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Sorry for the super-late response. Not sure how I missed your post!!!
1. I appear to have a Rev 1 board. Is there any way that I can run a jumper to some part of the HobbyCNC Pro 4 circuit from this pin so as to gain the Enable-pin function?
A: Yes, but some parts need to be removed and some jumpers added and some traces cut.
I just documented the process here: https://hobbycnc.com/pro-rev1-enable-signal/2. Is the Enable pin on the Rev 2 board an input or an output?
A: Input
3. I like to provide isolation between different power domains whenever possible. My concern here is that I would like to limit the damage if, for some reason, one of the SLA7078MR chips were to fail. By using optoisolators, I limit the damage to the HobbyCNC Pro 4 in that eventuality and protect the controller board from damage. Since my controller board requires me to make an adapter card, this would be an opportunity to put optoisolators on all signals to/from the HobbyCNC Pro 4 as well as on all limit-switch, home switch and tool touch-off points.
A: There’s a lot to unpack here.
PC to HobbyCNC board. Although possible, I’ve never run across a reason why to do this. Unlike the Inputs (TB 5), these signals are all contained in a single bundle from PC to board. Very little (none?) potential to add goofy voltages here.
Inputs (TB 5). I’m a fan of this since the “inputs” (e.g. limit switches, probe, e-stop, home switches) are “outside” the safety of the electronics enclosure, and anything can come in contact with these wires. I think opto isolation here is a good idea. Remember, a completely separate, isolated power supply is required. I especially recommend opto isolation here if there are ‘false triggers’ of limit switches, etc.
Outputs to Stepper Motor. This is not something that can be done.
4. How much power, if any, can I draw from the +5VDC pad? I could mount a heatsink on the LM317. Would it be preferable to use a separate regulator for my adapter card?
A: I prefer you don’t tap into the +5V line. Since that regulator needs to drop from 24 to 5 V, it can need to dissipate a LOT of power. It’s designed to just power the circuitry on the board.
Details here: https://hobbycnc.com/sp_faq/checking-voltages/Regards, BrianV
Peter,
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.
The optoisolation:
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)
BrianV
Thanks Richard, yes, this is the right answer. Step and direction signals route directly to the chip from the 25pin D connector.
https://www.semicon.sanken-ele.co.jp/sk_content/sla7077mprt_ds_en.pdf
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/
BrianV
Here’s everything I know:
https://hobbycnc.com/hobbycnc-and-mach3/
Regards, BrianV
p.s. if you learn anything else, please do let me know and I’ll update the page!
Dear Jacques,
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.
From: https://http://www.rugged-circuits.com/10-ways-to-destroy-an-arduino
—————————————————
Method #3: Apply Overvoltage to I/O Pins
HOW
Apply a voltage exceeding 5.5V to any I/O pin. The I/O pin is destroyed.WHY
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.
—————————————————BrianV
Keith,
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.
BrianVDon, 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:
FAQ: No Motor Movement
FAQ: Missing steps – motor not behaving properlyFAQ: Microstepping Configuration
FAQ: Product Manuals / Assembly Instructions
FAQ: Is a special cable required to connect to my PC?
FAQ: What Power Supply do I need?Don,
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.
Regards, BrianVWell, 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
https://hobbycnc.com/sp_faq/no-motor-movement/
and
https://hobbycnc.com/sp_faq/missing-steps/
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!
BrianV
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 P1 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.
DIY-CNC-Router-Plans-HobbyCNC no drawings.pdf
BrianV
