A new wrinkle today in the ongoing saga with Tinyg/Chillipeppr/ Json i.e.
As usual when homing the router the Z axis freezes in full top position but this time the Z readout indicated minus 22.195 mm(-.874 in.), perhaps it is time to chuck these controls and move on to something that may be out dated but seems to be very popular even this digital age
I wonder if you’re having the same issues I’ve been having with trigger detection on the TinyG. I’ve found that sometimes when the limit switch or probe is triggered it ends up in an invalid state because of a very fast trigger release.
Also Billy I know homing seems like a really useful thing if you’re coming from the 3d printer world, but in CNC land its not as common as you might think. More often you are probing to find the edges of your stock and using coordinate systems to set zero points around your work piece, so homing is less valuable in these operations.
Perhaps try switching to CNCJS (https://github.com/cncjs/cncjs/wiki) its a bit more stable than Chillipeppr I have found, especially on long jobs, though it does lack some features like probing for bed levelling offsets.
https://github.com/cncjs/cncjs/wiki
Limit switches if wired incorrectly can introduce some noise… There are many instances where you need either a pull up or pull down resistor to make sure the limit switch actuates properly
I see lots of reports of noise regarding noise on these switches.
Input Configurations:
On the tinyG (at least) the switch inputs have 2.7K pull-ups tied to 3.3V with .22 uf filter caps to ground.
On smoothie compatible config switch inputs there is a 1K pullup tied to 5v and a series 5K and .1uf cap input filter.
These inputs are connected directly to the processor and although I would have liked to have seen a Schmidt trigger buffer these inputs should theoretically work.
Problem Source
My guess is that due to long wires there is noise coupled onto those lines. I hope the firmware filters the switch bounce?
Design and practice hints
Some suggestions that I will verify as I complete my large OX build. [stalled due to gran-kids visits]. I do not yet know if I have noise problems.
Grounding is important and often the underlying culprit. Grounds (both signal and power) should return from the destination to the source directly… not any other ground.
Wires to the switches should go all the way from the controller to the switch. Don’t wire one wire to the switch and use the frame to complete the circuit.
I have heard that sometimes NC or NO configurations work better. The controllers config must match the NC/NO wiring choice.
Single point grounding should be employed at the power supplies to the frame and safety grnd.
Wiring the switches using at least twisted pair or at best shielded wire. I used CAT5 cable. With sheilded wire the location of the shields ground may vary. Sometimes signal ground, frame and open works.
Route the end-stops away from motor cables and as much as possible keep them out of the same bundle. However the final cable chain loop includes all cables so minimize its length. You could also run two loops although I am not convinced this is necessary.
More pull-up current could help but sometimes more current makes the problem worse. Start by putting additional filters on the end stops. Either at the switch or at the input to the board. You may have to experiment with location or how the cap is grounded. I would try .01 uf to signal or frame ground.
If all this fails we could add a filter breakout board but lets not go there yet.
Just some ideas from my experience… hope they help.
Don, thanks very much for your detailed advice and observation, you touch on some points that I have considered such as wiring/noise which I long last I will look into further, also Don would you mind perusing my tinyg cinf. listed elsewhere on this page.
@Billy_Lester is the config on this post or another?
I can look at it but I am a novice at tinyg as I just got mine wired. I am normally a smoothie user.
Don look on the google+ home page for the data I referred to.I noticed that each time I bring up chillipeppr the image I tried to carve re- appears, do you know if chillipeppr can be purged?