Author Topic: GBRL why the mystery?  (Read 3293 times)

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Online langwadt

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Re: GBRL why the mystery?
« Reply #25 on: December 30, 2020, 01:21:05 pm »
I will be doing a PCB with a keypad that talks to the machine over a serial port so that I can control it. That's all. but when you read the information from the source that talks about any speed over 115kbps the natural question is OK so surely that is a synchronous port? all this basic stuff is not explained on github because that was all written for the arduino which is a complete implementation of USB to serial to GRBL on a specific peice of hardware - the Arduino.

I assume things have progressed somewhat, a few years ago I sold a guy an ATMega328, I usually sold them blank or with a 8MHz or 16MHz Arduino bootloader flashed in. This guy wanted something specific which I did as a one off favour as he did not have a programmer or know how to do it he just wanted to make a controller for his CNC machine and it had something to do with Arduino but with an alternative bootloader. So I don't know if there was a time when rather than be an Arduino library it was an Arduino hardware compatible program so that off the shelf boards could be used by people like this chap that was more interested in CNC than electronics but was willing to dabble.

GRBL is not and has never been arduino, it's plain C that just runs on arduino HW and you can program the HW via the arduino IDE

I don't understand the confusion over the serial port. GRBLs interface to the world is the AVR UART, default is 115.2kbps but you can program
it to any baudrate you like.
 

Offline phil from seattle

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Re: GBRL why the mystery?
« Reply #26 on: December 30, 2020, 08:21:50 pm »
The Grbl Wiki (that I pointed you to) has a fairly extensive section about interfacing to Grbl and how to keep it running smoothly while feeding it GCode.  So, to answer your "I just want to use it" question, look there.

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Nice board you have made there Phil
  Thanks!

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the answer is always "read the code" why should I have to do that?
Well, in a perfect world the developer would have put the effort in to equal the amount of effort that the professional product developers did.  So, no, you shouldn't have to. Bunch of good-for-nothing, lazy FOSS developers. What's the world coming to??? :-DD

 

Offline Simon

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Re: GBRL why the mystery?
« Reply #27 on: January 03, 2021, 11:56:21 am »

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the answer is always "read the code" why should I have to do that?
Well, in a perfect world the developer would have put the effort in to equal the amount of effort that the professional product developers did.  So, no, you shouldn't have to. Bunch of good-for-nothing, lazy FOSS developers. What's the world coming to??? :-DD



Yes of course but when you have to read the entirety of the code to figure it out you end up in a position where you may as well write it yourself which is where I ended up with micro-controller manufacturer middleware where to use what the manufacturer gives you you need intimate knowledge of the chip anyway and to reverse engineer the code (read it all and see what it does) at which point it's easier to write my own as I study the the datasheet of the part. Obviously something like grbl is more complex but there is this tendency to "be clever" and then not explain it when it comes to programmers. It's the same reason why Linux will never take hold even if it's better than windows, we can all (within reason) use windows as it's made for the non technical user unlike linux.

Presumably open source projects are therefore about just showing off to your peers.

My machine has arrived. The frame is built up although they missed some of the nuts that slide into the extrusion to mount the controller so will see if I can get those before powering it up as I'd rather mount the controller properly. The controller is based on an ATMega328. Strangely it claims two Y axis outputs but I assume these are simply parallel connectors for motors that will be driven together either side of a frame.
 

Offline Simon

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Re: GBRL why the mystery?
« Reply #28 on: January 03, 2021, 02:08:04 pm »
No I don't want to make this a linux versus windows thread and I am talking about the types of people that use them rather than the platform itself. I also meant just the two OSes not the possibility of commercial offerings on Linux. And of course often hidden behind the "free" is a commercial interest. When I started with hosting I tried Vesta cp, oh wonderful, free. But there was a bug after an update that apparently was well known about and with some difficulty I got help to resolve the issue with software that I was being told was wonderful and free but was known to have a bug that needed a file editing with a text editor on update. When I was faced with further problems and with an unhelpful "support" forum I was offered commercial help to the tune of £100 for an hour or two. For less than that I can rent cPanel that broadly works out of the box and has some support. Obviously if I was deeply knowledgeable about Vestacp and doing largescale hosting it would pay for me to invest the time in learning it inside out given the huge savings in cPanel licensing which is what some actual hosting companies do, but this is out of reach of little old me that just wants to host a few sites for friends and it's easier to pay what vestacp support costs by the hour for an entire year of trouble free software operation.
 

Offline Simon

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Re: GBRL why the mystery?
« Reply #29 on: January 03, 2021, 02:12:00 pm »
With the dual Y axis drive it is just a cheap and dirty way of doing it to put two same axis motors in parallel. There is 1 X socket, 2 Y sockets and one Z socket, but each axis is driven by an identical plug in driver so clearly it's just two sockets in parallel as if the driver was truly dual channel then only two drivers would be required for the 4 sockets. As things stand with this machine it's only one Y axis so the question is just academic.
 

Offline phil from seattle

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Re: GBRL why the mystery?
« Reply #30 on: January 05, 2021, 07:58:05 pm »
Yes, at the bottom end of the CNC market the Chinese Grbl based controllers only have 3 axis outputs and thus a ganged motor axis simply takes the Y Axis output and shares it with 2 drivers.  For those little stepstick stepper drivers, it's not the end of the world.

Sadly, this makes auto-alignment impossible for a ganged Axis machine. Manual alignment isn't terribly hard but it is a bit tedious. There are breakout boards that support auto alignment though.
 

Offline LaserSteve

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Re: GBRL why the mystery?
« Reply #31 on: March 05, 2021, 09:37:01 pm »
Has any one here ever demonstrably done single axis homing in GRBL?  I love it, but I have struggled making a single axis configuration that homes without crashing.

Steve 
"I've Never Heard of a Nuclear Meltdown Caused by a Buffer Overflow"  filssavi
 

Online langwadt

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Re: GBRL why the mystery?
« Reply #32 on: March 05, 2021, 09:45:22 pm »
Has any one here ever demonstrably done single axis homing in GRBL?  I love it, but I have struggled making a single axis configuration that homes without crashing.

Steve

what did you do? it works just fine, in config.h define HOMING_CYCLE_0 as the axis you want to home, don't define HOMING_CYCLE_1 etc.
 


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