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Let’s start with Pin 1 on the D connector.
- PRO Rev 1 boards, Pin 1 (and pins 14, 16 & 17) are NOT used, however these pins are available via solder pads, near the 25-Pin D connector. Most often these are used as ‘output’ to drive spindle control relays, mist/lubricant pumps, etc.
- PRO Rev 2 boards, similar with ONE exception: pins 14, 16 & 17 are NOT used, and these pins are available via solder pads (these pads are on 0.100″ spacing, so a standard pin-header can be used), near the 25-Pin D connector. Difference – Pin 1 can be either a generic output OR you can add a small ‘solder-blob-jumper’ to turn this into an enable signal.
I’d never considered using them for step and direction. Since these signals are “inside” the control box, between a computer and the PRO board, I’ve never even suggested putting opto’s there.
Where I do recommend opto isolation, is anytime a wire leaves the safety of the control box (particularly limit and home switches), where there is a possibility of induced noise or (worse) a high voltage being applied on accident.
See my post: To Shield or Not To Shield (your wiring)
- This reply was modified 3 months, 1 week ago by BrianV.
Thanks Richard, yes, this is the right answer. Step and direction signals route directly to the chip from the 25pin D connector.
As long as you keep the voltage to those pins at 5V (I’m pretty sure they work with 3.3V too).
Although it’s for Arduino, you can probably get some info from here: https://hobbycnc.com/hobbycnc-and-arduino/
Here’s everything I know:
p.s. if you learn anything else, please do let me know and I’ll update the page!
Microprocessor I/O pins are quite delicate. They are not designed to string long wires from them into the ‘real world’, especially if there is ANY chance of ANY voltage getting applied to that wire. I always use opto-isolation on any/all inputs and driver chips (like a ULN-200X) on all output pins.
“The Arduino input impedance of an ADC (analog-to-digital converter) pin is specified as 100 megohms.” (source). This is ripe for any noise on that line to damage the input, quickly and easily.
Not sure why you’re using ADC for a probe. Typically this is just a switch input, like any limit switch.
I would not exceed a few inches on any wire connected directly to a microprocessor input, and if I went longer, I’d be double-damn sure they’re not running near anything that could pump electromagnetic noise into the wire (like, say, the wiring that carries the current to the stepper motors.
You need to put some isolation/buffer/driver between all I/O pins and the real world.
Method #3: Apply Overvoltage to I/O Pins
Apply a voltage exceeding 5.5V to any I/O pin. The I/O pin is destroyed.
This method of destruction forward-biases the ESD protection diode built-in to the microcontroller. Here is a model of each microcontroller I/O pin from the Atmel ATmega328P datasheet:
Once the voltage at the I/O pin is greater than the supply voltage (5V) by about 0.5V, the top diode starts to conduct current. This is OK for diverting a short-duration overvoltage event, like ESD (electro-static discharge), but that diode is not meant to be on all the time. It will simply burn out and stop protecting the pin.
I contacted Dave, and he never had plans for a foam cutter. He did at one time sell plans for a hobby router, but he’s since sold the rights to that.
So, I’ve got nothing for you regarding plans for a mill or foam cutter.
If you do need manuals for old HobbyCNC boards, check out the FAQs (under “support”) and scroll to the bottom.
Don, I don’t see any photos.
Under normal operation, the heatsink will get too hot to touch for more than a few seconds. This is why a fan is recommended for 2A or more (I’d put a fan on it regardless, but that’s just me).
Here’s where I point everyone when there is a problem:
The HobbyCNC boards haven’t had the timer feature for quite some time.
Unfortunately, I can’t help you with answers regarding the GMFC software – you’ll need to ask them what work-arounds they suggest. The USB/Ethernet to parallel port devices I’ve see are all software-dependent, so what works with one CAM system likely won’t work with another.
Sorry, but I’m sure the GMFC folks (or perhaps the website) can give you an answer.
Well, there’s not really a lot of things that can go bad, and there’s not really a lot of diagnosis that can be done either.
I’d have you start at the FAQs
If it’s a bad chip, email me brian at hobbycnc dot com and we’ll work it out.
Well, that isn’t the proper way to wire the switch. It is behaving exactly as I’d expect it to (e.g. it will do nothing).
The e-stop switch needs to be connected at one side to the GND of TB5 and to one of the remaining open pins on that same connector (Pin 11, in your case). The pin needs to be pulled to ground, not V+ (it’s already at +5V).
Another option is to put the e-stop switch in the same chain as the limit switches. See FAQ Home & Limit Switches. Regardless if it is a limit-reached or an e-stop, you want everything to stop moving.
You could go the relay route, but I think it’s overkill.
The old forum is still available for reading: https://groups.yahoo.com/neo/groups/HobbyCNC/info.
I’m not familiar with the 4AUPC boards, but I’ll give the drawing a look-over.
There should be plenty of inputs as-is.
ALL limit switches are wired in series (out of one, into the next) in a daisy-chain manner and all go to one input on TB5. It doesn’t matter WHICH limit is reached, you want to stop everything NOW.
That still leaves 4 inputs – one for Z-home, Y-home, X-home (and A-home if you have it).
The board already provides 10k pullups to +5V. Other than that, nothing is done to those 5 signal lines.
I’ve attached a schematic if that helps in understanding. Let me know if you need more info!
Hey David, thanks for the feedback/followup. and thanks for the kind words!
Would you be good if I used your quote on my webpage:
Your CNC router plans are nicely written, easy to follow, and comprehensive.
So far, the best plans I have purchased on the DIY CNC market today.
I have purchased five sets of plans so far, and yours are the best.
– David P
1 user thanked author for this post.
Look at the attached, starting on page 18. The spring is ‘pinched’ between the coupling nut and the square nut. Thread the rod through the square nut, slide on the spring, then thread into the coupling nut. Make sure the spring is compressed.
Something I’d fishy in Denmark. I’ll have to draw it out, but no way, no how can it cause any problems with the computer!
Till I can noodle on it, see if the resistor pack by those pins is in the correct orientation.
I’m going to assume an EZ board. Crude drawing attached.
There is nothing but a pull-up resistor.
As a matter of personal preference, I use the NC side of limit/home switches. That way, any switch, wiring or connectors that fail usually will fail open (e.g. fail safe).