As the brushes ware through use, these spindles get louder and louder on the EMI front and so you may notice limit switch issues creep back into your system in 6 months from now and wonder why after 6 months of beautiful work its happening again?

There are thresholds within which we assume High and Low. I've converted a small SL1000 lathe to CNC using an Arduino and GRBL shield Also seems that you get a little more protection against broken wires.

This allows UNO do what its suppose to without any other special stuff like shielded cables etc. It’s also not so small that moderate levels of noise can overpower it and cause trouble.Note: If you do decide to add extra pull-ups to help charge the cap, when doing your calculations remember that the resistor your adding is in addition to the pull-up resistor inside the microcontroller. Reply (These are pins 9,10 & 12 in Arduino Talk)When you hit a limit switch, the limit switch connects/shorts this pin to ground causing the voltage on this pin to rapidly drop from High State (5V) to Low State (0V/GND).

You are receiving this because you are subscribed to this thread. There are two ways of doing this, which are physical filters and debounce management.

1 year ago It does this to set a default known 'all good’ state for the limit switch pins.

1 year ago 8 months ago

Once a limit switch is triggered, the spindle is automatically stopped and the woodpecker board goes into a locked state to prevent any damage from occuring.

There is hopefully enough buffer in the cap to ensure the relatively weak EMI noise currents induced into your limit lines cant pull it down hard enough to cause it to drop below the 0.8V threshold.Placement, it should be done as close to the controller as possible.The size of the capacitor is important.

Installed a new CNC shield V3 onto a new Arduino Uno and verified it was installed correctly . No resisters were used. Debouncing solves reading a signal jumping up and down too quickly not one that’s taking too long to come back up.We have found that 0.47uf is a perfect value, as it is not so big holding so much power that it ruins switches or itself when shorted to ground. (With NO Mode)The X Controller is just an Arduino at heart, and Arduino is Just an Atmel 328P microcontroller.

I really appreciate you taking the time to help me out. Just as you described all is well until I turn the spindle motor on or off.

IE requiring a strong pull-down like being shorted to ground by you’re limit switch being pressed.

can all also generate EMI noise for your wires to collect and ruin your day.A really common one is your shop vac!

Nice to know.This limit triggering issue seems to have been problematic for some people for a long time.

It does this to set a default known 'all good’ state for the limit switch pins. After that, I did not notice any (this is not a waste of power / creator of heat, capacitors average consumption not add) The internal pull ups will ensure that the cap cant draw to much current on initial charge from the atmega pins so there is no safety issue for the arduino. This noise is picked up by your limit switch lines, which are very effective antennas to collect the noise and direct it into the micro controller's pins. From ShapeOko.

However, in your case, these other lines apart from the probe have very short wires between the controller and the buttons/switches, they are all also internal to the alloy box which provides some shielding. I wanted a target switch detection time of between 1 and 10 milliseconds, i.e. Just follow the same wiring setup for the first switch with the second switch. Thanks for sharing!Maybe to much to ask but would some tech be so kind and add Z-probe to this board? The new version has hardware ENABLE protection - after power up the Enable signal stays non active for 1.5s (independently from Arduino board) to avoid spontaneous motor movement. In come the Caps and Resistors.By putting a capacitor between ground and the limit switch line, we are giving it a bit of a buffer charge and requiring a much stronger pull down to the ground in order to fully discharge the capacitor below the 0.8 V threshold that will be picked up as a logic low.

Reply to this email directly, view it on GitHub

This is true for all occasions except for during a homing cycle - which is obviously the only time that hitting a limit switch is an expected and planned event.Another important note is the 0V vs 5V logic is not really the truth.

— But I will outline the theory and fix in as simple words as possible and you should be able to work it out from this. With the connection of circuit breakers no problems In this way it’s almost the same as what we have done on the AIO.

Ben, i can't believe Ithat you took the time to write such a comprehensive and detailed explanation! You are receiving this because you are subscribed to this thread. When the switch is closed, the capacitor will be charged by the constant current.

Reply

It’s also not so small that moderate levels of noise can overpower it and cause trouble.Note: If you do decide to add extra pull-ups to help charge the cap, when doing your calculations remember that the resistor your adding is in addition to the pull-up resistor inside the microcontroller.