TTL Serial to Step/Dir module

[strostkovy]

I've found the reason I don't finish many machines is because of electronics, despite that being my specialty. So I've decided to build projects with more modules such as stepper drivers and off the shelf CNC controllers. However, many of the machines I would like to build are not practical to program with G code, and instead need custom interfaces for productive use. For a backgauge I want to type a number and have it slide to positions. For a press brake I want to have several programs I can create or recall involving back gauge dimensions, angles, and correction factors, without having to calculate ram positions manually. Further, some projects may be hybrid electric/pneumatic/hydraulic and need multiple sensors to decide the next move, rather than a simple sequence.

I can design and make a step/direction pulse generator every time I build something, but it would save so much time to just have a module that accepts SPI or I2C commands and handles the step/direction lines independently. Essentially, I want to pass G-code (or something similar) one line at a time to a motion controller.

I've found a few things that work, but they include drivers that I can't use, or need a computer connection, or only have manual entry, etc.

So is anyone aware of any such module I can use to handle motion control like this?

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[__Britt]

How about Grbl on an Arduino Mini? Interface is G-code streamed over the UART; outputs up to 30khz step & direction; as well as supporting limit switches, homing, and outputs for coolant pumps & spindles.

https://github.com/gnea/grbl

https://store.arduino.cc/usa/arduino-pro-mini

Note that even though the Pro Mini is listed as retired by Arduino.cc; it's still widely available from the usual sources (Amazon, eBay, BangGood, Sparkfun, Adafruit, etc). Alternatively, if you are making your own PCB; you can just drop an ATMega328 on it to be the pulse generator (note that you will need to provide a 16mhz crystal for the clock; the internal RC oscillator isn't really good enough).

If you would like a setup that has more UI functionality & expandability while remaining an integrated system; I have made a fork of the version of Grbl for the Arduino Mega and added a bunch of functionality to it; including support for common 3D printer character-based LCD control panels, jog wheels, and a keypad for controlling the machine and entering data. I am in the process of building an expansion interface for the software that will allow end-user created code modules to be easily integrated into the Grbl system; and still allow for easy upgrades of the base Grbl software (an early version of this can be found in the grbl_expansion_interface.h & grbl_expansion_interface.c files in my version of Grbl-mega).

My version can be found here:
https://github.com/bdurbrow/grbl-Mega/

[philba]

How about Grbl on an Arduino Mini? Interface is G-code streamed over the UART; outputs up to 30khz step & direction; as well as supporting limit switches, homing, and outputs for coolant pumps & spindles.

https://github.com/gnea/grbl

https://store.arduino.cc/usa/arduino-pro-mini

Note that even though the Pro Mini is listed as retired by Arduino.cc; it's still widely available from the usual sources (Amazon, eBay, BangGood, Sparkfun, Adafruit, etc). Alternatively, if you are making your own PCB; you can just drop an ATMega328 on it to be the pulse generator (note that you will need to provide a 16mhz crystal for the clock; the internal RC oscillator isn't really good enough).

If you would like a setup that has more UI functionality & expandability while remaining an integrated system; I have made a fork of the version of Grbl for the Arduino Mega and added a bunch of functionality to it; including support for common 3D printer character-based LCD control panels, jog wheels, and a keypad for controlling the machine and entering data. I am in the process of building an expansion interface for the software that will allow end-user created code modules to be easily integrated into the Grbl system; and still allow for easy upgrades of the base Grbl software (an early version of this can be found in the grbl_expansion_interface.h & grbl_expansion_interface.c files in my version of Grbl-mega).

My version can be found here:
https://github.com/bdurbrow/grbl-Mega/

Actually, I'd use a Nano, you can program it via USB and then use the TTL serial interface. GRBL works fine on it. Cheap and available everywhere. Screw terminal boards are available for it.

[__Britt]

Actually, I'd use a Nano,

Make sure it's a '328 based one - they have a (new?) one called the "Arduino Nano Every" that's based on a different chip (ATMega4809) that a quick look at the datasheet for doesn't look like it's directly compatible with the standard version of Grbl (I think the registers for the timers are different?).

If you connect to the D0 & D1 header pins for TTL serial on the Nano, be aware that there's a 1K resistor between the header pins and the FTDI USB interface chip; so your drive of that will have effectively a 1K pull up on it. Depending on what you are driving it with; you might want to replace that resistor with something of a higher value.

The Mini, of course, because it has no on-board USB interface, has no resistors.