External Reset Button for GRBL Shield

Discussion about the arduino based g-code interpreter, grbl
MathewOwen
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External Reset Button for GRBL Shield

Post by MathewOwen » Sat Mar 16, 2013 9:00 pm

I am building an enclosure for my shapeoko electronics (I am using GRBL Shield), and would like to add an external reset button as the enclosure will prohibit me from accessing the board itself.

Please let me know if anyone here has had the same problem and how I might be able to attach an external reset button to my enclosure. It would be very much appreciated!

- Mathew
Mathew Owen - Proud owner of a ShapeOko @ Fab Lab San Francisco http://fablabsf.org/

ejs
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Re: External Reset Button for GRBL Shield

Post by ejs » Sun Mar 17, 2013 9:02 pm

Hi Mathew,

I've been playing with enclosure options for a year or so. For mine, I got a panel mount momentary with a rubber boot--in hope of keeping dust at bay. I drill a hole in the enclosure and tighten it up. The leads on the CNC shield reset button are long to start with. I leave them with about an eighth of an inch and solder the panel mount button's leads to the exposed pins underneath.

(BTW, sorry I keep adding the second T to your name.)

~EJ
Build it better than it was built for you. And give permission for the next guy to do the same. That's how Open Source works.
ShapeOko # 497: http://bit.ly/reactshop producing the Buildlog CNC Stepper Shield

mjohn
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Re: External Reset Button for GRBL Shield

Post by mjohn » Thu Mar 21, 2013 4:47 am

Might not be the safest, sanest or most elegant solution, but my external reset switch is hard wired into the GRBL v3 shield. I'm sure you can cross reference it if you have a different version. I too was scared of reaching in and hitting that GRBL reset every time.

Standard disclaimer: Not responsible for blowing up your GRBL, don't attempt if you don't know what you're doing.

Each wire goes to one leg of a momentary normally open switch. Pressing the button shorts the two pins. There's a resistor in line, doesn't matter which wire. Double check the value, I can't remember what I used and mine is heat shrinked. I could peel it back or meter it out if nobody else can come up with the value.

Image
John Milleker Jr. - Historical Process Photographer/Instructor
Baltimore Maryland, USA - http://www.JohnMilleker.com
ShapeOko #1,284 - Upgrades: 2x4Oko (24x48" footprint), Double X rails, Acme-Z, Dual Y, DW660, IC's Dust Shoe w/Dust Collection.

cvoinescu
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Re: External Reset Button for GRBL Shield

Post by cvoinescu » Fri Mar 22, 2013 4:00 pm

I'm not sure you actually need a resistor on the reset line. Just short the RESET pin to GND.

You could solder male headers in those holes, and use female connectors like the ones connecting PC reset and power buttons to PC motherboards. They can be bought cheaply on eBay, with or without wires crimped on -- for some reason, they're called "DuPont headers" by many sellers.

I can see a fine, reddish strand in the picture. Is that copper, or hair? If it's hair, in that color, it must look gorgeous where it came from. :)
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

Metroid
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Re: External Reset Button for GRBL Shield

Post by Metroid » Fri Mar 22, 2013 11:00 pm

I'm not sure you actually need a resistor on the reset line. Just short the RESET pin to GND.
You need a pull-up resistor of 4k7 - 10k if internally the pull-up's are disabled. If the internal pull-up's are enabled a extra set of resistors is not necessary, but can do no harm.
You can have a 100nF over the switch for filtering bad signals from motors, etc.
and use female connectors like the ones connecting PC reset and power buttons to PC motherboards
They are called crimp housing and connectors. Used on servo's, PC's, etc.

http://uk.rs-online.com/web/p/pcb-conne ... s/6812812/

You also need the crimp connectors inside.

Gr. Rob.
eShapeOko #92, 4x Stepper Shield, All in One GRBL
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edwardrford
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Re: External Reset Button for GRBL Shield

Post by edwardrford » Sat Mar 30, 2013 10:07 pm

cvoinescu wrote:....I can see a fine, reddish strand in the picture. Is that copper, or hair? If it's hair, in that color, it must look gorgeous where it came from. :)

If i'm not mistaken the fine reddish strand in the picture is the stranded strain relief from inside the 4 wire stepper cable :-) Unfortunate, but probably true.

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

turtle13
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Re: External Reset Button for GRBL Shield

Post by turtle13 » Fri Jan 31, 2014 8:09 pm

here is to resurrecting an old thread!
I have decided to run a screwshield to hook up limit/homing switches, do these correspond to a pin that could be easily hooked up through the screwshield?

cvoinescu
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Re: External Reset Button for GRBL Shield

Post by cvoinescu » Fri Jan 31, 2014 8:35 pm

You're looking for this chapter of the GRBL documentation.

In brief, connect normally open limit switches between D9 and GND for the X axis, D10 and GND for the Y axis, and D11 and GND for the Z axis. My advice is to add three pull-up resistors (say, 330 ohm, or anything between 270 ohm and 1 Kohm) connected between D9 and 5 V, D10 and 5 V, and between D11 and 5 V. They help reduce false triggering caused by electrical noise.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

turtle13
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Re: External Reset Button for GRBL Shield

Post by turtle13 » Fri Jan 31, 2014 9:15 pm

sorry i should have been more specific. I got a screw shield for the limit switches, can the reset also be hooked up through the screwshield via pins on the screw shield?
#edit#
so correct me if i am wrong, but for an external reset switch, I would simply run a momentary switch between A0 and ground?

cvoinescu
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Re: External Reset Button for GRBL Shield

Post by cvoinescu » Fri Jan 31, 2014 9:26 pm

That's the GRBL reset; you can use either that one, or the RESET pin. They do different things, but I don't know how the A0 pin works exactly. I think people wire that into the emergency stop button.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

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