Forum Replies Created
-
Here is another reference discussion
“https://www.geckodrive.com/support/step-motor-basics/motor-wiring.html”
As best I can tell, it leads you to the same endpoint as the first posting, which is to float the center taps and treat them as 4wire motors.Once you have movement, you will have to experiment to determine the step angle(steps per revolution), assuming you can’t find a spec sheet.
I am having to make a lot of assumptions about your description and tinyG settings.
On the tinyG Gcode and settings, I assume you are using a Homing cycle on A axis to move the probe. Is Amin set as both homing and limit?
“Completing the circuit” as you describe above when homing cycle not running would look like a limit switch operation, if Amin is set as both homing and limit. A limit switch operating would cause tinyG to reset.
But grounding out the 3.3V supply would cause a reset as well, and from your description that is another possibility.On the electronics side, i suggested using an FET because they are high impedance devices and the switch action you are attempting to sense is either an open circuit(no contact with gel) or a 500K ohm conductor.
I have no idea what you might have access to.
In my junk box I have 2n7000 MOSFETs.
I would connect the Source to ground, the Drain to Amin and pull the Gate high thru a 10Megohm resistor. The connect the gel probe between Gate and ground.
When gel probe is open, the gate voltage would be 3.3V, the FET would be on, the Amin would be low.
when the gel probe is closed, the gate voltage would be 3.3*(500/(10500)) = .15v, the FET would be off thus the Amin would be high.
The 2N7000 operates as a high impedance inverting switch.See https://github.com/cmcgrath5035/G2core-DUE-External-Interfaces/blob/master/G2core%20DUE%20External%20Interfaces.pdf
As a use exampleUsing bipolar transistors is also possible but not as simple when dealing with high impedance elements such as your gel
OK, it sounds like you are back in operation.
It also sounds like you are developing one or more control programs.I assume you are aware of a special condition that exists in tinyG due to a hardware bug in the Microcontroller.
Writes to EEPROM, the non-volitile memory used on the controller, take a relative long time. To work around the bug, tinyG stops listening to the serial interface until the EEPROM signals that the write cycle is complete.
TinyG then issues a status response if you have your program watching the return stream.The issues does not appear if you manually key in parameter changes one at a time from a console like Coolterm. but dumping a string of commands all at once will likely result in some commands being missed or worse, causing partial writes or incorrect values to be written to EEPROM. There are also instances where the EEPROM refuses additional writes.
If you seek to automate parameter updates, the proper way is to send a parameter value the pause sending, waiting for a confirmation that the EEPROM has completed before sending the next parameter.Read this old, closed issue for hints https://github.com/synthetos/TinyG/issues/123
A useful way to look for EEPROM corruption is to Send $$ an observe parameter values. If you observe unrealistic or impossible values, or values tou would not have set, it is an indicator of possible EEPROM corruption.
Sending the $defa command will reset the EEPROM to the default values that are in the FW download(compiled in)
