 8 years (or more) ago and focused on the DIY build your own 3 axis machine, which morphed quickly to 4 motor three axis machines. Many basic kits came out with no limit switches at all, then larger, more rugged designs came along as well. Any tinyG was used in many 3rd party machines.

Make sure you read this wiki item carefully
https://github.com/synthetos/TinyG/wiki/Homing-and-Limits-Description-and-Operation

Summary: G28.2 is hard coded to home to Zmax if it is enabled. It will not home to Zmin. If Z homing is used, Z home must be Y=0 and all z motion down must be negative. these are the assumptions used in tinyG.
G2core has implemented some flexibility. I believe (I am not a developer) the decision was made to minimize Z homing that dragged across the work piece.
ALso read theru https://github.com/synthetos/TinyG/wiki/Gcode-Support, see if your interpretation of G30 is same as Synthetos.

The Zmin switch, or Zmin input, is also used for automatic probing of the work piece.

Good luck with sorting this out, as you say it may just need a procedural workaround.

a resend to make sure I get notified of a response

This is likely a software/configuration issue, but yes, the endresult is hardware that works.

I recommend you post thas at https://github.com/synthetos/g2/issues, the G2 developers and many other hackers/customizers hand out there.
You make the shield in your design sound somewhat mysterious, home brew?
If it is a commercial part, identifying might speed a response.

Good luck with your project

You will not find exactly what you are looking for here at Synthetos.
Very early work on a version of what you might be looking for, the tgFX GUI, was put on the shelf when other projects like Chilipeppr and CNCJS got started.
If you scour the tinyG issues pages at https://github.com/synthetos/TinyG/issues you will see others like yourself working similar issues in both open and proprietary space.
Much of the intense work on Chilipeppr and CNCJS dropped off several years ago but the code is available for viewing, cloning and extending.
From your description of the task, it would appear to me that you are familiar with all the resources on Github and the Synthetos Web.

You are likely thinks about a 3D printer type application. TinyG will do whatever the G code tells it to do, but all motion will be subject to the jerk motion enhancement that seeks to maximize machine efficiency (time spent on the job). Some folks have used the A axis to coordinate some variation in extrusion rate.

You may want to research the G2 project somewhat, it is aimed at providing the motion foundation for 3D as well as 2D motion.
https://github.com/synthetos/g2/wiki
tinyG is rather resource limited (memory, CPU).