XStepper: New complete Hardware GRBL solution.

[xpix]

Update:

This Project is close to realized and has renamed to XStepper. If you need actual informations, please visit this links:

http://www.shapeoko.com/wiki/index.php/XStepper
https://github.com/xpix/XStepper

cu
Frank(xpix)

Hello,

i want to create a box with some Arcarde Buttons for feed Hold and so on ...

My Problem is, i have only the Buildlog Stepper Shield. It is difficult to connect the wires at the right place. In this moment i decide, maybe it's better to design a new Stepper board with all connects for spindle on/off, buttons and endstops.

Here is my first draft, the most elements are stealed from RepRap project. They use a Atmel mega ... in this example i use a normal 328:

https://guloshop.de/shop/Mikrocontroller/ATmega328-P::17.html

He use also a FTDI Chip for USB Connect ... this schema is close the same as Arduino + StepperShield + EndStop terminals + Spindle Terminal (Solid State Relais is planned)

First some points:

* It's only a draft, maybe you or you see some mistakes ... please let me know where
* at this time, i create only a schema in eagle, feel free to make a board with this data

As Attachment the Schema:

stepperX.zip

Draft for schema (eagle)

(29.66 KiB) Downloaded 230 times

Screenshot:

Screenshot

stepperx.png (33.16 KiB) Viewed 6147 times

[Godsplan]

Hey xpix,

i also tought about a new stepper board for grbl with a combination with arduino. I started sketching this like yours and want to produce a batch after development is finished. My target is to reduce the costs for arduino + buildlog shield + 3 or 4 A4988 stepper drivers. do you thought about using a cheap usb ftdi breakout from ebay instead of using an FTDI SMD part. it would decrease complexitity with soldering and price.

i will compare your sketch with mine and will build it on my breadboard. i let you know when it works

greets,
chris

[Godsplan]

shouldn't the reset momentary switch beeing connected as pull-up with a 10k resistor to Vcc?

[Godsplan]

hey here is my version. i used your atmega in eagle with your pin layout (thanks for that)

i added some elco capacitors to the 12 V supply at each pololu driver. i read that this will stabilize the running but i cant prove this (elcos are also cheap, so no i dont care).

Next i won't use an ftdi chip on the pcb because i dont want smd parts and a usb ttl costs only 3$.

So thats it, perhaps you have some tips or critics. its my first electrical draw, so please be toughtful:)

[cvoinescu]

If you make your own board, especially with a ready-made USB-to-serial adapter, separate USB GND and VDD from system GND and VDD, and use optocouplers on TxD and RxD (nice, fast optocouplers such as 6N137 with 470 ohm pull-ups and LED series resistors). You can add jumpers to allow USB and system ground and VDD to be connected, so that you can power your board from USB too, e.g. when flashing the firmware. If you keep the USB electrically separated when milling, it's much, much less likely to get disconnected when there's noise on the AC lines (e.g. an inductive load turning off, such as a vacuum cleaner or refrigerator compressor, or even the spindle). You'll love me for this advice when your long jobs won't get interrupted every ten minutes or so.

[Godsplan]

Thanks cvoinescu for your advice, i will try to integrate your solution and try how it works. but i have a few questions about this.

If you make your own board, especially with a ready-made USB-to-serial adapter, separate USB GND and VDD from system GND and VDD, and use optocouplers on TxD and RxD (nice, fast optocouplers such as 6N137 with 470 ohm pull-ups and LED series resistors).

Seperate txD and RxD wit a 6n137 is no problem, but how to isolate USB GND and "PCB GND" and also "USB 5V from PCB VCC" ?
do you realized this and would share it with us?

[xpix]

Hey friends, cool ideas sorry, at this time im in vacation (egypt i want to answer later, when im back.

The idea to separate tx and rx is nice, but why? The experience with arduino and buildlog shield tell another story ...


Sent from my iPhone using Tapatalk 2

[Godsplan]

i will definitly try to use a usb ttl converter from ebay but without the 5V, i will usethem from the power supply. you think this could work?

[cvoinescu]

The goal is to keep USB electrically separated from the rest of the system. That way, USB won't lose connection every time there's some electrical noise (which used to happen a lot to me, and I've read several similar stories here and on buildlog.net). I don't know what the root cause is -- other USB devices don't disconnect randomly, even devices with a separate power supply, and even with the same USB cable -- but galvanic isolation fixed it for me, and it never disconnected once since I did that.

About GND and VDD: simply keep the USB +5V separate from the board VDD, and the USB GND separate from the board GND. No electrical connection between USB and the board at all.

[Godsplan]

The goal is to keep USB electrically separated from the rest of the system. That way, USB won't lose connection every time there's some electrical noise (which used to happen a lot to me, and I've read several similar stories here and on buildlog.net). I don't know what the root cause is -- other USB devices don't disconnect randomly, even devices with a separate power supply, and even with the same USB cable -- but galvanic isolation fixed it for me, and it never disconnected once since I did that.

About GND and VDD: simply keep the USB +5V separate from the board VDD, and the USB GND separate from the board GND. No electrical connection between USB and the board at all.

Okay i understand. Here is my solution. Could this work? I will try to prototype this but first i need to buy some optos. But before i do that, i will clearly understand this